OGC Geotech Interoperability Experiment Engineering
Report

Mickaël Beaufils, Katharina Schleidt, Hylke van Der Schaaf, Daniel Ponti,
Neil Chadwick, Derrick Dasenbrock

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Mickaël Beaufils, Katharina Schleidt, Hylke van Der Schaaf, Daniel Ponti, Neil Chadwick, et al. OGC Geotech Interoperability Experiment Engineering Report. Open Geospatial Consortium. 2024. [hal-05408483](https://HAL Id: hal-05408483)

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# OGC Geotech Interoperability Experiment Engineering Report

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## Warning

This document is not an OGC Standard. This document is an OGC Public Engineering Report created as a deliverable in an OGC Interoperability Initiative and is not an official position of the OGC membership. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an OGC Standard.

Further, any OGC Engineering Report should not be referenced as required or mandatory technology in procurements. However, the discussions in this document could very well lead to the definition of an OGC Standard.

Document type: OGC® Engineering Report

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Document stage: Approved

Document language: English
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# Table of Contents

1. Abstract 4

2. Introduction 5

2.1. Motivation 5

2.2. Participating standard communities 6

2.3. Supporting community 8

3. Geotechnical concepts 10

3.1. What is the conceptual model about? 10

3.2. Which standards and versions were considered in this conceptual model? 10

3.3. Origin of Books A, B, C concept 12

3.4. Definition 12

3.5. Book A Principles 13

3.6. Book B Principles 48

3.7. Book C Principles 80

4. OGC and ISO models 87

4.1. General mapping 87

4.2. General considerations 92

4.3. ISO 19148 and ISO 19156 99

4.4. SensorThings API data model 108

4.5. GeoSciML 111

4.6. GroundWaterML2 116

4.7. EPOS WP15 118

4.8. LandInfra and InfraGML 120

4.9. INSPIRE Theme III: Natural Risk Zone 122

5. Implementation guide, resources, and examples 124

5.1. About implementation 124

5.2. OGC APIs 124

5.3. Introduction to FROST 125

5.4. FROST Plugin for geotech 125

5.5. Exposing geotech investigation data with OGC SensorThings API 129

5.6. Semantics for geotech 191

6. Conclusions and future work 193

6.1. Plans for Future Work 193
# Chapter 1. Abstract

This Engineering Report (ER) describes the outcomes of the Open Geospatial Consortium (OGC) Geotech Interoperability Experiment (IE). The objective of this IE was to develop a common conceptual model for describing geotechnical engineering data that bridges existing specifications for encoding those data and which could be integrated across OGC and buildingSMART International Standards,

This ER is directly imported from the project wiki found here: https://github.com/opengeospatial/Geotech/wiki.
# Chapter 2. Introduction

## 2.1. Motivation

BIM, GIS & Digital Twins introduce or emphasize several requirements regarding the data. This mostly concern the built environment but also orientate the way the geoscience data are expected to be delivered.

### 2.1.1. Semantic coherence for Geotechnics and the necessity of models federation

The main concern is about semantics. As also identified as the main criteria of interoperability in the FAIR principles, data shall be described in a non-ambiguous way. Those definitions shall be shared by the community independently from the standard that is used. For that purpose, a federation of model is needed. Then OGC and bSI will derive logical models for OGC based and bSI based (IFC) standards.

> This effort would fit into the ongoing collaboration between OGC initiatives and bSI projects on georeferencing, infrastructures alignments, procedural geometries, voxels, etc...

> — Richard Petrie (bSI), Scott Simmons (OGC)

Although, this project is the opportunity to align with other standards. A non-exhaustive list of them include AGS/AGSi, DIGGS, Geo3DML, GeoValML, BoreholeML, ResqML, etc.

On the OGC side, this project is identified as the main contributor to leverage the OGC based standards. For the moment, the IFC schema extension for Geotechnics is mainly supported by the GeoSubgroup of the IFC Tunnel but it aims to serve all the IFC infrastructure projects.
<figure><img src="image_2.png" /><figcaption>Figure 1. Geotech Interoperability Experiment</figcaption></figure>

## 2.2. Participating standard communities

This GeotechIE project is operated thanks to the collaboration of people from multiple communities.

### 2.2.1. Open Geospatial Consortium

The Open Geospatial Consortium (OGC) is an international industry consortium participating in a consensus process to develop publicly available interface standards. The geoscience standards, especially GeoSciML have been designed jointly with CGI-IUGS, giving them the status of reference standards for geology. Efforts from OGC have also been made to extend those standards to address the topic of hydrogeology. The result was the standard GroundwaterML2 that is an extension of GeoSciML. The geoscience standards also rely on the ISO19156 standard that is a cross domain model for Observations, Measurements and Sampling.

Contributors from OGC include:

* Mickaël Beaufils, GeoScienceDWG Chairman, GeotechIE Leader, BRGM

* Scott Simmons, OGC Chief Standards Officer

* Kathi Schleidt, OMS SWG co-chair, DataCove

* Hylke van der Schaaf, SensorThingsAPI SWG co-chair, Fraunhofer IOSB
### 2.2.2. buildingSMART International

buildingSMART International (bSI) is an international organization committed to creating and developing open digital ways of working for the built asset industry. buildingSMART standards help asset owners and the entire supply chain work more efficiently and collaboratively through the entire project and asset lifecycle. The Industry Foundation Classes (IFC), ISO 16739, are the official standards for OpenBIM. Major evolutions have been made on them, especially with IFC v4.x, to extend their capacities: IFC 4.0 introduces the extension of IFC from building to infrastructure. IFC 4.3 is having another step forward in the direction of environmental modeling. It introduces the capacity of describing non-man-made objects and also georeferencing. Two major and necessary improvements to envisage the description of geotechnical objects or even earthworks. The IFC Common Schema is identified to offer a cross-infrastructure support to address those domains. Major evolutions in that direction are made through the IFC Tunnel project.

Contributors from bSI include:

* Jonas Weil, IFC Tunnel Geo-Subgroup Leader, IC Group

* Rie Wada, Oyo Company

### 2.2.3. AGS

AGS is the Association of Geotechnical and Geoenvironmental Specialists, a UK based trade association established to improve the profile and quality of geotechnical and geoenvironmental engineering. In 1991, the AGS set up a method for transferring data between industry organizations. This is known to many simply as ‘AGS format’ or ‘AGS data format’ and provides a standard way to transfer ground investigation, laboratory testing and monitoring data between the contributing parties of a project which involves geotechnical or geoenvironmental elements. The AGS format has been improved and enhanced over the years and is now widely used in the UK. It has also been adopted and adapted for use in Hong Kong, Singapore, Australia, New Zealand and parts of the Middle East. More recently, AGS has developed and released AGSi, a new data format for the exchange of ground model and interpreted data in the ground domain. Work is also being carried out on a new format for piling data.

Contributors from AGS include:

* Neil Chadwick, AGS Data Management Working Group

* Tony Daly, AGS Data Management Working Group

### 2.2.4. DIGGS

DIGGS (Data Interchange for Geotechnical and Geoenvironmental Specialists) is a special project of the Geo-Institute of the American Society of Civil Engineers, and the interchange standard has been adopted as the “Provisional Standard Practice for Digital Interchange of Geotechnical Data” by AASHTO, the association that represents highway and transportation departments across the USA and serves as a liaison between State departments of transportation and the Federal government. DIGGS builds off of the AGS data dictionary for exploratory data, and utilizes existing technologies and standards (eg. XML, GML, WITSML, OMS) in its schema design. Although initially focused on exploratory data collected in US practice, DIGGS supports 1D, 2D, and 3D sampling geometries, any
language, and can reference any codes or language conventions, and thus is designed to be
extensible and compatible with non-US practice. Beyond exploratory data obtained from boreholes,
trenches and outcrops, DIGGS is being extended to exchange field survey geophysical data,
construction data from grouting and pile load testing activities, performance monitoring
instrumentation, and geo-environmental site monitoring.

Contributors from DIGGS include:

* Dan Ponti, DIGGS Steering Committee

* Derrick Dasenbrock

**2.3. Supporting community**

**2.3.1. ISSMGE TC222**

The International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) is the pre-
eminent professional body representing the interests and activities of Engineers, Academics and
Contractors all over the world that actively participate in geotechnical engineering. The aim of the
International Society is the promotion of international co-operation amongst engineers and
scientists for the advancement and dissemination of knowledge in the field of Geotechnics, and its
engineering and environmental applications.

Contributors from ISSMGE TC222 include:

* Magnus Romoen, ISSMGE TC222 Chairman, NGI

* Mats Kalstrom, NGI

**2.3.2. ITA WG22**

The International Tunnelling and Underground Space Association (ITA) aims to encourage the use of the subsurface for the benefit of public, environment and sustainable development and to promote advances in planning, design, construction, maintenance and safety of tunnels and underground space, by bringing together information thereon and by studying questions related thereto.

WG22 is the Working Group dedicated to information modeling in tunelling.

Contributors from ITA WG22 include:

* Florent Robert, ITA WG22 Animator, CETU

**2.3.3. CGI-IUGS**

The Commission for the Management and Application of Geoscience Information (CGI) is a working
subcommittee of the International Union of Geological Sciences. Its mission is to enable the global
exchange of knowledge about geoscience information and systems. CGI is the governing body
responsible for the XML-based exchange languages Geoscience Markup Language (GeoSciML - in
collaboration with the Open Geospatial Consortium) and EarthResource Markup Language
(EarthResourceML). The CGI and its members also play a significant role in the OneGeology initiative.

Contributors from ITA WG22 include:

* Harvey Thorleifson, CGI-IUGS Chairman

* Edd Lewis, BGS

### 2.3.4. EGS UGEG

The Urban Geology Expert Group (UGEG) from EuroGeoSurvey (EGS) delivers high quality scientific information and expertise to the EU's urban decision-makers and European Institutions in the areas of sustainable urban development, urban resilience, future climate proofing of cities, SMART cities and safe construction.

Contributors from EGS UGEG include:

* Philip Wehrens, SwissTopo

* Teemu Lindqvist, GTK

### 2.3.5. MINnD

The MINnD National Project in France is since its creation in 2014 is the French initiative to push openBIM extensions for infrastructure description. Majors contributions from MINnD have been brought to the development of IFC Bridge, IFC Road, IFC Rail. IFC Tunnel is largely influenced by the work made by the MINnD Tunnel (WG1-4) and MINnD Geotechnics (WG1-5) projects, that are themselves part of the wider MINnD Underground Infrastructure. MINnD Geotechnics emphasized the importance of building on and connecting existing standards.

Contributors from MINnD include:

* Isabelle Halfon, BRGM

* Sylvie Bretelle, ANTEA

* Elodie Vautherin, Fondasol

* Pierre Garnier, WSP

* Alexis Serieys, SETEC Terrasol

* François Robida, MINnD
# Chapter 3. Geotechnical concepts

## 3.1. What is the conceptual model about?

A conceptual schema or conceptual data model is a map of concepts and their relationships. This describes the semantics of a domain and represents a series of assertions about its nature. Specifically, it describes the things of significance to a domain (entity classes), about which it is inclined to collect information, and its characteristics (attributes) and the associations between pairs of those things of significance (relationships). This model's perspective is independent of any underlying data format or application.

The Conceptual Model proposes: * Definition and properties for relevant concepts identified by the geotechnical community, and * Mapping with existing standards

## 3.2. Which standards and versions were considered in this conceptual model?

### 3.2.1. ISO 19148

Linear Referencing Systems enable the specification of positions along linear objects. The approach is based upon the Generalized Model for Linear Referencing[12] first standardized within ISO 19133:2005. This document extends that which was included in ISO 19133, both in functionality and explanation.

ISO 19109 supports features representing discrete objects with attributes with values which apply to the entire feature. ISO 19123 allows the attribute value to vary, depending upon the location within a feature, but does not support the assignment of attribute values to a single point or length along a linear feature. Linearly located events provide the mechanism for specifying attribution of linear objects when the attribute value varies along the length of a linear feature. A Linear Referencing System is used to specify where along the linear object each attribute value applies. The same mechanism can be used to specify where along a linear object another object is located, such as guardrail or a traffic accident.

It is common practice to segment a linear object with linearly located events, based upon one or more of its attributes. The resultant linear segments are attributed with just the attributes used in the segmentation process, ensuring that the linear segments are homogeneous in value for these segmenting attributes.

### 3.2.2. OGC Observations, Measurements, and Samples / ISO 19156

This standard specifies an XML implementation for the OGC and ISO Observations and Measurements (O&M) conceptual model (OGC Observations and Measurements v2.0) also published as ISO 19156, as well as OGC Abstract Specification Topic 20: Observations, Measurements, and Samples, including a schema for Sampling Features. This encoding is an essential dependency for the OGC Sensor Observation Service (SOS) Interface Standard. More specifically, this standard defines XML schemas for observations, and for features involved in sampling when making
observations. These provide document models for the exchange of information describing
observation acts and their results, both within and between different scientific and technical
communities.

More details here: https://www.ogc.org/standards/om

3.2.3. OGC GeoSciML 4.1

GeoSciML is a model of geological features commonly described and portrayed in geological maps, cross sections, geological reports, and databases. The model was developed by the IUGS CGI (Commission for the Management and Application of Geoscience Information) and version 4.1 is the first version officially submitted as an OGC standard. This specification describes a logical model and GML/XML encoding rules for the exchange of geological map data, geological time scales, boreholes, and metadata for laboratory analyses. It includes a Lite model, used for simple map-based applications; a basic model, aligned on INSPIRE, for basic data exchange; and an extended model to address more complex scenarios.

The specification also provides patterns, profiles (most notably of Observations and Measurements - ISO19156), and best practices to deal with common geoscience use cases.

More details here: http://geosciml.org/

3.2.4. OGC GroundWaterML 2.2

This standard describes a conceptual and logical model for the exchange of groundwater data, as
well as a GML/XML encoding with examples.

More details here: https://www.ogc.org/standards/gwml2

3.2.5. OGC LandInfra

The scope of the Land and Infrastructure Conceptual Model is land and civil engineering
infrastructure facilities. Anticipated subject areas include facilities, projects, alignment, road,
railway, survey, land features, land division, and "wet" infrastructure (storm drainage, wastewater,
and water distribution systems). The initial release of this standard is targeted to support all of
these except wet infrastructure.

More details here: https://www.ogc.org/standard/infragml/

3.2.6. bSI IFC Tunnel proposal

IFC is a standardized, digital description of the built asset industry. IFC4.3 is an open, international standard (ISO 16739-1:2018) and promotes vendor-neutral, or agnostic, and usable capabilities across a wide range of hardware devices, software platforms, and interfaces for many different use cases. More about IFC, its uses and adoption may be found here.

While geotechnics was first addressed in IFC4.3, major changes are discussed in the context of the
IFC Tunnel project. The mapping that is described in those pages is based on this discussed proposal
and do not apply to IFC4.3.
### 3.2.7. AGS 4.1

AGS is a text file format used to transfer data reliably, between organizations in the site investigation industry, independent of software, hardware or operating system.

In 1991, the AGS set up a method for transferring data between industry organizations. This is known to many simply as 'AGS Format' or 'AGS Data Format' and provides a standard way to transfer ground investigation, laboratory testing and monitoring data between the contributing parties of a project which involves geotechnical or geoenvironmental elements.

More details here: https://www.ags.org.uk/data-format/ags4-data-format/ags-4-1/

### 3.2.8. DIGGS 2.5.a

DIGGS is an XML-based standard for the transfer of geotechnical data. This current version is limited to ground exploration data derived from boreholes, soundings, trenches and outcrops, including in-situ testing and monitoring, and laboratory test data. It is built from the AGS data dictionary, extending it for US practice, and leverages GML and WITSML XML standards for describing spatial and geometric and unit of measurement symbology, respectively.

More details here: https://www.geoinstitute.org/special-projects/diggs/schema-tools

## 3.3. Origin of Books A, B, C concept

In order to separate the factual data from the investigation phases, the analysis/interpretation documents and the design documents, the AFTES (French Tunnelling and Underground Space Association), initially instituted in the recommendation GT32R1F1 of 2004 (then in the recommendation GT32R3F1 of 2016 which abrogates GT32R1F1), the structuring of the Tendering Documents, around three successive sub-folders or "books," using the results of the previous book to define the characteristics of the next book.

## 3.4. Definition

### 3.4.1. Book A: Factual data

Factual Data Collection: This is a non-binding compilation of project-specific data and results. It is further divided into three sub-books:

* A1: Geotechnical input data;

* A2: Input data for neighbouring buildings; and

* A3: Input data natural and human environment.

### 3.4.2. Book B: Models and their components

Geotechnical report: this contractual document gives the interpretation of the project manager on the whole of the data of the book A. It is also sub-divided into three sub-books:

* B1: Geotechnical synthesis memorandum;
* B2: Sensitivity memorandum for neighboring constructions; and

* B3: Comments on environmental constraints.

Each book B1, B2 and B3 ends with a register of uncertainties.

### 3.4.3. Book C: Design report

Design brief: this explanatory and non-contractual document produced by the project manager explains and justifies the design of the civil engineering works, the execution methods and the sizing of the works.

## 3.5. Book A Principles

The main idea of the Book A phase is to collect factual data and express their content. In Book A, one will find all the documents produced in the past on the studied area (geological maps, collection of geologists, etc.). Generally, it is necessary to complete these elements with specific investigations.

### 3.5.1. Acts

Geotechnical engineers and team can perform several acts in order to better understand the environment:

* Observation

* Observing Procedure

* Observable Properties

* Sampling and Preparation

### 3.5.2. Proxies

Observation, measurement, and sampling activities are applied on features of interest that act as proxies.

These include:

* Borehole; and

* Trial Pit

Some proxies can be collected on the field, to be studied elsewhere (e.g., in a laboratory), they are called:

* MaterialSample

Note: A borehole core is considered as a Material Sample.
### 3.5.3. FAQ

#### What do observations and measurements include?

All kind of observation and measurements that can be performed.

This include:

* Geological observations,

* Geotech in-situ tests,

* Geotech laboratory tests,

* Environmental analysis, and

* Geophysics.

#### Why focusing on acts and not just providing results?

The proposed conceptual model follows the principles of the OGC Standard for Observations, Measurements, and Samples.

In geotechnics and in many other domains results must be contextualized and can only be used in a specific context.

Acts of observation, measurement or sampling provide this context and the necessary metadata to enable the use and reuse of the data.

### 3.5.4. Borehole

A Borehole is the generalized term for any narrow shaft drilled in the ground, either vertically, horizontally, inclined, or deviated.

#### Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GeoSciML</td><td>Borehole</td><td>A Borehole is the generalized term for any narrow shaft drilled in the ground, either vertically, horizontally, or inclined.</td></tr><tr><td>IFC</td><td>IFCBorehole</td><td>A Borehole is the generalized term for any narrow shaft drilled in the ground, either vertically, horizontally, or inclined.</td></tr><tr><td>AGS</td><td>LOCA</td><td>AGS LOCA includes exploratory holes of any type, e.g., borehole, trial pits, CPT</td></tr></tbody></table>
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>DIGGS</td><td>Borehole</td><td>A sampling feature feature that is a deep, narrow excavation made by drilling and/or extraction of earth material. Boreholes are constructed typically for the purpose of investigating subsurface geologic or geotechnical conditions, exploring for water or oil, for installation of wells or other downhole monitoring installations.</td></tr><tr><td>DIGGS</td><td>Sounding</td><td>A sampling feature that is created by a measurement or construction activity through insertion of a probe or tool into the ground.</td></tr></tbody></table>

## Properties

A proposed list of borehole properties is as follows.

<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>id</td><td>Identifier</td></tr><tr><td>name</td><td>A human-readable display name for the borehole.</td></tr><tr><td>description</td><td>A human-readable description for the borehole.</td></tr><tr><td>metadata</td><td>A URI referring to a metadata record describing the provenance of data.</td></tr><tr><td>remarks</td><td>Any general remarks about the borehole.</td></tr><tr><td>boreholePurpose</td><td>The purpose for which the borehole was drilled.</td></tr><tr><td>boreholeUse</td><td>The current use of the borehole which could differ from the purpose for which the borehole was initially drilled.</td></tr><tr><td>status</td><td>The current status of the borehole. (eg. planned, completed, destroyed)</td></tr><tr><td>source</td><td>Details and citations to source materials for the borehole and, if available, providing URLs to reference material and publications describing the borehole. This could be a short text synopsis of key information that would also be in the metadata record referenced by metadata_uri.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>associatedFile</td><td>Identifies external files associated with this borehole. This allows for the feature to be further elaborated with information that cannot be represented by ASCII text, such as a photograph or other media, binary data, or a formatted report.</td></tr><tr><td>whenDestroyed</td><td>The time period during which the hole was destroyed or forever abandoned. This date must occur after all related observations, measurements or activities had been performed in the borehole, and should reflect the time after which no observations or activities are possible in the hole.</td></tr><tr><td>drillingMethod</td><td>The method(s) used to construct the hole.</td></tr><tr><td>drillingEquipment</td><td>The equipment used to construct the hole.</td></tr><tr><td>operator</td><td>The organization or agency responsible for commissioning of the borehole (as opposed to the agency which drilled the borehole).</td></tr><tr><td>driller</td><td>The organization responsible for drilling the borehole (as opposed to commissioning the borehole).</td></tr><tr><td>drillStartDate</td><td>The datetime of the start of drilling formatted according to ISO8601 (e.g., 2012-03-17T00:00:00).</td></tr><tr><td>drill</td><td>The date of the end of drilling formatted according to ISO8601 (e.g., 2012-03-28T00:00:00).</td></tr><tr><td>BoreholeLengthPlanned</td><td>The planned length of a borehole e.g., in a site investigation program.</td></tr><tr><td>BoreholeLengthDrilled</td><td>The total length of a borehole as drilled and logged. Length may have different sources (e.g., driller's measurement, logger's measurement, survey measurement).</td></tr><tr><td>startPoint</td><td>The position relative to the ground surface that marks the origin for measuring distance along a borehole's trajectory.</td></tr><tr><td>collarGeometry</td><td>2D or 3D point geometry that represents the location of the borehole at the ground surface in geographic space.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>srsName</td><td>The URI of a spatial reference system. If collarGeometry is a 2D point, this is the horizontal SRS. If collarGeometry is a 3D point, this must be a either a 3D SRS, a known compound SRS, or the EPSG code of the horizontal component of a compound SRS.</td></tr><tr><td>elevation_srsName</td><td>The URI of a spatial reference system of the elevation of the collarGeometry. (e.g., mean sea level). Mandatory if collarGeometry and srsName is the EPSG code of the horizontal component of a compound SRS. elevation_srsName shall be a one dimensional vertical SRS (i.e., EPSG code in the range 5600-5799).</td></tr><tr><td>positionalAccuracy</td><td>An estimate of the accuracy of the location of the collarGeometry. Ideally, this would be a quantitative estimate of accuracy (e.g., 20 metres).</td></tr><tr><td>locality</td><td>Non-coordinate location information for a borehole.</td></tr><tr><td>localCoordinates</td><td>A geometry object that holds the values of local coordinates for the borehole collar location. This object is used to carry information about the location of a feature in its original local reference system if not originally recorded in a well-known SRS.</td></tr><tr><td>azimuth</td><td>For a straight but inclined borehole, the azimuth of the borehole's trajectory as a plane angle measurement, where 0 is true north, incrementing clockwise.</td></tr><tr><td>inclination</td><td>For a straight but inclined borehole, the inclination of the borehole's trajectory as a plane angle measurement, where 0 is vertical and 90 is horizontal.</td></tr><tr><td>trajectoryType</td><td>Describes the general character of the borehole's trajectory. (vertical, inclined, deviated)</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>trajectoryGeometry</td><td>A geometry that represents and locates the borehole shape. It is represented as a lineString in 3D space and is of the same SRS as collarGeometry. A borehole can have multiple centerlines to represent sidetracks or to serve as a linear referencing element for observations within the borehole that may be located relative to different datums (eg. ground surface vs rig table).</td></tr><tr><td>linearReferencing</td><td>Defines the linear spatial reference system for the borehole. This LSRS can then be used to define the location of observations within the borehole as a 1D position along the borehole's trajectory, rather than in geographic coordinates.</td></tr><tr><td>boreholeType</td><td>Type of borehole. (core drilling, destructive drilling, trial pit, sounding)</td></tr></tbody></table>

## FAQ

### What about Borehole core?

A borehole core is considered as a MaterialSample.

See MaterialSample for its description.

### What about Borehole Logs and Observations?

All observations, measurements and test descriptions from a Borehole are considered as Observations.

See Observation for their description.

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/10

### 3.5.5. Trial Pit

A relatively shallow excavation into the earth's surface, dug either manually or by a mechanical excavator. Samples, observations and tests in the trial pit are referenced in a linear referencing system only (1D). This is a legacy sampling feature to support AGS trial pit constructs.

### Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GeoSciML</td><td>TrialPit (candidate)</td><td>Same as DIGGS.</td></tr></tbody></table>
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>IFC</td><td>Borehole</td><td></td></tr><tr><td>AGS</td><td>LOCA</td><td>AGS LOCA includes exploratory holes of any type, e.g., borehole, trial pit, CPT</td></tr><tr><td>DIGGS</td><td>TrialPit</td><td>A relatively shallow excavation into the earth's surface, dug either manually or by a mechanical excavator. Samples, observations and tests in the trial pit are referenced in a linear referencing system only (1D). This is a legacy sampling feature to support AGS trial pit constructs. The TrenchWall sampling feature should be used to represent more detail on walls of pits or trenches in 2D.</td></tr></tbody></table>

## Properties

A proposed list of trial pit properties follows.

<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>id</td><td>Identifier</td></tr><tr><td>name</td><td>A human-readable display name for the trial pit.</td></tr><tr><td>description</td><td>A human-readable description for the trial pit.</td></tr><tr><td>metadata</td><td>A URI referring to a metadata record describing the provenance of data.</td></tr><tr><td>remarks</td><td>Any general remarks about the trial pit</td></tr><tr><td>pitPurpose</td><td>The purpose for which the trial pit was created.</td></tr><tr><td>pitUse</td><td>The current use of the trial pit which could differ from the purpose for which the trial pit was initially created.</td></tr><tr><td>status</td><td>The current status of the trial pit (e.g., planned, completed, destroyed).</td></tr><tr><td>source</td><td>Details and citations to source materials for the trial pit and, if available, providing URLs to reference material and publications describing the trial pit. This could be a short text synopsis of key information that would also be in the metadata record referenced by metadata_uri.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>associatedFile</td><td>Identifies external files associated with this trial pit. This allows for the feature to be further elaborated with information that cannot be represented by ASCII text, such as a photograph or other media, binary data, or a formatted report.</td></tr><tr><td>whenDestroyed</td><td>The time period during which the trial pit was destroyed or forever abandoned. This date must occur after all related observations, measurements or activities had been performed in the trial pit, and should reflect the time after which no observations or activities are possible.</td></tr><tr><td>constructionMethod</td><td>The method(s) used for this trial pit (manual, mechanical)</td></tr><tr><td>constructionEquipment</td><td>The equipment used to construct the trial pit</td></tr><tr><td>operator</td><td>The organization or agency responsible for commissioning of the trial pit (as opposed to the agency which drilled the trial pit).</td></tr><tr><td>excavator</td><td>The organization responsible for digging the trial pit (as opposed to commissioning the trial pit).</td></tr><tr><td>pitStartDate</td><td>The datetime of the start of excavation formatted according to ISO8601 (e.g., 2012-03-17T00:00:00).</td></tr><tr><td>pit</td><td>The date of the end of excavation formatted according to ISO8601 (e.g., 2012-03-28T00:00:00).</td></tr><tr><td>pitDepthPlanned</td><td>The planned depth of a trial pit e.g., in a site investigation program.</td></tr><tr><td>pitDepthConstructed</td><td>The total depth of a trial pit as constructed and logged.</td></tr><tr><td>pitLength</td><td>The length of the long horizontal dimension of the pit.</td></tr><tr><td>pitWidth</td><td>The length of the short horizontal dimension of the pit.</td></tr><tr><td>startPoint</td><td>The position relative to the ground surface that marks the origin for measuring distance along a trial pit's trajectory</td></tr><tr><td>pitShoring</td><td>Description of shoring equipment and method.</td></tr><tr><td>pitBackfill</td><td>Information on construction of the trial pit backfill.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition</td></tr></thead><tbody><tr><td>locationGeometry</td><td>2D or 3D point geometry that represents the location of the trial pit at the ground surface in geographic space.</td></tr><tr><td>srsName</td><td>The URI of a spatial reference system. If collarGeometry is a 2D point, this is the horizontal SRS. If collarGeometry is a 3D point, this must be either a 3D SRS, a known compound SRS, or the EPSG code of the horizontal component of a compound SRS.</td></tr><tr><td>elevation_srsName</td><td>The URI of a spatial reference system of the elevation of the collarGeometry. (e.g., mean sea level). Mandatory if collarGeometry and srsName is the EPSG code of the horizontal component of a compound SRS. elevation_srsName shall be a one dimensional vertical SRS (i.e., EPSG code in the range 5600-5799).</td></tr><tr><td>positionalAccuracy</td><td>An estimate of the accuracy of the location of the collarGeometry. Ideally, this would be a quantitative estimate of accuracy (e.g., 20 metres).</td></tr><tr><td>locality</td><td>Non-coordinate location information for a trial pit.</td></tr><tr><td>localCoordinates</td><td>A geometry object that holds the values of local coordinates for the trial pit location. This object is used to carry information about the location of a feature in its original local reference system if not originally recorded in a well-known SRS</td></tr><tr><td>trajectoryGeometry</td><td>A geometry lineString in 3D space that represents the top and base of the trial pit. This object is of the same SRS as locationGeometry.</td></tr><tr><td>linearReferencing</td><td>Defines the linear spatial reference system for the trial pit. This LSRS can then be used to define the locations of observations within the trial pit as a 1D position along the trial pit's trajectory, rather than in geographic coordinates.</td></tr></tbody></table>

## FAQ

**How are observed properties that vary laterally in a trial pit handled in 1D?**

Observations of the same property where results vary laterally in the pit at the same depth are assigned different stratum codes. A stratum code is a letter or number code that links the stratum shown on a face sketch of the trial pit to the observation. In OMS, this would be accomplished by
having different features of interest identified for the same 1D location.

See Github issue: https://github.com/opengeospatial/Geotech/issues/18

### 3.5.6. Observation

An observation is an act associated with a discrete time instant or period through which a number, term or other symbol is assigned to a characteristic. This act involves application of a specified procedure, such as a sensor, instrument, algorithm or process chain. The procedure may be applied in-situ, remotely, or ex-situ with respect to the sampling location. The result of an observation is an estimate of the value of a property of some feature; an observation is a property-value-provider for a feature-of-interest. Use of a common model allows observation data using different procedures to be combined unambiguously.

In conventional measurement theory the term “measurement” is used. However, a distinction between measurement and category-observation has been adopted in more recent work so the term “observation” is used here for the general concept. “Measurement” may be reserved for cases where the result is a numerical quantity.

The observation itself is also a feature, since it has properties and identity. Observation details are important for data discovery and for data quality estimation. The observation could be considered to carry “property-level” instance metadata, which complements the dataset-level and feature-level metadata commonly provided via catalogue services (e.g., ISO 19115 or other community agreed one).

#### Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC OMS</td><td>Observation</td><td>An observation is an act associated with a discrete time instant or period through which a number, term or other symbol is assigned to a characteristic. This act involves application of a specified procedure, such as a sensor, instrument, algorithm or process chain. The procedure may be applied in-situ, remotely, or ex-situ with respect to the sampling location. The result of an observation is an estimate of the value of a property of some feature; an observation is a property-value-provider for a feature-of-interest. Use of a common model allows observation data using different procedures to be combined unambiguously.</td></tr><tr><td>IFC</td><td>GeoscienceObservation</td><td>Detailed collected information, including measured parameters, descriptions etc. related to geoscientific observations that can be assigned to physical or spatial elements using IfcRelAssignsToProduct.</td></tr><tr><td>AGS</td><td></td><td>No specific concept as such as all data is treated similarly in AGS data, whether it be location data, hole/test/other metadata or results (i.e. observations in this context)</td></tr><tr><td>DIGGS</td><td>Observation</td><td>An interval or region defined at a sampling feature that contains qualitative observations or interpretations.</td></tr></tbody></table>
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>DIGGS</td><td>Measurement</td><td>An act or event whose results are quantitative estimates of the values of properties of the target of an investigation. DIGGS currently has three specialized measurement objects, 1) a Test, which is a measurement made over a spatial domain, such as laboratory tests on samples collected in the field, or in-situ tests where measurements are made directly on site, 2) monitoring activities, which are measurements made over a temporal domain, such as water level measurements or inclinometer readings, and 3) a Material Test, which is for measurements made on material samples that are manufactured such that the result pertains only to the sample and not to any associated location.</td></tr></tbody></table>

# FAQ

## Observations and / or measurements?

Several distinctions can be made between Observations and Measurements. A common one being that Observations provide qualitative results whereas Measurements provide quantitative results.

The proposed conceptual model does not make this distinction. Yet soft typing can be applied if this distinction is considered necessary.

The DIGGS standard proposes an explicit distinction between Observations and Measurements.

## How to deal with multiple Observations / measurements?

It is very common for a procedures or test (especially for measurements) to provide a result composed of multiple values. This includes time series, z-series.

The proposed conceptual model offers a fine granularity which aims at being able to get any value separately. Each single observation or measurement (e.g., at a specific time of a timeseries and/or at a specific location of a z-series) is then contextualized and associated to its procedure and other metadata.
I don't want to retrieve single observations / measurements but have them grouped

Grouping of observations and measurements having some similarities is a basic function that
Observation APIs shall be able to manage.

Common grouping criteria include: ObservingProcedure, ObservedProperty, Time, Location and/or
FeatureOfInterest.

OGC APIs like SensorThingAPI offer such capacity.

GitHub issue

https://github.com/opengeospatial/Geotech/issues/19

3.5.7. Observing Procedure

Description of steps performed in order to determine the value of an observableProperty by an
Observer.

A typology of ObservingProcedure

* In-situ and remote observing procedure: the observation is made on the field, either directly or remotely.

* Ex-situ observing procedure: a sample is collected on the field and studied in a different place, generally a laboratory.

Realizations

<table>
   <thead>
    <tr>
     <td>
      Source
     </td>
     <td>
      Type
     </td>
     <td>
      Link
     </td>
     <td>
      Definition
     </td>
    </tr>
   </thead>
   <tbody>
    <tr>
     <td>
      BRGM
     </td>
     <td>
      Registry
     </td>
     <td>
      https://data.geoscience.f r/ncl/Proc
     </td>
     <td>
      This register lists the different methods and processes that can be used to acquire knowledge.
     </td>
    </tr>
    <tr>
     <td>
      DIGGS
     </td>
     <td>
      XML Schema
     </td>
     <td>
      https://www.diggsml.or g/schemas/2.5.a/ Geotechnical.xsd
     </td>
     <td>
      This schema document contains the currently adopted test procedure methods (objects), their properties and property definitions. In instance documents, these objects are contained within a parent Test or MaterialTest measurement object
     </td>
    </tr>
   </tbody>
  </table>

A non-exhaustive list of ObservingProcedure for geotechnics includes the following.
* Particle size distribution'@en|'Analyse granulométrique'@fr

* Cone penetration test'@en|'Essai de pénétration statique au cône'@fr

* Mechanical cone penetration test'@en|'Essai de pénétration statique pointe mécanique'@fr

* Electrical cone penetration test'@en|'Essai de pénétration au cône électrique'@fr

* piezocone penetration test'@en|'Essai de pénétration au piézocone'@fr

* Dynamic penetration test'@en|'Essai de pénétration dynamique'@fr

* Standard Penetration test'@en|'Essai de pénétration dynamique standard (SPT)'@fr

* Dynamic probing'@en|'Essai de pénétromètre dynamique'@fr

* Ménard pressuremeter test'@en|'Essai au pressiomètre Ménard'@fr

* Self-boring pressuremeter test'@en|'Essai pressiométrique autoforé'@fr

* Full displacement pressuremeter test'@en|'Essai au pressiomètre refoulant'@fr

* Dilatometer test'@en|'Essai au dilatomètre'@fr

* Flexible dilatometer test'@en|'Essai au dilatomètre flexible'@fr

* Borehole jack test'@en|'Essai au dilatomètre rigide diamétral'@fr

* Field vane test'@en|'Scissomètre de chantier'@fr

* Flat jack test'@en|'Mesure des contraintes au vérin plat'@fr

* Hydraulic Testing of pre-existing fractures (HTPF)'@en|'Mesure de contrainte par fracturation hydraulique (Essai HTPF)'@fr

* Water permeability test in a borehole using open systems'@en|'Essai de perméabilité à l'eau dans un forage ouvert (essai Lefranc)'@fr

* Water pressure test in rock (Lugeon packer test)'@en|'Essai de pression d'eau dans les roches (essai Lugeon)'@fr

* Pumping test'@en|'Essai de pompage'@fr

* Infiltrometer test'@en|'Essai d'infiltration'@fr

* Water permeability test in a borehole using closed systems'@en|'Essai de perméabilité à l'eau dans un forage en tube fermé'@fr

* Water content measure'@en|'Mesure de la teneur en eau pondérale'@fr

* Bulk density'@en|'Determination de la masse volumique du sol'@fr

* Particle density'@en|'Détermination de la masse volumique de particules solides'@fr

* Incremental loading oedometer test'@en|'Essai de compressibilité à l'oedométre par paliers'@fr

* Unconfined compression test'@en|'Essai de compression uniaxiale'@fr

* Unconsolidated undrained triaxial test'@en|'Essai triaxial non consolidé non drainé'@fr

* Consolidated undrained triaxial compression test on water saturated soils'@en|'Essai triaxial consolidé non drainé'@fr

* Consolidated drained triaxial compression test on water saturated soils'@en|'Essai triaxial consolidé drainé'@fr
* Direct shear test’@en|‘Essai de cisaillement direct’@fr

* Atterberg limits : liquid ans plastic limits’@en|‘Détermination des Limites d’Atterberg’@fr

* Shrinkage test’@en|‘Essai de dessiccation’@fr

* Measuring of the methylene blue adsorption capacity of a rocky soil — Determination of the methylene blue of a soil by means of the stain test’@en|‘Mesure de la capacité d’adsorption de bleu de méthylène d’un sol ou d’un matériau rocheux Détermination de la valeur de bleu de méthylène d’un sol ou d’un matériau rocheux par l’essai à la tache’@fr

* Determination of the organic matter content - Ignition method’@en|‘Détermination de la teneur pondérale en matières organiques d’un matériau méthode par calcination’@fr

* Determination of the organic matter content - Soil chemical test’@en|‘Détermination de la teneur pondérale en matières organiques d’un sol - méthode chimique’@fr

* Determination of the decomposition state (humification) of organic soils - Von Post test’@en|‘Détermination de l’état de décomposition (humification) des sols organiques - Essai Von Post’@fr

* Determination of the carbonate content - Calcimeter method’@en|‘Détermination de la teneur en carbonate - Méthode du calcimètre’@fr

* Determination of minimal and maximal density of cohesionless soils’@en|‘Détermination des masses volumiques minimale et maximale des sols non cohérents’@fr

* Laboratory vane test’@en|‘Essai scissométrique en laboratoire’@fr

* Oedometer swelling test - Swelling determination by testing on several specimens’@en|‘Essai de gonflement à l'oedomètre - Détermination des déformations par chargement de plusieurs éprouvette.’@fr

* Huder-Amberg swelling test’@en|‘Essai de gonflement Huder-Amberg’@fr

* Soil quality - Determination of water-soluble and acid-soluble sulfate’@en|‘Qualité du sol - Dosage du sulfate soluble dans l'eau et dans l'acide’@fr

* Determination of the compaction reference values of a soil type — Standard Proctor Test — Modified Proctor Test’@en|‘Détermination des références de compactage d’un matériau - Essai Proctor Normal - Essai Proctor modifié’@fr

* Indice CBR après immersion. Indice CBR immédiat. Indice Portant Immédiat - Mesure sur échantillon compacté dans le moule CBR.’@fr

* Rock - Determination of water content of rock - Oven-drying method’@en|‘Roches - Détermination de la teneur en eau pondérale - Méthode par étuvage’@fr

* Rock - Tests for physical properties of rock - Determination of density - Cutting curb - Water immersion methods’@en|‘Roches - Essais pour déterminer les propriétés physiques des roches - Détermination de la masse volumique - Méthodes géométriques et par immersion dans l'eau’@fr

* Rock - Tests for physical properties of rock - Determination of porosity’@en|‘Roches - Essais pour déterminer les propriétés physiques des roches - Détermination de la porosité’@fr

* Rock - Determination of the ultrasonic waves velocity in laboratory - Transmission method’@en|''Vitesse de propagation des ondes ultrasonores
• méthode par transparence'@fr

* Rock - Determination of the uniaxial compression strength'@en|''Roches

◦ Détermination de la résistance à la compression uniaxiale’@fr

* Rock - Determination of the tensile strength - Indirect method - Brazil test’@en|''Roches - Détermination de la résistance à la traction

◦ Méthode indirecte - Essai brésilien’@fr

* Rock - Determination of the triaxial compressive strength’@en|''Roches

◦ Détermination de la résistance à la compression triaxiale’@fr

* Rock - Direct shear testing along a rock joint - Normal surface joint, constant load testing’@en|‘Roches - Cisaillement direct selon une discontinuité de roche - Essai sous un effort constant, normal à la surface de discontinuité’@fr

* Rock - Determination of the Young modulus and the Poisson ratio’@en|‘Roches - Détermination du module de Young et du coefficient de Poisson’@fr

* Rock - Point load strength test - Franklin test’@en|‘Roches - Résistance sous charge ponctuelle - Essai Franklin’@fr

* Rock - Determination of the drill penetration index’@en|‘Roches - Détermination de l'indice de résistance à la pénétration par un foret’@fr

* Rock - Determination of the rock abrasiveness - Part 1 : Scratching-test with a pointed tool’@en|‘Roches - Détermination du pouvoir abrasif d'une roche - Partie 1 : essai de rayure avec une pointe’@fr

* Rock - Determination of the rock abrasiveness - Part 2 : Test with a rotating tool’@en|‘Roches - Détermination du pouvoir abrasif d'une roche - Partie 2 : essai avec un outil en rotation’@fr

* Tests for mechanical and physical properties of aggregates — Part 2: Methods for the determination of resistance to fragmentation’@en|‘Essais pour déterminer les caractéristiques mécaniques et physiques des granulats — Partie 2 : Méthodes pour la détermination de la résistance à la fragmentation’@fr

* Tests for mechanical and physical properties of aggregates — Part 1: Determination of the resistance to wear (micro-Deval)‘@en|‘Essais pour déterminer les caractéristiques mécaniques et physiques des granulats - Partie 1 : détermination de la résistance à l'usure (micro-Deval)’@fr

• Expert estimates or Engineering judgment’@en|‘Dire d’expert ou jugement de l’ingénieur’@fr

* Correlation’@en|‘Corrélation’@fr

• Back analysis’@en | ‘Calcul de calage, méthode inverse’@fr

FAQ

GitHub issue

https://github.com/opengeospatial/Geotech/issues/34

3.5.8. Observable Properties

A quality (property, characteristic) of the feature-of-interest that can be observed.
## Realizations

<table><thead><tr><td>Source</td><td>Type</td><td>Link</td><td>Definition</td></tr></thead><tbody><tr><td>BRGM</td><td>Registry</td><td>https://data.geoscience.fr/ncl/ObsProp</td><td>This register contains the observable properties.</td></tr><tr><td>DIGGS</td><td>XML file</td><td>https://www.diggsml.org/dictionaries/DIGGSTestPropertyDefinitions.xml</td><td>This is an XML dictionary file (extension of GML Dictionary) containing the controlled property code, name, definition and associated test procedures for currently adopted observed properties for DOGGS Test and Monitor measurement objects</td></tr></tbody></table>

## Result types

A non-exhaustive list of Observable Properties for geotechnics includes the following.

<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>natural water content</td><td>Ratio of the mass of free water to the mass of dry soil</td><td>Rapport de la masse d'eau sur la masse sèche</td></tr><tr><td>dry density</td><td>Ratio of the mass of solid to the unit total volume</td><td>Rapport de la masse solide sur le volume total</td></tr><tr><td>dry unit weight</td><td>Product of the dry density times the gravity acceleration g</td><td>Produit de la masse volumique sèche par l'accélération de la pesanteur g</td></tr><tr><td>bulk density</td><td>Ratio of the total mass of the soil to the unit total volume</td><td>Rapport de la masse totale sur le volume total</td></tr><tr><td>bulk unit weight</td><td>Product of the bulk density times the gravity acceleration g</td><td>produit de la masse volumique humide par l'accélération de la pesanteur g</td></tr><tr><td>particle density or density of solid particles</td><td>Ratio of the mass of solid to the volume of solid</td><td>Rapport de la masse solide sur le volume de grains solides</td></tr><tr><td>specific gravity</td><td>Product of the particle density times the gravity acceleration g</td><td>Produit de la masse volumique des grains par l'accélération de la pesanteur g</td></tr><tr><td>total porosity</td><td>Ratio of the volume of void to the total volume</td><td>Rapport entre le volume de vide et le volume total</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>void index</td><td>Ratio of the volume of voids to the volume of solid</td><td>Rapport entre le volume de vide et le volume des grains solides</td></tr><tr><td>saturation ratio or degree of saturation</td><td>Ratio of the volume of water to the volume of voids</td><td>Rapport entre le volume de l'eau et le volume des vides</td></tr><tr><td>lithology classification</td><td>The value that describes the lithology as a controlled term (classification code or controlled name), rather than a simply descriptive one.</td><td>Valeur qui décrit la lithologie comme un terme contrôlé (code de classification ou nom contrôlé), plutôt que simplement descriptif.</td></tr><tr><td>lithology description</td><td>Descriptive information about the soil or rock lithology and should be used in conjunction with lithology classification. A lithology description typically includes a description of color, grain size distribution, constituents and field properties (eg. well-graded sand (SW), fine-grained, dark grey, massive, dry, hard).</td><td>Informations descriptives sur la lithologie du sol ou des roches et doivent être utilisées conjointement avec la classification lithologique. Une description lithologique comprend généralement une description de la couleur, de la distribution granulométrique, des constituants et des propriétés du terrain (par exemple, sable bien classé (SW), à grains fins, gris foncé, massif, sec, dur).</td></tr><tr><td>lithology symbol</td><td>A string or numeric value that is used to define a graphic pattern that may be used to symbolize the unit on a borehole log or map.</td><td>Une chaîne ou une valeur numérique utilisée pour définir un motif graphique pouvant être utilisé pour symboliser l'unité sur un journal ou une carte de forage.</td></tr><tr><td>unit name</td><td>The name of the geological or geotechnical unit</td><td></td></tr><tr><td>Atterberg limits</td><td></td><td></td></tr><tr><td>liquid limit</td><td>Water content at which the soil changes from the liquid state to the plastic state</td><td>Teneur en eau pour laquelle le sol passe de l'état liquide à l'état plastique</td></tr><tr><td>plastic limit</td><td>Water content at which the soil changes from the plastic state to a semi-solid state</td><td>Teneur en eau pour laquelle le sol passe de l'état plastique à l'état semi-solide</td></tr><tr><td>plasticity index</td><td>Difference between the liquid limit and the plastic limit</td><td>Différence entre la limite de liquidité et la limite de plasticité</td></tr></tbody></table>
<table><thead><tr><th>Name</th><th>Definition EN</th><th>Definition FR</th></tr></thead><tbody><tr><td>shrinkage limit</td><td>Water content at which the soil changes from a solid state without shrinkage and a solid state with shrinkage</td><td>Teneur en eau pour laquelle le sol passe d'un état solide sans retrait et un état solide avec retrait</td></tr><tr><td><strong>Particle size parameters</strong></td><td></td><td></td></tr><tr><td>methylene blue test value</td><td>weight of methylene blue adsorbed (fixed) to 100g of the fraction 0/50mm of the soil particles</td><td>Masse de bleu de méthylène adsorbée pour 100g de la fraction 0/50mm du sol étudié</td></tr><tr><td>maximal particle diameter</td><td>maximum diameter of particles</td><td>diamètre maximum des grains</td></tr><tr><td>passing</td><td>Mass percentage of grain particles passing through a given sieve size opening, to the total dry mass of the tested sample.</td><td>Pourcentage massique de particules d'un sol traversant un tamis d'ouverture donnée, rapporté à la masse sèche totale de l'échantillon.</td></tr><tr><td>retained</td><td>Mass percentage of grain particles retained on a given sieve size opening, to the total dry mass of the tested sample.</td><td>Pourcentage massique de particules de grains retenues sur une ouverture de tamis de taille donnée, par rapport à la masse sèche totale de l'échantillon testé.</td></tr><tr><td>particle diameter d60</td><td>Particle size such that 60% of the particles by weight are smaller than size</td><td>Diamètre de grains tel que 60% des grains en poids sont plus petits que ce diamètre</td></tr><tr><td>median particle diameter d50</td><td>Particle size such that 50% of the particles by weight are smaller than size</td><td>Diamètre de grains tel que 50% des grains en poids sont plus petits que ce diamètre</td></tr><tr><td>particle diameter d30</td><td>Particle size such that 30% of the particles by weight are smaller than size</td><td>Diamètre de grains tel que 30% des grains en poids sont plus petits que ce diamètre</td></tr><tr><td>particle diameter d10</td><td>Particle size such that 10% of the particles by weight are smaller than size</td><td>Diamètre de grains tel que 10% des grains en poids sont plus petits que ce diamètre</td></tr><tr><td>boulder content</td><td>Mass percentage of the sample with particles larger than 300 mm or 256 mm depending on classification system used.</td><td>Pourcentage massique de l'échantillon avec des particules supérieures à 300 mm ou 256 mm selon le système de classification utilisé.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>cobble content</td><td>Mass percentage of the sample with particle sizes between 75 and 300 mm or between 64 and 256 mm depending on classification system used.</td><td>Pourcentage massique de l'échantillon avec des granulométries comprises entre 75 et 300 mm ou entre 64 et 256 mm selon le système de classification utilisé.</td></tr><tr><td>pebble content</td><td>Mass percentage of the sample with particle sizes between 4 and 64 mm.</td><td>Pourcentage massique de l'échantillon avec des tailles de particules comprises entre 4 et 64 mm.</td></tr><tr><td>gravel content</td><td>Mass percentage of the sample with particle sizes between 4.75 and 75 mm, or greater than 2 mm, depending on the classification system used.</td><td>Pourcentage massique de l'échantillon dont la granulométrie est comprise entre 4,75 et 75 mm, ou supérieure à 2 mm, selon le système de classification utilisé.</td></tr><tr><td>granule content</td><td>Mass percentage of the sample with particle sizes between 2 and 4 mm</td><td>Pourcentage massique de l'échantillon dont la granulométrie est comprise entre 2 et 4 mm.</td></tr><tr><td>sand content</td><td>Mass percentage of the sample with particle sizes between 0.075 and 4.75 mm, or between than 0.625 and 2 mm, depending on the classification system used.</td><td>Pourcentage massique de l'échantillon avec des tailles de particules comprises entre 0,075 et 4,75 mm, ou entre 0,625 et 2 mm, selon le système de classification utilisé.</td></tr><tr><td>un</td><td>Mass percentage of the sample with particle sizes between 2 and 4.75 mm.</td><td>Pourcentage massique de l'échantillon avec des tailles de particules comprises entre 2 et 4,75 mm.</td></tr><tr><td>medium sand content</td><td>Mass percentage of the sample with particle sizes between 0.425 mm and 2 mm.</td><td>Pourcentage massique de l'échantillon avec des tailles de particules comprises entre 0,425 mm et 2 mm.</td></tr><tr><td>fine sand content</td><td>Mass percentage of the sample with particle sizes between 0.075 and 0.425 mm</td><td>Pourcentage massique de l'échantillon avec des tailles de particules comprises entre 0,075 et 0,425 mm</td></tr><tr><td>silt content</td><td></td><td></td></tr><tr><td>clay content</td><td>Mass percentage of the sample smaller than 0.002 mm</td><td>Pourcentage massique de l'échantillon inférieur à 0,002 mm</td></tr></tbody></table>
<table><thead><tr><th>Name</th><th>Definition EN</th><th>Definition FR</th></tr></thead><tbody><tr><td>fines content</td><td>Mass percentage of the sample smaller than 0.075 mm or 0,0625 mm depending on the classification system used</td><td>Poucentage massique de particule passant par le tamis de 0,063 mm</td></tr><tr><td>uniformity coefficient (or hazen coefficient)</td><td>Ratio of d60/d10.</td><td>Rapport des diamètres d60/d10</td></tr><tr><td><strong>Geochemical parameters</strong></td><td></td><td></td></tr><tr><td>carbonate content</td><td>Percentage of equivalent calcium carbonate obtained from the amount of CO2, as percentage of dry weight.</td><td>Pourcentage massique de la fraction carbonatée contenue dans un sol rapportée au poids du sol sec</td></tr><tr><td>sulfate content</td><td>Amount of sulfate (expressed as SO42-) in milligrams per kilogram of dry soil.</td><td>Concentration en sulfate (exprimée sous la forme SO42-), en milligrams par kilogramme de sol séché à l'air.</td></tr><tr><td>organic matter content</td><td>Ratio of the mass of organic matter in a soil sample by the total solid particle mass.</td><td>Quotient de la masse de matière organique contenues dans un échantillon de sol par la masse des particules solides</td></tr><tr><td>gtr class</td><td>Soil class as per French GTR guidelines or NF P11-300 standard</td><td>classe de sol au sens du GTR (Guide des terrassements routiers) et de la norme NF P 11-300</td></tr><tr><td><strong>Mechanical parameters of soils</strong></td><td></td><td></td></tr><tr><td>uniaxial compressive strength</td><td>The maximum axial compressive stress that a right-cylindrical sample of material can withstand under unconfined conditions—the confining stress is zero. Also known as unconfirmed compressive strength.</td><td>Contrainte de compression axiale maximale à laquelle un échantillon de matériau cylindrique droit peut résister dans des conditions non confinées : la contrainte de confinement est nulle. Également connue sous le nom de résistance à la compression non confirmée.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>shear strength</td><td>Maximum value of the shear stress that a soil can support before it fails along a shear plane, when it is submitted to a deviator of stresses. The shear strength is usually expressed by the Coulomb criterion τ = c + σ.tgφ, with c, the cohesion, and φ, the friction angle.</td><td>Valeur de la contrainte de cisaillement maximale que le sol peut supporter, avant la rupture par glissement le long d'un plan, lorsqu'il est soumis à un déviateur des contraintes. Selon le critère de Coulomb, la résistance au cisaillement d'un sol est τ = c + σ.tgφ, avec c, la cohésion, et φ, l'angle de frottement.</td></tr><tr><td>undrained shear strength</td><td>Value of the shear stress at failure of a cohesive soil, under undrained loading conditions.</td><td>Valeur de la contrainte ou taux de cisaillement à la rupture dans un sol cohérent, en conditions de chargement non drainées</td></tr><tr><td>undrained friction angle</td><td>Value of the friction angle of a soil under undrained loading conditions (null for a saturated cohesive soil)</td><td>Valeur de l'angle de frottement d'un sol, en conditions de chargement non drainées (égal à 0 pour un sol cohérent saturé)</td></tr><tr><td>drained cohesion</td><td>Value of the shear strength of a soil, for a null normal stress, under drained loading conditions</td><td>Valeur de la résistance au cisaillement d'un sol pour une contrainte normale nulle, en conditions de chargement drainées</td></tr><tr><td>drained friction angle</td><td>Value of the friction angle of a soil under drained loading conditions</td><td>Valeur de l'angle de frottement d'un sol, en conditions de chargement drainées</td></tr><tr><td>residual cohesion</td><td>Value of cohesion for high displacements on a failure plane.</td><td>Valeur de la cohésion après de grands déplacements sur une surface de rupture.</td></tr><tr><td>residual friction angle</td><td>Value of friction angle for high displacements on a failure plane.</td><td>Valeur de l'angle de frottement après de grands déplacement sur une surface de rupture</td></tr><tr><td>soil compressibility parameters</td><td></td><td></td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>compression index cc</td><td>Gradient of the linear portion of the oedometer test curve (void ratio versus the logarithm of vertical effective stress), beyond the pressure of pre-consolidation.</td><td>Pente de la partie linéaire de la courbe oedométrique (indice de vides en fonction du logarithme de la contrainte verticale effective), lors du chargement, pour une contrainte verticale appliquée supérieure à la pression de consolidation.</td></tr><tr><td>unloading / recompression index cs (or cg)</td><td>Gradient of the linear portion of the oedometer test curve (void ratio versus the logarithm of vertical effective stress), before the pressure of pre-consolidation.</td><td>Pente de la partie linéaire de la courbe oedométrique (indice de vides en fonction du logarithme de la contrainte verticale effective), lors du chargement pour une contrainte verticale appliquée inférieure à la pression de consolidation ou lors du déchargement.</td></tr><tr><td>consolidation pressure (or yield stress)</td><td>Highest value of vertical effective stress applied on a soil in its geological history. In an oedometer test, vertical effective pressure at the intersection of the reloading and first loading linear portions.</td><td>Contrainte effective verticale la plus élevée à laquelle un sol a été soumis au cours de son histoire géologique. Dans un essai oedométrique, contrainte effective verticale à l'intersection de la droite de recompression réelle et de la droite de compression normale.</td></tr><tr><td>coefficient of vertical consolidation</td><td>Parameter which relates the degree of consolidation to time from the start of consolidation.</td><td>Paramètre qui relie le degré de consolidation au temps écoulé depuis le début de la consolidation.</td></tr><tr><td>creep coefficient</td><td>The ratio of the change in height to the initial height over one log cycle of time during the secondary compression phase.</td><td>Rapport entre la variation de hauteur et la hauteur initiale de l'éprouvette au cours de la compression secondaire.</td></tr><tr><td>swelling index cg</td><td>Gradient of the linear portion of the void ratio versus the logarithm of vertical effective stress curve, during unloading.</td><td>Pente de la courbe oedométrique (indice de vides en fonction du logarithme de la contrainte verticale effective), lors du déchargement.</td></tr></tbody></table>
<table><thead><tr><th>Name</th><th>Definition EN</th><th>Definition FR</th></tr></thead><tbody><tr><td>swelling pressure</td><td>Vertical pressure necessary to maintain a constant volume (i.e to prevent absorption of water) when a soil is saturated.</td><td>Pression nécessaire pour maintenir un volume constant (c'est-à-dire pour empêcher l'absorption d'eau) dans un sol saturé.</td></tr><tr><td>pressuremeter test parameters</td><td></td><td></td></tr><tr><td>menard limit pressure</td><td>Pressure that characterizes the failure of the soil during the Ménard pressuremeter test. It corresponds conventionally to the pressure that leads to double the volume of the tested cavity.</td><td>Pression caractérisant la rupture du sol lors de l'essai pressiométrique Ménard. Par convention, elle correspond à la pression qui entraîne le doublement du volume de la cavité initiale.</td></tr><tr><td>net limit pressure</td><td>Ménard limit pressure to which the total horizontal stress at tested depth is substracted.</td><td>Pression limite de l'essai pressiométrique à laquelle on déduit la contrainte totale horizontale à la profondeur de l'essai.</td></tr><tr><td>menard creep pressure</td><td>Pressure that characterizes the limit between the pseudo-elastic and the plastic behaviour of the soil, during the Ménard pressuremeter test.</td><td>Pression caractérisant la limite entre le comportement élastique et le comportement plastique du sol, lors de l'essai pressiométrique.</td></tr><tr><td>net creep pressure</td><td>Ménard creep pressure to which the total horizontal stress at tested depth is substracted.</td><td>Pression de fluage à laquelle on déduit la contrainte horizontale totale à la profondeur de l'essai</td></tr><tr><td>menard pressuremeter modulus</td><td>Deformation modulus during the pseudo-elastic phase of the Ménard pressuremeter test.</td><td>Module de déformation du sol mesuré lors de l'essai pressiométrique pendant la phase pseudo-élastique de l'essai.</td></tr><tr><td>Static penetration test parameters</td><td></td><td></td></tr><tr><td>cone resistance</td><td>Ratio of the axial load Qc divided by the total area of the cone basis Ac.</td><td>Rapport de la force axiale mesurée Qc divisée par l'aire totale de la base du cône Ac.</td></tr><tr><td>sleeve friction</td><td>The sleeve friction is determined by the force required to push the sleeve through the soil</td><td>Frottement latéral mesuré sur le manchon</td></tr></tbody></table>
<table><thead><tr><th>Name</th><th>Definition EN</th><th>Definition FR</th></tr></thead><tbody><tr><td>friction ratio</td><td>Ratio of the lateral side friction divided by the cone resistance, both measured at the same depth.</td><td>Rapport entre le frottement latéral mesuré sur le manchon et la résistance de pointe, les deux étant réalisés à la même profondeur.</td></tr><tr><td>piezocone pore pressure</td><td>Fluid pressure measured in the filter element placed an the cone basis, during the cone penetration.</td><td>Pression mesurée dans l'élément filtrant au cours des essais de pénétration au cône.</td></tr><tr><td>Dynamic penetration test parameters</td><td></td><td></td></tr><tr><td>N value</td><td>Value of a Standard Penetration Test (SPT) defined as the number of blows exerted by the hammer to achieve a penetration of the last 30 cm, on a total penetration of 45 cm.</td><td>Nombre de coups de battage d'un carottier SPT pour s'enfoncer des 30 derniers cm, lors d'une passe de 45 cm.</td></tr><tr><td>N60</td><td>Calculated value that corrects the value of the Standard Penetration Blow Count (N-value), to account for energy of the hammer (specifically normalized to 60% energy).</td><td>Valeur calculée qui corrige la valeur du nombre de coups de pénétration standard (valeur N), pour tenir compte de l'énergie du marteau (spécifiquement normalisée à 60 % d'énergie).</td></tr><tr><td>N1,60</td><td>Calculated value that corrects the value of the Standard Penetration Blow Count (N), to account for energy of the hammer (specifically normalized to 60% energy) and specific overburden conditions (specifically to an overburden stress of 1 ton per square foot).</td><td>Valeur calculée qui corrige la valeur du nombre de coups de pénétration standard (N), pour tenir compte de l'énergie du marteau (spécifiquement normalisée à 60 % d'énergie) et des conditions de surcharger spécifiques (en particulier pour une contrainte de surcharger de 1 tonne par pied carré).</td></tr><tr><td>first increment spt number of blows n1</td><td>Number of blows exerted by the hammer to achieve a penetration of a first increment of 15 cm.</td><td>Nombre de coups de battage d'un carottier SPT pour s'enfoncer d'un premier incrément de 15 cm</td></tr><tr><td>second increment spt number of blows n2</td><td>Number of blows exerted by the hammer to achieve a penetration of a second increment of 15 cm.</td><td>Nombre de coups de battage d'un carottier SPT pour s'enfoncer d'un deuxième incrément de 15 cm</td></tr></tbody></table>
<table><thead><tr><th>Name</th><th>Definition EN</th><th>Definition FR</th></tr></thead><tbody><tr><td>third increment spf number of blows</td><td>Number of blows exerted by the hammer to achieve a penetration of a third increment of 15 cm.</td><td>Nombre de coups de battage d'un carottier SPT pour s'enfoncer d'un troisième incrément de 15 cm</td></tr><tr><td>driveset blowcount</td><td>Number of blows exerted by the hammer in this driveset to achieve a given penetration into the soil</td><td></td></tr><tr><td>driveset penetration</td><td>Penetraton distance into the soil that is achieved given a specific driveset blowcount</td><td></td></tr><tr><td>driveset index</td><td>A number that defines the specific increment number for a driveset, which consist of a blowcount paired with the penetration achieved. The first driveset has an index of 1, the second, 2 and so on.</td><td></td></tr><tr><td colspan="3"><strong>Rock mechanics parameters</strong></td></tr><tr><td>unconfined compressive strength</td><td>Ratio between the force applied during fracture of the cylindrical test piece and the area of the cross section determined before the test</td><td>Rapport entre la force appliquée lors de la rupture de l'éprouvette cylindrique et l'aire de la section transversale déterminée avant essai</td></tr><tr><td>young modulus</td><td>The Young modulus is the ratio between the normal stress and the axial strain in a linear elastic and isotropic medium.</td><td>Le module d'Young est le rapport entre la contrainte normale et la déformation axiale, dans un matériau élastique linéaire isotrope.</td></tr><tr><td>poisson coefficient</td><td>The Poisson's ratio is a measure of the deformation of a material in direction perpendicular to the specific direction of loading.</td><td>Le coefficient de Poisson est le rapport entre la déformation latérale et la déformation dans l'axe du chargement</td></tr><tr><td>tensile strength (brazilian test)</td><td>Ratio between the force applied during fracture of the cylindrical test piece and the area of the cross section determined before the test. It is an indirect measurement of tensile strength.</td><td>Rapport entre l'effort de compression appliqué le long d'un diamètre d'une éprouvette cylindrique, et la surface du plan de rupture.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>tensile strength (franklin point load test)</td><td>Ratio between the punctual force applied on both sides of a cylindrical test piece and the area of the cross section determined before the test. It is an indirect measurement of tensile strength.</td><td>Rapport entre l'effort de compression ponctuel de part et d'autre du diamètre d'une éprouvette cylindrique, et la surface du plan de rupture. Il s'agit d'une mesure indirecte de résistance à la traction.</td></tr><tr><td>hoek &amp; brown coefficient mi</td><td>Constant introduced by Hoek &amp; Brown ranging from 4 (for some clayey rocks) to more than 30 (for igneous and some metamorphic rocks), used in the Hoek &amp; Brown parabolic failure criterion.</td><td>Constante introduite par Hoek 1 Brown, variant entre 4 (pour les roches argileuses) et plus de 30 (pour les roches ignées et métamorphiques), utilisée dans le critère de rupture de Hoek &amp; Brown.</td></tr><tr><td>hardness (cerchar)</td><td>Index characterising the resistance to penetration of a rock by a drill bit under standard test conditions.</td><td>Indice traduisant la résistance à la pénétration d'un foret dans une roche sous des conditions de chargement normalisées</td></tr><tr><td>abrasivity index (cerchar)</td><td>Index characterising the ability of a rock to cause wear of cutting tool.</td><td>Indice caractérisant la capacité d'une roche à causer l'usure des outils de coupe du rocher.</td></tr><tr><td>los angeles index</td><td>Index characterising the fragmentability of a rock material under mechanical actions. Percentage of the initial sample reduced to a size less than 1.6mm during its rotation in a cylinder loaded with steel balls</td><td>Indice traduisant la fragmentabilité d'une roche sous l'effet d'une usure mécanique. Il correspond au rapport de la masse initiale d'un échantillon de roche sur la masse des fragments de moins de 1,6 mm de diamètre, produit par la rotation de l'échantillon dans un cylindre rempli de billes d'acier.</td></tr><tr><td>micro-deval index</td><td>Index characterising the fragmentability of a rock material under mechanical actions. Percentage of the initial sample reduced to a size less than 1.6mm during its rotation in a cylinder loaded with an abrasive charge</td><td>Indice traduisant la fragmentabilité d'une roche sous l'effet d'une usure mécanique. Il correspond au rapport de la masse initiale d'un échantillon de roche sur la masse des fragments de moins de 1,6 mm de diamètre, produit par la rotation de l'échantillon dans un cylindre avec une charge abrasive.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>core recovery</td><td>Ratio in percent of the length of core recovered to the total length of the core drilled on a given run.</td><td>Rapport en pourcent de la longueur de carotte récupérée à la sortie du carottier sur la longueur de la passe de carottage.</td></tr><tr><td>rqd rock quality designation</td><td>The cumulative length of cores with a length greater than 10 cm, divided by the total length of the core pass with a length greater than or equal to 1m, in percent.</td><td>Longueur cumulée des tronçons de carottes de longueur supérieure à 10cm, divisée par la longueur totale de la passe carottée de longueur supérieure ou égale à 1m, exprimée en pourcent.</td></tr><tr><td>weathering grade</td><td>Level of weathering of a rock mass determined by visual observation, on a scale between I (sound rock) to VI (completely weathered rock - residual soil).</td><td>Niveau d'altération d'un massif rocheux déterminé par observation visuelle, sur une échelle de I (roche saine) à VI (roche totalement décomposée - sol résiduel)</td></tr><tr><td>gsi : geological strength index</td><td>Empirical index introduced by E.Hoek, derived from the RMR and Barton-Q indices, and that characterises the quality of the rock mass.</td><td>Indice empirique introduit par E.Hoek déterminé à partir des indices RMR et Q-Barton, permettant de caractériser la qualité du massif rocheux.</td></tr><tr><td>rmr : rock mass rating</td><td>Index developed by Bieniawski, to provide an quantitative estimate of the quality of a rock mass. RMR is equal to the sum of the six following ratings : 1. Strength of intact rock rating 2. RQD rating 3. Spacing of discontinuities rating 4. Conditions of dic discontinuities rating 5. Groundwater condition rating 6. Adjustment for orientation of discontinuities Bieniawski (1989)</td><td>Indice proposé par Bieniawski, permettant de fournir une évaluation quantitative de la qualité d'un massif rocheux. Le RMR est la somme des six notes suivantes : 1. Note "résistance de la matrice rocheuse" 2. Note RQD 3. Note "espacement des discontinuités" 4. Note "Conditions des dic discontinuités" 5. Note "Conditions hydrauliques" 6. Ajustement selon l'orientation des discontinuités. Bieniawski (1989)</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>q-barton index</td><td>Index introduced by Barton, tha tprovides an quantitative estimate of the quality of rock mass. It is calculated from 6 parameters : . Le RQD . Jn : Joint set number . Jr Joint roughness number . Ja : Joint alteration number . Jw : Joint water reduction factor . SRF : Stress reduction factor</td><td>Indice introduit par Barton qui fournit une estimation quantitative de la qualité du massif rocheux à partir de 6 paramètres : . Le RQD . Jn : Joint set number . Jr Joint roughness number . Ja : Joint alteration number . Jw : Joint water reduction factor . SRF : Stress reduction factor</td></tr><tr><td>discontinuity</td><td>In rock mechanics, any mechanical crack or fissure in a rock mass having a null or a much lower strength than the rock matrix.</td><td>En mécanique des roches, toute fissure ou joint au sein d'un massif rocheux ayant une résistance nulle ou faible comparativement à la résistance de la matrice rocheuse.</td></tr><tr><td>type of discontinuity set</td><td>Type of the discontinuity set, for example : bedding plane, schistosity, etc.</td><td>Type de discontinuité. Par exemple : joint de stratification, diaclase, schistosité, etc.</td></tr><tr><td>strike</td><td>The geographic direction of the discontinuity plane in space with respect to the North.</td><td>Direction géographique d'une ligne créée par l'intersection du plan de la discontinuité avec le plan horizontal.</td></tr><tr><td>dip angle</td><td>The angle that a rock unit, fault or other structure makes with a horizontal plane. The angle is measured in a plane perpendicular to the strike of the rock structure.</td><td>Angle d'une surface (formation géologique, faille, ou autre structure) avec le plan horizontal. Sa mesure est celle du plongement de la ligne de plus grande pente de cette surface.</td></tr><tr><td>spacing</td><td>The perpendicular distance between adjacent discontinuities in a set.</td><td>Distance entre deux discontinuités les plus proches d'une même famille mesurée perpendiculairement à celles-ci.</td></tr><tr><td>interval between discontinuity (id index)</td><td>The mean of the intact rock legnth between successive discontinuities along a survey line whose length and orientation must be recorded.</td><td>Moyenne des intervalles découpés par les discontinuités successives le long d'une ligne de mesure, dont il convient de préciser la longueur et l'orientation.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>extension</td><td>The total area of the discontinuity in all directions.</td><td>L'extension ou la persistence des discontinuités correspond à la surface totale de la discontinuité dans l'espace.</td></tr><tr><td>aperture</td><td>Size of the gap between the joint walls of the discontinuity, measured perpendicularly to the joint plane</td><td>Distance entre épontes comptée perpendiculairement au plan de discontinuité.</td></tr><tr><td>roughness</td><td>Qualifies the surface irregularities on the joint walls of a discontinuity, from very rough to slickensided.</td><td>La rugosité qualifie les irrégularités de surface des épontes d'une discontinuité. Elle varie de : surface très rugueuse à lustrée.</td></tr><tr><td>joint roughness coefficient (jrc)</td><td>Dimensionless coefficient relating to joint roughness and size, ranked in ascending order from 0 for a flat smooth discontinuity to 20 for a wavy rough discontinuity, according to Barton's standard profiles (1977).</td><td>Coefficient sans dimension relié à la rugosité et à la taille des épontes ; il varie entre 0 (pour une discontinuité planne et lisse) à 20 (pour une discontinuité ondulée et rugueuse), selon la classification établie par Barton (1977).</td></tr><tr><td>infill</td><td>The nature of the material filling the discontinuity or coating the walls.</td><td>Nature du matériau de remplissage ou de l'enduit des épontes.</td></tr><tr><td>shear strength</td><td>Value of the shear stress at failure. For a discontinuity, the shear strength is usually expressed by the Coulomb criterion τ = c + σ.tgφ, with c, the cohesion, and φ, the friction angle.</td><td>Valeur de la contrainte de cisaillement à la rupture. Pour une discontinuité, la résistance au cisaillement est exprimée par le critère de Coulomb : τ = c + σ.tgφ, avec c, la cohésion, et φ, l'angle de frottement.</td></tr><tr><td>cohesion</td><td>Shear stress at failure, for a normal stress equal to zero. For a discontinuity, appraent cohesion which does not express an intrinsic property of the joint wall material but the influence of irregularities in the walls on shear behaviour.</td><td>Contrainte de cisaillement à la rupture pour une contrainte normale nulle. Pour une discontinuité, il s'agit d'une cohésion apparente et non une propriété intrinsèque du matériau de remplissage du joint, cette cohésion caractérisant l'influence des irrégularités de surfaces des épontes.</td></tr></tbody></table>
<table><thead><tr><th>Name</th><th>Definition EN</th><th>Definition FR</th></tr></thead><tbody><tr><td>friction angle</td><td>Friction angle of the discontinuity that depends on the rock nature, the roughness of joint walls and the weathering grade on the walls.</td><td>Angle de frottement du joint dépendant de la nature pétrographique, de la rugosité de la surface et du dégré d'altération des épontes.</td></tr><tr><td>normal stiffness</td><td>In an uniaxial compression tests on joints oriented perpendicular to the direction of load application, slope of the curve of normal stress versus normal displacement, .</td><td>Lors d'un essai de compression simple, dirigé perpendiculairement au joint de discontinuité, pente de la courbe de la contrainte normale en fonction du déplacement normal.</td></tr><tr><td>tangential stiffness</td><td>In a shear test on joints, slope of the curve of tangential stress versus tangential displacement.</td><td>Lors d'un essai de cisaillement direct le long d'une discontinuité, pente de la courbe contrainte tangentielle en fonction du déplacement tangential.</td></tr><tr><td>compression wave velocity</td><td>Ratio of the propagation time of a compression wave in an elastic body medium between two points divided by the distance between these points</td><td>Rapport de la durée de propagation d'une onde de compression entre deux points dans un milieu élastique, divisé par la distance entre ces deux points</td></tr><tr><td>shear wave velocity</td><td>Ratio of the propagation time of a shear wave in an elastic body medium between two points divided by the distance between these points</td><td>Rapport de la durée de propagation d'une onde de cisaillement entre deux points dans un milieu élastique, divisé par la distance entre ces deux points</td></tr><tr><td colspan="3"><strong>Geo-hydraulics parameters</strong></td></tr><tr><td>darcy's permeability</td><td>Parameter that characterizes the ability of a porous (continuous) medium to be crossed by a fluid, to a flow from the same direction</td><td>Paramètre caractérisant l'aptitude d'un milieu poreux (continu) à se laisser traverser par un fluide, vis-à-vis d'un flux de même direction.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>intrinsic permeability</td><td>Parameter characterizing a porous medium isotropic, which measures its permeability to a homogeneous fluid arbitrary, regardless of the characteristics of the fluid. Volume of kinematic viscosity unit fluid flowing through in a unit of time, under the effect of a unit of potential gradient, one unit surface orthogonal to the direction of flow. It can be expressed in darcy's</td><td>Paramètre caractérisant un milieu poreux isotrope, qui mesure sa perméabilité vis-à-vis d'un fluide homogène quelconque, indépendamment des caractéristiques du fluide. Volume de fluide d'unité de viscosité cinématique qui traverse en une unité de temps, sous l'effet d'une unité de gradient de potentiel, une unité de surface orthogonale à la direction du flux. Il est exprimable en darcy's.</td></tr><tr><td>packer test - lugeon unit</td><td>1 Lugeon unit is equivalent to 1 liter of water flow per meter of tested zone, per minute, under a pressure of 1 MPa.</td><td>1 unité Lugeon équivaut à 1 litre d'eau prélevé par mètre de longueur d'essai, par minute, sous une pression de 1 MPa.</td></tr><tr><td>transmissivity</td><td>Parameter governing the flow of water flowing per unit width of the saturated zone of a continuous aquifer (measured in a direction orthogonal to that of flow), and per unit of hydraulic gradient</td><td>Paramètre régissant le débit d'eau qui s'écoule par unité de largeur de la zone saturée d'un aquifère continu (mesurée selon une direction orthogonale à celle de l'écoulement), et par unité de gradient hydraulique.</td></tr><tr><td>storage coefficient</td><td>Ratio of the volume of water released or stored per unit area of an aquifer, to the corresponding charge in hydraulic head, without reference to time</td><td>Rapport du volume d'eau libérée ou emmagasinée par unité de surface d'un aquifère, à la variation de charge hydraulique correspondante, sans référence au temps (ou en un temps illimité).</td></tr><tr><td>specific storage coefficient</td><td>Volume of water released or stored per unit area of an aquifer, to the corresponding charge in hydraulic head, without reference to time</td><td>Volume d'eau libérée ou emmagasinée par unité de volume du milieu aquifère, par unité de variation de charge hydraulique correspondante, sans référence au temps.</td></tr></tbody></table>
<table><thead><tr><td>Name</td><td>Definition EN</td><td>Definition FR</td></tr></thead><tbody><tr><td>piezometric level</td><td>Upper level of the static liquid column that balances the hydrostatic pressure at the point to which it relates. It is materialized by the free level of the water in a vertical tube open at the point considered (piezometer).</td><td>Niveau supérieur de la colonne liquide statique qui équilibre la pression hydrostatique au point auquel elle se rapporte. Il est matérialisé par le niveau libre de l'eau dans un tube vertical ouvert au point considéré (piézomètre).</td></tr></tbody></table>

### 3.5.9. MaterialSample

A MaterialSample is a physical, tangible Sample.

#### Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC OMS</td><td>MaterialSample</td><td>A MaterialSample is a physical, tangible Sample.</td></tr><tr><td>IFC</td><td>MaterialSample</td><td>Same as OGC OMS</td></tr><tr><td>AGS</td><td>SAMP</td><td>SAMP includes information for both the sample and the sampling activity</td></tr><tr><td>DIGGS</td><td>Sample</td><td>A material sample, either solid, fluid, or gas that is obtained as a result of a sampling activity, for the purpose of observation and/or testing. This is a concrete representation of AbstractSample, which serves as the head of a substitution group for this and other sample specialties.</td></tr><tr><td>DIGGS</td><td>TrialGroutBatch</td><td>A specialization of Sample that also contains properties describing the characteristics of a batch of grout developed for testing to determine a grout design mix.</td></tr></tbody></table>
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>DIGGS</td><td>GroutBatch</td><td>A specialization of Sample that contains properties describing the characteristics of a batch of grout used for production purposes. This object must reference a DesignGroutMix object defined within the GroutingProgram feature.</td></tr><tr><td>DIGGS</td><td>AbstractSpecimen</td><td>AbstractSpecimen serves as the head of a substitution group for specimen specializations based on state or type: eg. soil, liquid, gas, rock. A specimen derives from one or more samples, is created as part of a test procedure, and exists only in the context of the test procedure that creates it.</td></tr><tr><td>DIGGS</td><td>GroutSpecimen</td><td>A specialization of a specimen that describes the physical conditions of a grout or concrete sample subjected to testing.</td></tr><tr><td>DIGGS</td><td>FluidSpecimen</td><td>A specialization of a specimen that describes the physical conditions of a fluid sample or samples subjected to testing.</td></tr><tr><td>DIGGS</td><td>RockSpecimen</td><td>A specialization of a specimen that describes the physical conditions of a rock sample or samples subjected to testing.</td></tr><tr><td>DIGGS</td><td>SoilSpecimen</td><td>A specialization of a specimen that describes the physical conditions of a soil sample or samples subjected to testing.</td></tr></tbody></table>

## Properties

## FAQ

### What about Specimen?

In geotechnics, a distinction may appear between the MaterialSample collected on the field and another MaterialSample made from it by sub-sampling. The first one is often called Sample, while the second(s) is/are often called Specimen(s).
Here in this conceptual model, the term MaterialSample is generic and can be used for both. Attributes can be used to explain the lineage between two (or more) MaterialSample.

Standards like DIGGS yet propose an explicit terminology.

## What about Sampling?

The sampling activity can be described with [Sampling]

## GitHub issue

https://github.com/opengeospatial/Geotech/issues/11

## 3.5.10. Sampling and Preparation

Sampling is an act applying a SamplingProcedure to create or transform one or more MaterialSamples.

Sampling Procedure is a description of steps performed by a Sampler in order to extract a Sample from its sampledFeature in the frame of a Sampling.

Preparation Procedure is the description of preparation steps performed on a Sample.

## Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC OMS</td><td>Sampling</td><td>Sampling is an act applying a SamplingProcedure to create or transform one or more Sample(s).</td></tr><tr><td>OGC OMS</td><td>SamplingProcedure</td><td>Sampling Procedure is a description of steps performed by a Sampler in order to extract a Sample from its sampledFeature in the frame of a Sampling.</td></tr><tr><td>OGC OMS</td><td>PreparationProcedure</td><td>Sampling is an act applying a SamplingProcedure to create or transform one or more Sample(s).</td></tr><tr><td>AGS</td><td>SAMP</td><td>SAMP includes information for both the sample and the sampling activity</td></tr></tbody></table>
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>DIGGS</td><td>SamplingActivity</td><td>The action taken to obtain or produce material samples even if the activity fails to produce a sample (eg. a core run that produces no recovery). The activity type must be specified, and indicates if the produced sample(s) are a result of collection at a sampling feature, sub-sampling, aggregation of two or more samples, or a sample created as a test or blank sample. All samples must refer to a SamplingActivity feature. SamplingActivity is restricted to the collection or creation of a new material sample, or a subsampling or aggregation of existing collected or created samples. The activity of transforming a material sample into a specimen that is being tested is described in the preparationProcedure property of a specimen object that derives from an existing material sample.</td></tr><tr><td>DIGGS</td><td>AbstractSpecimen</td><td>AbstractSpecimen serves as the head of a substitution group for specimen specializations based on state or type: eg. soil, liquid, gas, rock. A specimen derives from one or more samples, is created as part of a test procedure, and exists only in the context of the test procedure that creates it.</td></tr></tbody></table>

## Properties

### 3.6. Book B Principles

In their tentative to appreciate the environment of a projected infrastructure, geotechnical engineers pay attention to several aspects:
* Geology,

* HydroGeology,

* Geotechnics,

* Surrounding constructions,

* Geohazards, and

* Environmental impact (polluted site).

Models are built in order to reflect an understanding of this environment.

Each Book B ends with a register of uncertainties: what is known, what is unknown.

### 3.6.1. Concepts list

The Book B is organized in Geomodels which themselves are components of different Features based on their thematic content.

### 3.6.2. Primary models and their components

The following components are included in geology, hydrogeology, and geotechnics models.

* Geomodel

* GeologicUnit

* Fault

* Contact

* Fold

* HydroGeoUnit

* FluidBody

* FluidBodySurface

* GeotechUnit

* DiscreteDiscontinuity

* Void

* HazardArea

* SurroundingConstruction

### 3.6.3. GeoModel

A Geomodel is a simplified view of a model. A model is defined as the result of geoscience data processing or interpretation. Proposing either a spatial distribution of geoscientific objects with properties of interest (feature) or attempt of retranscribing natural/man-made behavior through mathematical functions or algorithms (process).
## Realization

<table><thead><tr><th>Data model</th><th>Concept name</th><th>Definition</th></tr></thead><tbody><tr><td>OGC EPOS</td><td>ModelView</td><td>Simplified view of a Model. A model is defined as the result of geoscience data processing or interpretation. Proposing either a spatial distribution of geoscientific objects with properties of interest (feature) or attempt of retranscribing natural/man-made behavior through mathematical functions or algorithms (process).</td></tr><tr><td>IFC</td><td></td><td></td></tr><tr><td>AGSi</td><td>agsiModel</td><td>A digital geometric (1D, 2D or 3D) representation of the ground. There are potentially many different types of model covering different categories (conceptual, observational, analytical) and domains (geological, geotechnical, hydrogeological, geoenvironmental, etc.).</td></tr></tbody></table>

## Github issue

https://github.com/opengeospatial/Geotech/issues/26

### 3.6.4. GeologicUnit

Conceptually, a GeologicUnit may represent a body of material in the Earth whose complete and precise extent is inferred to exist (e.g., North American Data Model GeologicUnit, Stratigraphic unit in the sense of NACSN, or International Stratigraphic Code), or a classifier used to characterize parts of the Earth (e.g., lithologic map unit like 'granitic rock' or 'alluvial deposit', surficial units like 'till' or 'old alluvium'). It includes both formal units (i.e., formally adopted and named in an official lexicon) and informal units (i.e., named but not promoted to a lexicon) and unnamed units (i.e., recognizable, described and delineable in the field but not otherwise formalized). In simpler terms, a geologic unit is a package of earth material (generally rock).

## Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GeoSciML</td><td>GeologicUnit</td><td>Conceptually, a GeologicUnit may represent a body of material in the Earth whose complete and precise extent is inferred to exist (e.g., North American Data Model GeologicUnit, Stratigraphic unit in the sense of NACSN, or International Stratigraphic Code), or a classifier used to characterize parts of the Earth (e.g., lithologic map unit like 'granitic rock' or 'alluvial deposit', surficial units like 'till' or 'old alluvium'). It includes both formal units (i.e., formally adopted and named in an official lexicon) and informal units (i.e., named but not promoted to a lexicon) and unnamed units (i.e., recognizable, described and delineable in the field but not otherwise formalized). In simpler terms, a geologic unit is a package of earth material (generally rock).</td></tr><tr><td>IFC</td><td>GeologicUnit</td><td>Same as OGC GeoSciML</td></tr><tr><td>DIGGS</td><td>StratigraphyObservation</td><td>Descriptions of ordered bodies of rock or soil, such as formations, biostratigraphic units or aquifers.</td></tr><tr><td>AGSi</td><td>agsiModelElement</td><td>In AGSi a model is collection of elements (agsiModelElement object) and this may include geological units, identified as such (or as a specialization) using the elementType attribute.</td></tr></tbody></table>

Specializations (Types of GeologicUnit)
<table><thead><tr><td>Source</td><td>Type</td><td>Link</td><td>Definition</td></tr></thead><tbody><tr><td>BRGM</td><td>Registry</td><td>https://data.geoscience.f r/ncl/GeolUnitType</td><td>This register lists all the geologic units.</td></tr><tr><td>CGI</td><td>Registry</td><td>https://cgi.vocabs.gd go.au/object? uri=http%3A// resource.geosciml.org/ classifier/cgi/ geologicunittype</td><td>This register lists all the geologic units.</td></tr></tbody></table>

* allostratigraphic unit

* alteration unit

* artificial ground

* biostratigraphic unit

* chronostratigraphic unit

* deformation unit

* excavation unit

* geomorphologic unit

* geophysical unit

* lithodemic unit

* lithogenetic unit

* lithologic unit

* lithostratigraphic unit

* lithotectonic unit

* magnetostratigraphic unit

* mass movement unit

* pedoderm

* pedostratigraphic unit

* polarity chronostratigraphic unit

## Properties

<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>Identifier</td><td>The identifier should have the same value as the corresponding GeoSciML MappedFeature identifier, if available.</td></tr></tbody></table>
<table><thead><tr><td>Pro pert yNa me</td><td>Definition</td></tr></thead><tbody><tr><td>Nam e</td><td>name is a display name for the GeologicUnit.</td></tr><tr><td>Desc ripti on</td><td>description is a description of the GeologicUnit, typically taken from an entry on a geological map legend.</td></tr><tr><td>geol ogic Unit Type</td><td>geologicUnitType contains the type of GeologicUnit (as defined in GeoSciML). To report an identifier from a controlled vocabulary, geologicUnitType_uri shall be used.</td></tr><tr><td>rank</td><td>rank contains the rank of GeologicUnit (as defined by ISC. e.g., group, formation, member).</td></tr><tr><td>repr esen tativ eLit holo gy</td><td>description of the GeologicUnit's lithology, possibly formatted with formal syntax (see 8.9.2.3). The description can be language-dependent. To report an identifier from a controlled vocabulary, representativeLithology_uri shall be used.</td></tr><tr><td>repr esen tativ eAge</td><td>description of the age of the GeologicUnit (where age is a sequence of events and may include process and environment information). To report an identifier from a controlled vocabulary, representativeAge_uri, representativeOlderAge_uri, representativeYoungerAge_uri shall be used.</td></tr><tr><td>num eric Olde rAge</td><td>a numerical representation of the unit's older age in million years (Ma).</td></tr><tr><td>num eric You nger Age</td><td>a numerical representation (Primitive::Number) of the unit's younger age in million years (Ma).</td></tr><tr><td>obse rvati onM etho d</td><td>a metadata snippet indicating how the spatial extent of the feature was determined. ObservationMethod is a convenience property that provides a simple approach to observation metadata when data are reported using a feature view (as opposed to observation view).</td></tr></tbody></table>
<table><thead><tr><th>Property Name</th><th>Definition</th></tr></thead><tbody><tr><td>source</td><td>If present, the property source:Primitive::CharacterString is human readable text describing feature-specific details and citations to source materials, and if available provides URLs to reference material and publications describing the geologic feature. This could be a short text synopsis of key information that would also be in the metadata record referenced by metadata_uri.</td></tr><tr><td>metadataURI</td><td>If present, the property metadata_uri:Primitive::CharacterString contains a URI referring to a metadata record describing the provenance of data.</td></tr><tr><td>shape</td><td>The property shape:GEO::GM_Objects contains a geometry defining the extent of the feature of interest.</td></tr><tr><td>positionalAccuracy</td><td>If present, the property positionalAccuracy:Primitive::CharacterString is a quantitative value (a numerical value and a unit of length) defining the radius of an uncertainty buffer around a MappedFeature (e.g., a positionalAccuracy of 100 m for a line feature defines a buffer polygon of total width 200 m centred on the line).</td></tr><tr><td>geologicalFormation</td><td>ISO14689:2017</td></tr><tr><td>faciesLiterature</td><td>The characteristics of a rock or a sediment unit that reflect its environment of deposition and allow it to be distinguished from rock or sediment deposited in an adjacent environment.</td></tr><tr><td>faciesPetrography</td><td>A rock mass that can be recognized by its composition, structures or fossil content and mapped on the basis of those characteristics.</td></tr></tbody></table>

## FAQ

**What about Hydrogeologic Units?**

They are a type of GeologicUnit and are described in HydrogeoUnit
### 3.6.5. Fault

A fault includes all brittle to ductile style structures along which displacement has occurred, from a simple, single ‘planar’ brittle or ductile surface to a fault system comprised of tens of strands of both brittle and ductile nature. This structure may have some significant thickness (a deformation zone) and have an associated body of deformed rock that may be considered a deformation unit (which geologicUnitType is ‘DeformationUnit’) which can be associated to the ShearDisplacementStructure using GeologicFeatureRelation from the GeoSciML Extension package

#### Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GeoSciML</td><td>ShearDisplacementStructure</td><td>A shear displacement structure includes all brittle to ductile style structures along which displacement has occurred, from a simple, single ‘planar’ brittle or ductile surface to a fault system comprised of tens of strands of both brittle and ductile nature. This structure may have some significant thickness (a deformation zone) and have an associated body of deformed rock that may be considered a deformation unit (which geologicUnitType is ‘DeformationUnit’) which can be associated to the ShearDisplacementStructure using GeologicFeatureRelation from the GeoSciML Extension package.</td></tr><tr><td>IFC</td><td>Fault</td><td>Same as OGC</td></tr><tr><td>AGSi</td><td>agsiModelElement</td><td>In AGSi a model is collection of elements (agsiModelElement object) and this may include elements representing geological structure such as faults, identified as such using the elementType attribute.</td></tr></tbody></table>
## Properties

<table><thead><tr><td>Property</td><td>Definition</td></tr></thead><tbody><tr><td>identifier</td><td>Globally unique identifier:Primitive::CharacterString shall uniquely identifies a tuple within the dataset and be formatted as an absolute URI conformant to RFC 3986.</td></tr><tr><td>name</td><td>name contains a display name for the ShearDisplacementStructure.</td></tr><tr><td>description</td><td>description contains a human readable text description of the ShearDisplacementStructure, typically taken from an entry on a geological map legend.</td></tr><tr><td>faultType</td><td>faultType contains a human readable description of the type of ShearDisplacementStructure (as defined in GeoSciML). To report an identifier from a controlled vocabulary, faultType_uri shall be used.</td></tr><tr><td>movementType</td><td>movementType contains a human readable summary of the type of movement (e.g., dip-slip, strike-slip) on the ShearDisplacementStructure. To report an identifier from a controlled vocabulary, movementType_uri shall be used.</td></tr><tr><td>deformationStyle</td><td>deformationStyle contain a human readable description of the style of deformation (e.g., brittle, ductile etc.) for the ShearDisplacementStructure. To report an identifier from a controlled vocabulary, deformationStyle_uri shall be used.</td></tr><tr><td>displacement</td><td>displacement contains a text summarizing the displacement across the ShearDisplacementStructure.</td></tr><tr><td>geologicHistory</td><td>geologicHistory contains a text, possibly formatted with formal syntax, describing the age of the ShearDisplacementStructure (where age is a sequence of events and may include process and environment information).</td></tr></tbody></table>
<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>observationMethod</td><td>observationMethod contains a metadata snippet indicating how the spatial extent of the feature was determined. ObservationMethod is a convenience property that provides a quick and dirty approach to observation metadata when data are reported using a feature view (as opposed to observation view).</td></tr><tr><td>numericOlderAge</td><td>numericOlderAge reports the older age of the fault/shear structure, represented million years (Ma).</td></tr><tr><td>numericYoungerAge</td><td>numericYoungerAge reports the younger age of the fault/shear structure, represented million years (Ma).</td></tr><tr><td>source</td><td>source contains a text describing feature-specific details and citations to source materials, and if available providing URLs to reference material and publications describing the geologic feature. This could be a short text synopsis of key information that would also be in the metadata record referenced by metadata_uri.</td></tr><tr><td>metadatauri</td><td>If present, the property metadata_uri:Primitive::CharacterString contains a URI referring to a metadata record describing the provenance of data.</td></tr><tr><td>shape</td><td>The property shape:GM_Object contains a geometry defining the extent of the feature of interest.</td></tr><tr><td>positionalAccuracy</td><td>If present, the property positionAccuracy:Primitive::CharacterString contains quantitative representation defining the radius of an uncertainty buffer around a MappedFeature (e.g., a positionalAccuracy of 100 m for a line feature defines a buffer polygon of total width 200 m centred on the line).</td></tr></tbody></table>
<table><thead><tr><td>Property</td><td>Definition</td></tr></thead><tbody><tr><td>Fault Activity</td><td>Qualitative rating of the fault activity. A fault that has slipped in historic time and which is likely to slip again in the future.</td></tr><tr><td>Fault Area</td><td>GT1R1A1</td></tr><tr><td>Fault Length</td><td>Fault length (L) is the longest horizontal or subhorizontal dimension along the fault plane</td></tr><tr><td>Fault Depth</td><td>Fault depth is the depth where no further relative displacement is recorded</td></tr><tr><td>Fault Infill</td><td>Substance interspersed between the wall surfaces of a discontinuity (JGS) generally, the material occupying the space between joint surfaces, faults, and other rock discontinuities. The filling material may be clay, gouge, various natural cementing agents, or alteration products of the adjacent rock.(ASTM, ISRM)</td></tr><tr><td>Fault Direction</td><td>The geographic direction of a line created by the intersection of a plane and the horizontal plane. If non specific convention is used, this angular value is in the range 0 to 18 degrees. In this case, there is an ambiguity on the dip orientation. For example, a plane with an orientation of 90 degrees from the north could either have a dip direction to the North or to the South. Thus, to avoid this ambiguity, a strike value is generally completed with an indication of the dip orientation (Quadrant).</td></tr><tr><td>Fault Slip Direction</td><td>Observed relative displacement direction of the hanging wall (top) to the footwall, e.g., up. Down, left, right or combinations (like top down - left)</td></tr><tr><td>Fault Plane</td><td>angle between the strike of the slip surface and the slip vector (striation)</td></tr></tbody></table>
<table><thead><tr><th>Property</th><th>Definition</th></tr></thead><tbody><tr><td>Fault</td><td>the vertical displacement between the Hanging wall and Footwall</td></tr><tr><td>Fault Line</td><td>the horizontal displacement between the Hanging wall and Footwall.</td></tr><tr><td>Fault Plane</td><td>The horizontal displacement between points on either side of a fault, which can range from millimeters to kilometers.</td></tr><tr><td>Fault Plane Offset</td><td>offset of beds parallel to fault</td></tr><tr><td>Fault Dip</td><td>offset of beds parallel to dip</td></tr><tr><td>Fault Strike</td><td></td></tr></tbody></table>

## GitHub issue

https://github.com/opengeospatial/Geotech/issues/20

## 3.6.6. Contact

A contact is a general concept representing any kind of surface separating two geologic units, including primary boundaries such as depositional contacts, all kinds of unconformities, intrusive contacts, and gradational contacts, as well as faults that separate geologic units.

## Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GeoSciML</td><td>Contact</td><td>A contact is a general concept representing any kind of surface separating two geologic units, including primary boundaries such as depositional contacts, all kinds of unconformities, intrusive contacts, and gradational contacts, as well as faults that separate geologic units.</td></tr><tr><td>IFC</td><td>Contact</td><td>Same as OGC GeoSciML</td></tr></tbody></table>

## Properties

<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>identifier</td><td>Globally unique identifier:Primitive::CharacterString shall uniquely identifies a tuple within the dataset and be formatted as an absolute URI conformant to RFC 3986.</td></tr><tr><td>name</td><td>name reports the display name for the Contact.</td></tr><tr><td>description</td><td>description reports the description of the Contact, typically taken from an entry on a geological map legend.</td></tr><tr><td>contactType</td><td>contactType reports the type of Contact (as defined in GeoSciML) as a human readable label. To report an identifier from a controlled vocabulary, contactType_uri shall be used.</td></tr></tbody></table>
<table><thead><tr><th>Property Name</th><th>Definition</th></tr></thead><tbody><tr><td>observationMethod</td><td>observationMethod reports a metadata snippet indicating how the spatial extent of the feature was determined. ObservationMethod is a convenience property that provides a quick and simple approach to observation metadata when data are reported using a feature view (as opposed to observation view).</td></tr><tr><td>positionalAccuracy</td><td>positionalAccuracy reports quantitative values defining the radius of an uncertainty buffer around a MappedFeature (e.g., a positionalAccuracy of 100 m for a line feature defines a buffer polygon of total width 200 m centred on the line).</td></tr><tr><td>source</td><td>source contains a text describing feature-specific details and citations to source materials, and if available providing URLs to reference material and publications describing the contact feature. This could be a short text synopsis of key information that would also be in the metadata record referenced by metadata_uri.</td></tr><tr><td>metadata_uri</td><td>metadata_uri reports a URI referring to a metadata record describing the provenance of data.</td></tr><tr><td>genericSymbolizer</td><td>genericSymbolizer contains an identifier for a symbol from standard (locally or community defined) symbolization scheme for portrayal.</td></tr></tbody></table>
<table><thead><tr><th>Property Name</th><th>Definition</th></tr></thead><tbody><tr><td>Shape</td><td>The property shape:GMObject contains a geometry defining the extent of the contact feature.</td></tr><tr><td>Direction</td><td>The geographic direction of a line created by the intersection of a plane and the horizontal plane. If non specific convention is used, this angular value is in the range 0 to 18 degrees. In this case, there is an ambiguity on the dip orientation. For example, a plane with an orientation of 90 degrees from the north could either have a dip direction to the North or to the South. Thus, to avoid this ambiguity, a strike value is generally completed with an indication of the dip orientation (Quadrant).</td></tr></tbody></table>

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/8

### 3.6.7. Fold

A fold is formed by one or more systematically curved layers, surfaces, or lines in a rock body. A fold denotes a structure formed by the deformation of a geologic structure, such as a contact which the original undeformed geometry is presumed, to form a structure that may be described by the translation of an abstract line (the fold axis) parallel to itself along some curvilinear path (the fold profile). Folds have a hinge zone (zone of maximum curvature along the surface) and limbs (parts of the deformed surface not in the hinge zone). Folds are described by an axial surface, hinge line, profile geometry, the solid angle between the limbs, and the relationships between adjacent folded surfaces if the folded structure is a Layering fabric.

### Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GeoSciML</td><td>Fold</td><td>A fold is formed by one or more systematically curved layers, surfaces, or lines in a rock body. A fold denotes a structure formed by the deformation of a geologic structure, such as a contact which the original undeformed geometry is presumed, to form a structure that may be described by the translation of an abstract line (the fold axis) parallel to itself along some curvilinear path (the fold profile). Folds have a hinge zone (zone of maximum curvature along the surface) and limbs (parts of the deformed surface not in the hinge zone). Folds are described by an axial surface, hinge line, profile geometry, the solid angle between the limbs, and the relationships between adjacent folded surfaces if the folded structure is a Layering fabric.</td></tr><tr><td>IFC</td><td>Fold</td><td>Same as OGC GeoSciML</td></tr></tbody></table>

## Properties

<table><thead><tr><td>Property</td><td>Definition</td></tr></thead><tbody><tr><td>profile type</td><td>FoldProfileType contains a term from a controlled vocabulary specifying the concave/convex geometry of fold relative to earth surface, and relationship to younging direction in folded strata if known. (e.g., antiform, synform, neutral, anticline, syncline, monocline, ptygmatic).</td></tr><tr><td>amplitude</td><td>The amplitude property reports the length from line segment connecting inflection points on adjacent fold limbs to the intervening fold hinge.</td></tr></tbody></table>
<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>axial surface</td><td>The property axialSurfaceOrientation is used to characterize the geometry of a fold. The axial surface of a particular fold may be located based on observations of the folded geologic structure, but in general it has no direct physical manifestations. As a geologic surface, it has geometric properties, including orientation, which may be specified by observations at one or more locations, or generalized using terminology (upright, inclined, reclined, recumbent, overturned). Dip and Dip Direction are one approach to specifying the value.</td></tr><tr><td>genetic model</td><td>The property geneticModel contains a term from a controlled vocabulary describing the specification of genetic model for fold, e.g., flexural slip, parallel.</td></tr><tr><td>hinge line curvature</td><td>The hingeLineCurvature property contains a term from a controlled vocabulary that describes the variation in orientation of fold hinge along trend of fold, distinguishing sheath from cylindrical folds (e.g., sheath, dome, basin, cylindrical).</td></tr><tr><td>hinge line orientation</td><td>The property hingeLineOrientation reports the specification of the hinge line orientation for fold. GSML_LinearOrientation allows for a term value specification or a numeric specification of either or both the trend and plunge of hinge line. Hinge plunge term examples: sub-vertical, steeply plunging, sub-horizontal, reclined and vertical for special cases in which hinge plunge is close to axial surface dip. 0..* cardinality allows for both a numeric specification and a term specification.</td></tr><tr><td>hinge shape</td><td>The property hingeShape reports a term from a controlled vocabulary describing the hinge shape, e.g., Rounded vs. angular hinge zones. This property has to do with the proportion of the wavelength that is considered part of hinge.</td></tr><tr><td>interlimb angle</td><td>The property interLimbAngle contains a term from a controlled vocabulary describing the interlimb angle using a tightness term (e.g., gentle (120-180°), open (70-120°), close (30-70°), tight (10-30°), isoclinal (0-10°)).</td></tr><tr><td>limb shape</td><td>The limbShape property contains a term from a controlled vocabulary describing the shape of the limb (e.g., straight vs curved limbs, kink, chevron, sinusoidal, box).</td></tr><tr><td>span</td><td>The span property reports a value describing the linear distance between inflection points in a single fold.</td></tr></tbody></table>
<table><thead><tr><th>Property</th><th>Definition</th></tr></thead><tbody><tr><td>symmetry</td><td>The symmetry property contains a term from a controlled vocabulary describing the concordance or discordance of bisecting surface and axial surface, or the ratio of length of limbs. The folded surface may have asymmetry defined by limb length ratio if inflection points are defined. The definition based on bisecting surface/axial surface angle depends on having multiple surfaces defined such that the axial surface may be identified (symmetric, asymmetric).</td></tr><tr><td>Dip Direction</td><td>The geographic direction of a line created by the intersection of a plane and the horizontal plane. If non specific convention is used, this angular value is in the range 0 to 18 degrees. In this case, there is an ambiguity on the dip orientation. For example, a plane with an orientation of 90 degrees from the north could either have a dip direction to the North or to the South. Thus, to avoid this ambiguity, a strike value is generally completed with an indication of the dip orientation (Quadrant).</td></tr></tbody></table>

## FAQ

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/9

### 3.6.8. HydrogeoUnit

These are distinct volumes of earth material that serve as containers for subsurface fluids. The boundaries of a unit are typically discriminated from those of another unit using properties related to the potential or actual ability to contain or move water. The properties can be geological or hydraulic, and typically include influences from the surrounding hydrological environment. More specifically, the conceptual model delineates two types of hydrogeological units, with slightly different orientations: aquifer-related units have boundaries delimited by the hydrogeological properties of the rock body, while groundwater basins have boundaries delimited by distinct flow regimes. Aquifer-related units are subdivided into aquifer systems, which are collections of aquifers, confining beds, and other aquifer systems. Confining beds are units that impede water flow to surrounding units, and supersede notions such as aquitards, aquicludes, and aquifuges, which are not included herein, as it is difficult to differentiate these in practice.
## Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GWML2</td><td>HydrogeoUnit</td><td>Any soil or rock unit or zone that by virtue of its hydraulic properties has a distinct influence on the storage or movement of groundwater.</td></tr><tr><td>IFC</td><td>HydrogeoUnit</td><td>Same as OGC GWML2</td></tr><tr><td>AGSi</td><td>agsiModelElement</td><td>In AGSi a model is collection of elements (agsiModelElement object) and this may include hydrogeological units, identified as such using the elementType attribute.</td></tr></tbody></table>

## Properties

Inherited properties from the GeologicUnit concept

See GeologicUnit

## Specific properties

<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>Identifier</td><td>Globally unique identifier shall uniquely identifies a tuple within the dataset and be formatted as an absolute URI conformant to RFC 3986.</td></tr><tr><td>Name</td><td>name contains a display name for the HydroGeoUnit.</td></tr><tr><td>gwUnitDescription</td><td>Description of the unit.</td></tr><tr><td>gwUnitMetadata</td><td>Metadata for the unit.</td></tr><tr><td>gwUnitName</td><td>Name of the unit (common local name or formal name).</td></tr><tr><td>gwUnitThickness</td><td>Typical thickness of the unit.</td></tr><tr><td>gwUnitMetadata</td><td>Type of material or, by proximity, type of voids (e.g., granular, fracture, karstic, or mixed).</td></tr><tr><td>gwUnitRecycle</td><td>Volumetric flow rate of water that enters an hydrogeologic unit, at potentially multiple locations.</td></tr></tbody></table>
<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>gwUnitDis charge</td><td>Volumetric flow rate of water that goes out of an hydrogeologic unit, at potentially multiple locations.</td></tr><tr><td>gwUnitWa terBudget</td><td>Sum of water input and output of a hydrogeologic unit, at a particular point in time, with a description of inflows and outflows.</td></tr><tr><td>gwUnitVul nerability</td><td>The susceptibility of the aquifer to specific threats such as various physical events (earthquakes), human processes (depletion), etc.</td></tr><tr><td>gwUnitSha pe</td><td>The geometry of the unit.</td></tr><tr><td>LinkToAn Observatio nAPI</td><td></td></tr><tr><td>Permeabili tyHoz</td><td>value of horizontal permeability</td></tr><tr><td>Permeabili tyvert</td><td>value of vertical permeability</td></tr><tr><td>Transmiss ivity</td><td>Parameter governing the flow of water flowing per unit width of the saturated zone of a continuous aquifer (measured in a direction orthogonal to that of flow), and per unit of hydraulic gradient</td></tr><tr><td>Storage coefficient</td><td>Ratio of the volume of water released or stored per unit area of an aquifer, to the corresponding charge in hydraulic head, without reference to time</td></tr><tr><td>Specific storage</td><td>Volume of water released or stored per unit area of an aquifer, to the corresponding charge in hydraulic head, without reference to time</td></tr><tr><td>EffectiveP orosity</td><td>Ratio of the volume of gravitational water that a medium porous may contain in a state of saturation then release under the effect of complete drainage (laboratory drainage on a sample), to its total volume</td></tr><tr><td>IntrinsicPe rmeability Direction</td><td>direction of intrinsic permeability</td></tr><tr><td>IntrinsicPe rmeability Value</td><td>value of intrinsic permeability</td></tr><tr><td>Hydraulic FlowVeloc ity</td><td>Fictitious macroscopic speed of a water flow in uniform movement through a saturated aquifer medium (speed vector of Darcy's law) deduced from the flow rate referred to the total section of the aquifer crossed by the flow</td></tr><tr><td>InitialWat erSaturati on</td><td>In situ state, initial water saturation level (before construction)</td></tr></tbody></table>
### 3.6.9. FluidBody

These are distinct bodies of fluid (liquid or gas) that fill the voids in hydrogeological units. Fluid bodies are made of biologic (e.g., organisms), chemical (e.g., solutes), or material constituents (e.g., sediment). While it is expected that the major constituent of a fluid body will be water, the conceptual model allows for other types of major constituents such as petroleum. Minor constituents are not necessarily fluids, but can be gases, liquids, or solids (including organisms), and are included in the fluid body in various forms of mixture, such as solution, suspension, emulsion, and precipitates. Fluid bodies can also have other fluid bodies as parts, such as plumes or gas bubbles. Surfaces can be identified on a fluid body, such as a water table, piezometric or potentiometric surface, and some such surfaces can contain divides, which are lines projected to the fluid surface denoting divergence in the direction of flow systems within the fluid.

#### Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GWML2</td><td>FluidBody</td><td>These are distinct bodies of fluid (liquid or gas) that fill the voids in hydrogeological units. Fluid bodies are made of biologic (e.g., organisms), chemical (e.g., solutes), or material constituents (e.g., sediment). While it is expected that the major constituent of a fluid body will be water, the conceptual model allows for other types of major constituents such as petroleum. Minor constituents are not necessarily fluids, but can be gases, liquids, or solids (including organisms), and are included in the fluid body in various forms of mixture, such as solution, suspension, emulsion, and precipitates. Fluid bodies can also have other fluid bodies as parts, such as plumes or gas bubbles. Surfaces can be identified on a fluid body, such as a water table, piezometric or potentiometric surface, and some such surfaces can contain divides, which are lines projected to the fluid surface denoting divergence in the direction of flow systems within the fluid.</td></tr><tr><td>IFC]</td><td>FluidBody</td><td>Same as OGC GWML2</td></tr><tr><td>AGSi</td><td>agsiModelElement</td><td>In AGSi a model is collection of elements (agsiModelElement object) and this may include fluid bodies, identified as such using the elementType attribute.</td></tr></tbody></table>

FAQ
### 3.6.10. FluidBodySurface

A surface on a fluid body within a local or regional area, e.g., piezometric, potentiometric, water table, salt wedge, etc.

#### Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC GWML2</td><td>FluidBodySurface</td><td>A surface on a fluid body within a local or regional area, e.g. piezometric, potentiometric, water table, salt wedge, etc.</td></tr><tr><td>IFC</td><td>PiezometricWaterLevel</td><td>Same as OGC GWML2</td></tr><tr><td>AGSi</td><td>agsiModelElement</td><td>In AGSi a model is collection of elements (agsiModelElement object) and this may include a fluid body surface, e.g. piezometric surface, identified as such using the elementType attribute.</td></tr></tbody></table>

#### FAQ

### 3.6.11. GeotechnicalUnit

A surface or a volume in which the mechanical behavior and other design-relevant characteristics are characterized using the same geotechnical parameters values. Several alternative classifications can be required in a project for different design tasks.

#### Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>IFC</td><td>GeotechUnit</td><td>A surface or a volume in which the mechanical behavior and other design-relevant characteristics are characterized using the same geotechnical parameters values. Several alternative classifications (=GeotechModels) can be required in a project for different design tasks.</td></tr><tr><td>OGC GeoSciML</td><td>GeotechUnit (as a GeologicUnit with Type = GeotechnicalUnit)</td><td>Same as IFC 4.4+</td></tr><tr><td>DIGGS</td><td>GeoUnitObservation</td><td>Descriptions of a soil or rock where the unit is primarily defined by the value(s) or a value range of one or more physical or engineering properties. The criteria for distinguishing such units may vary depending on the engineering application.</td></tr><tr><td>AGSi</td><td>agsiModelElement</td><td>In AGSi a model is collection of elements (agsiModelElement object) and this may include geotechnical units, identified as such using the elementType attribute.</td></tr></tbody></table>

## Properties

The GeotechUnit concept distinguishes SoilLikeMaterial and IntactRockMaterial. Each having its own characteristics. The tables below list relevant properties for those types of GeotechUnit. Some being interpreted, calculated or derived from measurements.

### Inherited properties from the GeologicUnit concept

See GeologicUnit

### Relevant properties for soil like material

### Relevant properties for intact rock

### Discontinuities in rock
<table><thead><tr><td>Property name</td><td>Definition</td></tr></thead><tbody><tr><td>RQD</td><td>Quotient of the cumulative length of cores with a length greater than 10 cm, by the total length of the core pass with a length greater than or equal to 1m</td></tr><tr><td>DiscontinuityType</td><td>pattern of bedding, folds, faults and discontinuities in rock masses, which subdivide the mass into individual domains or rock blocks (ISO14689)</td></tr><tr><td>DiscontinuityStrikeDirection</td><td>The geographic direction of a line created by the intersection of a plane and the horizontal plane. If non specific convention is used, this angular value is in the range 0 to 18 degrees. In this case, there is an ambiguity on the dip orientation. For example, a plane with an orientation of 90 degrees from the north could either have a dip direction to the North or to the South. Thus, to avoid this ambiguity, a strike value is generally completed with an indication of the dip orientation (Quadrant).</td></tr><tr><td>DiscontinuityDipAngle</td><td>The dip is the steepest angle of descent of a géological plane to a horizontal plane. It's value its in the range 0 to 90 degrees.</td></tr><tr><td>DiscontinuitySpacing</td><td>The term “spacing” refers to the mean or modal spacing of a set of discontinuities and is the perpendicular distance between adjacent discontinuities. The number of discontinuity sets, the differences in spacing and the angles between the sets shall be reported as these determine the block shape. The discontinuity spacing should be measured in millimeters and can be classified using the terms in Table 8. (ISO14689)</td></tr><tr><td>DiscontinuityPersistence</td><td>The linear extent of discontinuities from their inception to their termination in solid rock mass or against other discontinuities or outside the exposure shall be reported. The size of the exposure shall also be recorded. If possible and appropriate, measurements should be made in two or preferably three orthogonal directions. (ISO14689)</td></tr><tr><td>DiscontinuityAperture</td><td>The perpendicular distance between the two surfaces of a discontinuity is referred to as the aperture. (ISO14689)</td></tr></tbody></table>
<table><thead><tr><td>Property name</td><td>Definition</td></tr></thead><tbody><tr><td>DiscontinuityInfilling</td><td>The infilling material between discontinuity surfaces shall be identified and described (e.g., soil, minerals such as calcite, quartz, epidote, chlorite, anhydrite, clay gouge, rock gouge or breccia). (ISO14689)</td></tr><tr><td>DiscontinuityRoughness</td><td>The surface condition and the shape of discontinuities shall be described on the basis of three scales of observation, respectively, and using the terms given in Table 9 and illustrated in Figure 2: a) small scale (several millimeters) — smooth or rough; b) medium scale (several centimeters) — planar, stepped or undulating; c) large scale (several metres) — straight, curved or wavy. (ISO14689)</td></tr><tr><td>DiscontinuityWaterPresence</td><td>Descriptive of estimated waterinflow in excavation, to be used to define Jw(Barton), or RMR groundnwater inflow rating.</td></tr><tr><td>Cohesion</td><td>Cohesive shear strength of a rock or soil that is independent of interparticle friction.</td></tr><tr><td>FrictionAngle</td><td>Derived from the Mohr-Coulomb failure criterion and used to describe the friction shear resistance of ground materials, together with the normal effective stress.</td></tr></tbody></table>

## Properties for rock mass

### Extra properties

<table><thead><tr><td>Property name</td><td>Definition</td></tr></thead><tbody><tr><td>PwaveVelocity</td><td>Value of S wave (Shear wave (S)) measured through the unit.</td></tr><tr><td>SwaveVelocity</td><td>Value of P wave (pressure or primary elastic body wave (P)) measured through the unit.</td></tr><tr><td>Resistivity</td><td>Electrical resistivity of a rock or soil (Ohm-m).</td></tr><tr><td>GroundwaterTemperature</td><td>Temperature measured or assumed in the groundwater</td></tr><tr><td>WetBulkDensity</td><td>Ratio of the total mass to the unit total volume (material at its natural moisture content)</td></tr><tr><td>DryBulkDensity</td><td>Ratio of the mass of solid to the unit total volume (dry material)</td></tr></tbody></table>
### 3.6.12. DiscreteDiscontinuity

Any interruption of the continuity in the rock material with its attendant mechanical, hydraulic and thermal properties.

## Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>IFC</td><td>DiscreteDiscontinuity</td><td>Any interruption of the continuity in the rock material with its attendant mechanical, hydraulic and thermal properties.</td></tr><tr><td>OGC GeosciML</td><td>Joint</td><td>Fracture across which there is no displacement at the scale of interest.</td></tr><tr><td>DIGGS</td><td>DiscontinuityObservation</td><td>Descriptions of faults, fractures and joints and their spacing, with attendant mechanical and hydraulic properties.</td></tr></tbody></table>

## Properties

<table><thead><tr><td>Property name</td><td>Definition</td></tr></thead><tbody><tr><td>DiscontinuityType</td><td>pattern of bedding, folds, faults and discontinuities in rock masses, which subdivide the mass into individual domains or rock blocks (ISO14689)</td></tr><tr><td>DipDirection</td><td>The azimuth of the dip (dip direction) shall be measured in degrees in the range 0° to 360° counted clockwise from true north and expressed as a three-digit number, e.g., 240 or 015. (ISO14689)</td></tr><tr><td>DipAngle</td><td>The maximum declination (dip) of the mean plane of the discontinuity from the horizontal shall be measured with the clinometer in the range 0° to 90° and should be expressed in degrees as a two-digit number, e.g., 50. (ISO14689)</td></tr></tbody></table>
<table><thead><tr><td>Property name</td><td>Definition</td></tr></thead><tbody><tr><td>Disc ontinuity spacing</td><td>The term “spacing” refers to the mean or modal spacing of a set of discontinuities and is the perpendicular distance between adjacent discontinuities. The number of discontinuity sets, the differences in spacing and the angles between the sets shall be reported as these determine the block shape. The discontinuity spacing should be measured in millimeters and can be classified using the terms in Table 8. (ISO14689)</td></tr><tr><td>Disc ontinuity Perpendicular distance</td><td>The linear extent of discontinuities from their inception to their termination in solid rock mass or against other discontinuities or outside the exposure shall be reported. The size of the exposure shall also be recorded. If possible and appropriate, measurements should be made in two or preferably three orthogonal directions. (ISO14689)</td></tr><tr><td>Disc ontinuity roughness</td><td>The surface condition and the shape of discontinuities shall be described on the basis of three scales of observation, respectively, and using the terms given in Table 9 and illustrated in Figure 2:<br>a) small scale (several millimeters) — smooth or rough;<br>b) medium scale (several centimeters) — planar, stepped or undulating;<br>c) large scale (several metres) — straight, curved or wavy. (ISO14689)</td></tr><tr><td>Disc ontinuity Aperture</td><td>The perpendicular distance between the two surfaces of a discontinuity is referred to as the aperture. (ISO14689)</td></tr><tr><td>Disc ontinuity Infilling</td><td>The infilling material between discontinuity surfaces shall be identified and described (e.g., soil, minerals such as calcite, quartz, epidote, chlorite, anhydrite, clay gouge, rock gouge or breccia). (ISO14689)</td></tr><tr><td>Disc ontinuity Water seepage</td><td>Free moisture or water flow visible at individual spots or from discontinuities</td></tr><tr><td>Cohesion</td><td>Cohesive shear strength of a rock or soil that is independent of interparticle friction.</td></tr></tbody></table>
<table><thead><tr><th>Property name</th><th>Definition</th></tr></thead><tbody><tr><td>Friction Angle</td><td>Derived from the Mohr-Coulomb failure criterion and used to describe the friction shear resistance of ground materials, together with the normal effective stress.</td></tr></tbody></table>

## FAQ

### How to deal with DiscontinuitySets in a GeotechnicalUnit?

A description of the sets of discontinuities can be described as properties of a GeotechnicalUnit.

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/23

## 3.6.13. Void

Voids are the spaces inside a unit (e.g., aquifer) or its material (e.g., the sandstone material of an aquifer), and might contain fluid bodies. Voids are differentiated from porosity, in that porosity is a ratio of void volume to total volume of unit plus voids, while voids are the spaces themselves. It is important to conceptually differentiate voids from units and their containers, in order to represent, for example, the volume of fractures, caves, or pores in a particular unit or its portion.

### Realizations

<table><thead><tr><th>Data model</th><th>Concept name</th><th>Definition</th></tr></thead><tbody><tr><td>OGC GWML2</td><td>HydroGeoVoid</td><td>Voids are the spaces inside a unit (e.g., aquifer) or its material (e.g., the sandstone material of an aquifer), and might contain fluid bodies. Voids are differentiated from porosity, in that porosity is a ratio of void volume to total volume of unit plus voids, while voids are the spaces themselves. It is important to conceptually differentiate voids from units and their containers, in order to represent, for example, the volume of fractures, caves, or pores in a particular unit or its portion.</td></tr></tbody></table>
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>IFC 4.4+</td><td>Void</td><td>Same as OGC GWML2</td></tr></tbody></table>

## Specializations (Types of Voids)

<table><thead><tr><td>Source</td><td>Type</td><td>Link</td><td>Definition</td></tr></thead><tbody><tr><td>BRGM</td><td>Registry</td><td>https://data.geoscience.f r/ncl/CaviTy</td><td>This register lists all the types of cavities. By cavity is meant an empty space in a rocky environment, of millimeter size (microcavities) to multidecametric (cave), filled with a gas or liquid phase.</td></tr></tbody></table>

## FAQ

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/24

## 3.6.14. HazardArea

Discrete spatial objects representing a natural hazard.

### Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC / INSPIRE Theme III: Natural Risk Zones</td><td>Hazard Area</td><td>Discrete spatial objects representing a natural hazard.</td></tr><tr><td>IFC</td><td>HazardArea</td><td>Same as OGC INSPIRE Natural Risk Zone</td></tr></tbody></table>

### Properties

<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>Hazard Type</td><td>A generic classification and a specific classification of the type of hazard.</td></tr></tbody></table>
<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>Likelihood Of Occurrence</td><td>Likelihood is a general concept relating to the chance of an event occurring.</td></tr><tr><td>Level Of Intensity</td><td>An expression of the magnitude or the intensity of a phenomenon.</td></tr><tr><td>validity Period</td><td>Future finite time frame where the hazard applies</td></tr><tr><td>Determination Method</td><td>Different ways to delineate the perimeter of a hazard</td></tr></tbody></table>

## Existing codelist for HazardType

<table><thead><tr><td>Source</td><td>Type</td><td>Link</td><td>Definition</td></tr></thead><tbody><tr><td>INSPIRE</td><td>Codelist</td><td>https://inspire.ec.europa.eu/codelist/NaturalHazardCategoryValue</td><td>A generic classification of types of natural hazards.</td></tr></tbody></table>

## FAQ

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/43

## 3.6.15. Surrounding Construction

Any other construction that may be impacted by the construction of the building or infrastructure.

### Realizations
<table><thead><tr><th>Data model</th><th>Concept name</th><th>Definition</th></tr></thead><tbody><tr><td>OGC LandInfra</td><td>Facility</td><td>Facilities include buildings and civil engineering works and their associated siteworks. Civil engineering works, or infrastructure facilities, are construction works comprising a structure, such as a dam, bridge, road, railway, runway, utilities, pipeline, or sewerage system, or are the result of operations such as dredging, earthwork, and geotechnical processes. A facility has a life cycle, including planning, design, construction, maintenance, operation, and removal phases. The design and construction phases are typically performed as part of a project. There may be multiple such projects during the life cycle of the facility to enable phased construction and incremental improvement.</td></tr><tr><td>IFC</td><td>IFC_Bridge</td><td></td></tr><tr><td>IFC</td><td>IFC_Tunnel</td><td></td></tr><tr><td>IFC</td><td>IFC_Road</td><td></td></tr><tr><td>IFC</td><td>IFC_Building</td><td></td></tr></tbody></table>

And all other relevant facilities and construction the construction would like to pay attention too.

## Properties

<table><thead><tr><th>Property Name</th><th>Definition</th></tr></thead><tbody><tr><td>assessmentOfVulnerability</td><td>Assessment of the vulnerability of the exposed element.</td></tr></tbody></table>

## Existing codelist for HazardType
<table><thead><tr><td>Source</td><td>Type</td><td>Link</td><td>Definition</td></tr></thead><tbody><tr><td>INSPIRE</td><td>Codelist</td><td>https://inspire.ec.europa.eu/codelist/NaturalHazardCategory/Value</td><td>A generic classification of types of natural hazards.</td></tr></tbody></table>

# FAQ

## GitHub issue

https://github.com/opengeospatial/Geotech/issues/43

## 3.7. Book C Principles

Book C starts with a detailed description of the feedback (in civil engineering terms) from prior structures built near or adjacent to similar terrain.

Book C then goes on to summarize the decisive elements – among all those set out in Books B – that have dictated the foundational design choices.

Book C also details the recommended execution methods for each part of the structure ‘Book C’ should also include details of the overall strategy suggested by the project manager for all matters relating to excavated materials A specific chapter should be devoted to neighboring structures Lastly, Book C should present a broad overview of the monitoring methods.

Book C end with the Risk register resulting from the intersection between the uncertainties listed in Book B and the envisaged construction methods.

### 3.7.1. Application

The book C is (linear) infrastructure focused. It provides a summary of the expected conditions and possible risks that may occur during the project construction.

The information that are provided are deeply linked to the targeted infrastructure and its design. Changes on those aspects may considerably alter the validity of the results that are provided.

Remembering AFTES guidelines are tunnel focused, slight adaptation were adopted to make the proposal also applicable to other kind of infrastructure.

### 3.7.2. Concepts list

The core of Book C is the GeotechSynthesisModel

That is mainly composed of:

* Alignment

* GeotechTypicalSection

* RiskZone
### 3.7.3. GeotechSynthesisModel

Link between the design and modeled geology and geotechnical conditions: summarized interpretation with regard to building, construction method,... in relation to a section of the alignment or building structure. Typical definition of "baseline conditions" as usually included in a geotech.

#### Realization

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC EPOS</td><td>ModelView</td><td>Same as IFC</td></tr><tr><td>IFC</td><td>GeotechSynthesisModel</td><td>Link between the design and modeled geology and geotechnical conditions: summarized interpretation with regard to building, construction method, in relation to a section of the alignment or building structure. Typical definition of "baseline conditions" as usually included in a geotech. longitudinal section</td></tr><tr><td>AGSi</td><td>agsiModel</td><td>A digital geometric (1D, 2D or 3D) representation of the ground. There are potentially many different types of model covering different categories (conceptual, observational, analytical) and domains (geological, geotechnical, hydrogeological, geoenvironmental, etc.).</td></tr></tbody></table>

#### FAQ

##### Github issue

https://github.com/opengeospatial/Geotech/issues/26

### 3.7.4. Alignment

PositioningElement which provides a Linear Referencing System for locating PhysicalElements. An Alignment shall be continuous, non-branching, and non-overlapping. If it is a Project Alignment, it is for a single alternative, as specified by its owning ProjectPart.

Note: this concept has been commonly defined between OGC LandInfra and bSI.
## Realizations

<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>OGC LandInfra</td><td>Alignment</td><td>PositioningElement which provides a Linear Referencing System for locating PhysicalElements. An Alignment shall be continuous, non-branching, and non-overlapping. If it is a Project Alignment, it is for a single alternative, as specified by its owning ProjectPart.</td></tr><tr><td>IFC 4.4+</td><td>Alignment</td><td>Same as OGC LandInfra</td></tr></tbody></table>

## FAQ

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/44

## 3.7.5. GeotechTypicalSection

Interval along the alignment/building structure with similar ground conditions, as part of the GeotechSynthesis model that represents the connection between the ground model and the building. Includes key-properties like expected distribution of ground types (reference to GeotechUnits) and baseline-definition of expected ground conditions and potential hazards, and may also include key-information on design like excavation measures, distribution of support types etc.

## Realizations
<table><thead><tr><td>Data model</td><td>Concept name</td><td>Definition</td></tr></thead><tbody><tr><td>IFC</td><td>GeotechTypicalSection</td><td>Interval along the alignment/building structure with similar ground conditions, as part of the GeotechSynthesis model that represents the connection between the ground model and the building. Includes key-properties like expected distribution of ground types (reference to GeotechUnits) and baseline-definition of expected ground conditions and potential hazards, and may also include key-information on design like excavation measures, distribution of support types etc.</td></tr><tr><td>OGC LandInfra</td><td>FacilityPart</td><td>Land and Infrastructure facility, such as a road or bridge. A facility has a life cycle, including planning, design, construction, maintenance, operation, and removal phases The design and construction phases are typically performed as part of a project. There may be multiple such projects during the life cycle of the facility to enable phased construction and incremental improvement.</td></tr><tr><td>ISO 19148</td><td>FeatureEvent</td><td>The FeatureEvent interface is used to linearly reference a feature along a LinearElement and possibly further qualified as applying at an instant in, or during a period of, time.</td></tr></tbody></table>

Note: the GeotechTypicalSection can be seen on different aspect and then have multiple realizations: - a part of a tunnel (a part of a facility) - an event along an alignment.

## Properties
<table><thead><tr><td> PropertyName </td><td> Definition </td></tr></thead><tbody><tr><td> ExpGeotechUnit </td><td> Representative GeotecUnit expected in the subject typical section </td></tr><tr><td> ExpDistGeotechUnits </td><td> Expected distribution of project related “geotechnical units” (= ground types) in subject tunnel section </td></tr><tr><td> DiscontinuitySettings </td><td> Expected Sets of discontinuities, with typical orientation and properties like spacing, persistence etc. </td></tr><tr><td> Overburden </td><td> Range of overburden (distance from tunnel to ground surface) in the subject section </td></tr><tr><td> GroundwaterDesignPressure </td><td> Groundwater pressure to be considered in the design </td></tr><tr><td> GroundwaterInflowSum </td><td> Groundwater inflow measured or expected during a certain time span </td></tr><tr><td> GroundwaterAggressiveness </td><td> Rating of the aggressiveness e.g., towards concrete </td></tr><tr><td> GroundwaterTemperature </td><td> Groundwater temperature observed at specific location or expected in the subject section </td></tr><tr><td> Karst </td><td> Description of expected or observed karst features </td></tr><tr><td> Boulders </td><td> Description of expected or observed boulders features </td></tr><tr><td> GasType </td><td> Type of natural gas occurrence in subject section </td></tr><tr><td> GasConcentration </td><td> Expected concentration of gas to be encountered during excavation </td></tr><tr><td> DumpCategory </td><td> Project-related category for re-use and storage of the excavated material </td></tr><tr><td> Contamination </td><td> Expected anthropogenic contaminations </td></tr><tr><td> InSituStress </td><td> Anisotropic stress regime, with direction and magnitude of principal stresses </td></tr><tr><td> Swelling </td><td> Expected swelling behavior </td></tr><tr><td> GroundTemperature </td><td> Ground temperature expected in the subject section </td></tr><tr><td> CloggingPotential </td><td> Description or rating of the potential for clogging equipment in sticky ground </td></tr><tr><td> AsbestosPotential </td><td> Description or rating of the potential presence of asbestos in the ground </td></tr><tr><td> HeavyMetalsPotential </td><td> Description or rating of the potential presence of heavy metals in the ground </td></tr><tr><td> RiskIdentification </td><td> Name and Description of the risk </td></tr><tr><td> RiskNature </td><td> Description of the nature of the risk </td></tr><tr><td> RiskSource </td><td> Description of the source of the risk related to a specific uncertainty </td></tr></tbody></table>
<table><thead><tr><td> PropertyName </td><td> Definition </td></tr></thead><tbody><tr><td> Event </td><td> Occurrence or change of a particular set of circumstances </td></tr><tr><td> Likelihood </td><td> chance of something happening </td></tr><tr><td> Consequences </td><td> outcome of an event affecting the objectives </td></tr><tr><td> LevelOfRisk </td><td> Magnitude of a risk or combination of risks, expressed in terms of the combination of consequences and their likelihood </td></tr><tr><td> PreventiveTreatment </td><td> Description of the preventive treatment </td></tr><tr><td> LevelOfResidualRisk </td><td> Description of the preventive treatment </td></tr><tr><td> CurativeTreatment </td><td> Description of the curative treatment </td></tr></tbody></table>

## FAQ

### GitHub issue

https://github.com/opengeospatial/Geotech/issues/44

## 3.7.6. RiskZone

Discrete spatial objects representing the spatial extent of a combination of the consequences of an event (hazard) and the associated probability/likelihood of its occurrence.

### Realizations

<table><thead><tr><td> Data model </td><td> Concept name </td><td> Definition </td></tr></thead><tbody><tr><td> OGC / INSPIRE Theme III: Natural Risk Zones </td><td> RiskZone </td><td> Discrete spatial objects representing the spatial extent of a combination of the consequences of an event (hazard) and the associated probability/likelihood of its occurrence. </td></tr><tr><td> IFC </td><td> GeotechTypicalSection </td><td> </td></tr></tbody></table>

Note: In IFC, Risks are infrastructure (tunnel, bridge) focused and their expression is limited to the GeotechTypicalSection

### Properties
<table><thead><tr><td>Property Name</td><td>Definition</td></tr></thead><tbody><tr><td>LevelOrIntensity</td><td>The level of risk is an assessment of the combination of the consequences of an event (hazard) and the associated probability/likelihood of the occurrence of the event.</td></tr></tbody></table>

# FAQ

## GitHub issue

https://github.com/opengeospatial/Geotech/issues/43
# Chapter 4. OGC and ISO models

## 4.1. General mapping

These figures propose an overview of how the geotech concepts are proposed to be realized with existing ISO and OGC standards (with a blue border) but also IFC (with a red border).

Details about the mapping are then provided concept per concept.

### 4.1.1. Model Typology

<figure><img src="image_3.png" /><figcaption>Figure 2. Models</figcaption></figure>

### 4.1.2. For Geological Modeling realization
<figure><img src="image_4.png" /><figcaption>Figure 3. Geological Model realization</figcaption></figure>

### 4.1.3. For Hydrogeological Modeling

<figure><img src="image_5.png" /><figcaption>Figure 4. Hydrogeological Model</figcaption></figure>

### 4.1.4. For Geotechnical Modeling
<figure><img src="image_6.png" /><figcaption>Figure 5. Geotechnical Model</figcaption></figure>

### 4.1.5. For Hazard and Surrounding Construction Modeling

<figure><img src="image_7.png" /><figcaption>Figure 6. Hazard and Surrounding Construction Model</figcaption></figure>

### 4.1.6. For Book C
<figure><img src="image_8.png" /><figcaption>Figure 7. Book C</figcaption></figure>

### 4.1.7. Mapping table summary

<table><thead><tr><th>AFTE<br>S<br>Book</th><th>Geotech<br>concept</th><th>OGC + EPOS + INSPIRE</th><th>With OGC SensorThingsAPI</th></tr></thead><tbody><tr><td>A</td><td>Borehole</td><td>gsml:Borehole</td><td>Either BhCollarThing or BhTrajectoryThing</td></tr><tr><td>A</td><td>BoreholeCollar</td><td>gwml2:BoreCollar</td><td>BhCollarThing</td></tr><tr><td>A</td><td>BoreholeTrajectory</td><td></td><td>BhTrajectoryThing</td></tr><tr><td>A</td><td>The whole borehole</td><td></td><td>BhFeatureOfInterest (with BhFeatureType = Hole &amp; Entirety)</td></tr><tr><td>A</td><td>A part of the borehole</td><td></td><td>BhFeatureOfInterest (with BhFeatureType = Hole &amp; Segment)</td></tr><tr><td>A</td><td>A location in the borehole</td><td></td><td>BhFeatureOfInterest (with BhFeatureType = Hole &amp; Point)</td></tr><tr><td>A</td><td>MaterialSample</td><td>oms://MaterialSample/[oms:Material Sample]</td><td>BhFeatureOfInterest</td></tr><tr><td>A</td><td>Specimen</td><td>oms://MaterialSample/[oms:Material Sample]</td><td>BhFeatureOfInterest (with BhFeatureType = Specimen)</td></tr><tr><td>A</td><td>BoreholeCore</td><td>oms://MaterialSample/[oms:Material Sample]</td><td>BhFeatureOfInterest (with BhFeatureType = Core &amp; Entirety)</td></tr></tbody></table>
<table><thead><tr><th>AFTE<br>S<br>Book</th><th>Geotech<br>concept</th><th>OGC + EPOS + INSPIRE</th><th>With OGC SensorThingsAPI</th></tr></thead><tbody><tr><td>A</td><td>A part of the<br>borehole core</td><td>oms://MaterialSample/[oms:Material<br>Sample]</td><td>BhFeatureOfInterest (with<br>BhFeatureType = Core & Segment or<br>Point)</td></tr><tr><td>A</td><td>A location of<br>the borehole<br>core</td><td>oms://MaterialSample/[oms:Material<br>Sample]</td><td>BhFeatureOfInterest (with<br>BhFeatureType = Core & Point)</td></tr><tr><td>A</td><td>Environmental<br>MonitoringFacility</td><td>ef:environmentalMonitoringFacility</td><td>Sensor</td></tr><tr><td>A</td><td>Observation</td><td>oms:observation</td><td></td></tr><tr><td>A</td><td>Geotech test</td><td>oms:observationCollection</td><td>Sensor</td></tr><tr><td>A</td><td>Series of<br>observations</td><td>oms:observationCollection</td><td>Stream</td></tr><tr><td>A</td><td>Individual<br>observation</td><td>oms:observation</td><td>Observation</td></tr><tr><td>A</td><td>Sampling</td><td>oms://Sampling/[oms:Sampling]</td><td>BhSampling</td></tr><tr><td>B</td><td>Geomodel</td><td>epos:ModelView</td><td></td></tr><tr><td>B</td><td>GeologicUnit</td><td>gsml:GeologicUnit (with<br>GeologicUnitType =<br>LithoStratigraphicUnit])</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>Contact</td><td>gsml:Contact</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>Fold</td><td>gsml:Fold</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>Hydrogeounit</td><td>gwml2:HydroGeoUnit</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>FluidBody</td><td>gwml2:FluidBody</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>FluidBodySurface</td><td>gwml2:FluidBodySurface</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>Fault</td><td>gsml:ShearDisplacementStructure</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>GeotechnicalUnit</td><td>gsml:GeologicUnit (with<br>GeologicUnitType = GeotechUnit])</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>DiscreteDiscontinuity</td><td>gsml:Joint</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>Void</td><td>gwml2:HydroGeoVoid</td><td>BhFeatureOfInterest</td></tr><tr><td>B</td><td>HazardArea</td><td>nz:HazardArea</td><td>BhFeatureOfInterest</td></tr><tr><td>C</td><td>Alignment</td><td>landinfra:Alignment</td><td>BhFeatureOfInterest</td></tr><tr><td>C</td><td>GeotechSynthesisModel</td><td>epos:ModelView</td><td>BhFeatureOfInterest</td></tr></tbody></table>
<table><thead><tr><th>AFTE<br>S<br>Book</th><th>Geotech<br>concept</th><th>OGC + EPOS + INSPIRE</th><th>With OGC SensorThingsAPI</th></tr></thead><tbody><tr><td>C</td><td>GeotechTypical<br>Section</td><td>landinfra:FacilityPart</td><td>BhFeatureOfInterest</td></tr><tr><td>C</td><td>RiskZone</td><td>nz:RiskZone</td><td>BhFeatureOfInterest</td></tr></tbody></table>

## 4.2. General considerations

### 4.2.1. Borehole Interoperability Experiment

Following the birth of the OGC GeoScience DWG in September 2017, an Interoperability Experiment about Borehole data was launched.

Starting in March 2018, during the Orleans OGC TC, the GeoScience DWG work on how connect several existing borehole definitions.

More details about this initiative can be found on the Borehole IE Github.

#### Engineering report

This document describes a conceptual model, logical model, and GML/XML encoding schema for the exchange of borehole related data and especially all the elements that are positioned along a borehole trajectory. In addition, this document provides GML/XML encoding instances documents for guidance

Link to the OGC engineering report: https://hal.science/hal-03943388/

#### Sampling Boreholes

Before one can provide data for various tests to be performed on boreholes, one must determine what spatial features must be defined to serve as features-of-interest for these tests. We sStart by differentiating between the Hole (the absence) and the Core in their entirety. Both the Hole and the Core can then be subdivided, either as Points or as Segments. Dedicated featureTypes have been created for all six of these variants, as illustrated in the diagram below.
<figure><img src="image_9.png" /><figcaption>Figure 8. SF_BoreholeClasses</figcaption></figure>

As linear referencing is a key function for the provision of borehole observation, it was then proposed to connect ISO19148 (linear referencing) and ISO 19156 (observations, measurements and samples).

### 4.2.2. Geometries in OGC

This page is about how geometries are currently handled by OGC standards. OGC Standards consider two- and three-dimensional (2D and 3D) geometries. All OGC feature (vector) geometries ultimately are based on the OGC Abstract Specification Topic 1 - Spatial Schema (published as ISO 19107:2019).

#### Simple Features (2D)

OGC's oldest and most-implemented Standard, Simple Features, describes how to define and encode 2D feature geometries. Simple Features representation is used in all other OGC and similar Standards for feature geometry, including the list below. Simple Features is also the native geometry for geospatial-enabled commercial and open source database systems.

#### GML (2D and 3D)

As written here, the Geography Markup Language (GML) from OGC is

an XML grammar for expressing geographical features. GML serves as a modeling language for geographic systems as well as an open interchange
format for geographic transactions on the Internet. GML is also an ISO standard (ISO 19136:2007).

## GeoJSON (2D)

Contrary to some belief, GeoJSON is not authored by OGC but by the IETF. One current limitation of GeoJSON is the fact that it is only handling one coordinate reference system (CRS): EPSG:4326. Yet the big interest of the internet for JSON based format makes it worth considering.

## OGC Features and Geometries JSON (2D and 3D)

The work-in-progress OGC Features and Geometries JSON is designed to be the successor of GeoJSON. It is designed such that it can be used in a way that is fully backwards-compatible with GeoJSON. It does this by leaving all fields and structures defined by GeoJSON in place, and only defining new functionality in new fields that do not conflict with existing properties.

OGC Features and Geometries JSON will:

* include the ability to use Coordinate Reference Systems (CRSs) other than WGS84

* follow the OGC Axis Order Policy,

* allow the use of non-Euclidean metrics, in particular ellipsoidal metrics,

* support solids and multi-solids as geometry types, and

* provide guidance on how to represent feature properties, e.g., including temporal properties.

The development of FG-JSON happens on: https://github.com/opengeospatial/ogc-feat-geo-json

## Geo3DML (3D)

In Geo3DML: A standard-based exchange format for 3D geological models, the China Geological Survey studied the topic of 3D space geomodels. They proposed extensions of OGC standards are proposed, especially for geometries.

## Voxels (3D)

Voxels (or volumetric cells) are a 3D gridded representation of a volume, with attributed values. Voxels can be expressed directly as modeled cubes in Standards such as CityGML or as datacubes represented by coverages or in formats such as HDF5 or Zarr, amongst others.

## The concept of gsml: MappedFeature in GeoSciML

The fact that models of the earth and their features can be represented in different ways is something well understood and managed in GeoSciML thanks to the concept of MappedFeature that is defined *this way*:

A MappedFeature is part of a geological interpretation. It provides a link between a notional feature (description package) and one spatial representation of it, or part of it (exposures, surface traces and intercepts,
etc.). The mapped features are the elements that compose a map, a cross-section, a borehole log, or any other representation. The mappingFrame identifies the domain being mapped by the geometries. For typical geological maps, the mapping frame is the surface of the earth (the 2.5D interface between the surface of the bedrock and whatever sits on it; atmosphere or overburden material for bedrock maps). It can also be abstract frames, such as the arbitrary plane that forms a mine level or a cross-section, the 3D volume enclosing an ore body or the line that approximate the path of a borehole.

### 4.2.3. The distinction between feature properties and observations.

#### Definitions

A video introduction by Kathi Schleidt of the observation concept can be found here: https://www.youtube.com/watch?v=bYDSgs2fKLk

It notably proposes an explanation of what is an observation vs a property of a feature. The picture below makes it clear.

<figure><img src="image_10.png" /><figcaption>Figure 9. Feature property and Observation</figcaption></figure>

**Feature property:** one object called the feature (here the smiley face) is identified and is associated to a property (here Expression = Happy)

**Observation:** a dedicated object called the observation is set. It is more exactly an act which itself have some properties that enable to define the context and also the result of the observation act (here that the Smily Face looks to be of a yellow color according to Kathy's experience).

#### Feature properties vs observations

Feature properties are a direct way to associate an information to an object. The association is “absolute” in the sense that it is always true, no matter when, who/what is involved in describing the object. For example, the name of a person, its date of birth.
On the contrary, the observation concept offer the capacity to contextualize an information that is provided. For example, the time, the location, the method, the observer: that is to say conditions in which the information was obtained and may have an important impact on the validity of the result.

For those reasons one can see that:

* feature properties perfectly fit domain where the knowledge of the objects are well mastered. This is typically the case in **industry** that propose to build from hand or machine made well known components.

* observation is very relevant in domain where the knowledge is incomplete, or when only a small part (either in terms of space or time) of an object is studied. This is typically the case in **science** where each information must be kept in its context before (possibly) deducting a more general law or rule.

## When to use one or the other in geotechnics

Information obtained through a process of observation, measurement, interpretation or even calculus fit the concept of observation and shall be exposed that way.

## How to associate observations to features?

A basic need for semanticized objects is to be able to associate them with information.

## Approach 1: (Direct) Feature properties, as in GeoSciML Lite
<figure><img src="image_11.png" /><figcaption>Figure 10. In this simplified version of GeoSciML, a direct association between the “ObservedProperty” and the “Result” is provided.</figcaption></figure>

Approach 2: Association of one ObservedProperty to a Measurement, as in GroundWaterML2
<figure><img src="image_12.png" /><figcaption>Figure 11. Here the gwUnitThickness of the GL_GeologicUnit is intended to be provided as a Measurement, following ISO19156.</figcaption></figure>

To realize this association, the “ObservedProperty” shall be associated to the identifier of a Measurement Object. A clean way to do that is to have the measurement exposed through an OGC API and use the link to it.

The picture below illustrates measurement with a link to a WFS service.
<figure><img src="image_13.png" /><figcaption>Figure 12. Extracted from https://www.youtube.com/watch?v=L1L2u3u35cY</figcaption></figure>

## Approach 3: Association to an OGC API

A drawback of the second approach is that one needs to have all the ObservedProperties described in the feature and to associate the results one by one.

A solution to avoid this constraint is to directly associate the feature to an "Observation Oriented API" that will list the available observations associated to the feature.

The following request to an [Introduction-to-SensorThingsAPI-data-model[OGC SensorThingsAPI]] enable to list the "DataStreams", that is to say collection of observations associated to the Object of interest (here a borehole or BhTrajectoryThing):

https://ogc-demo.k8s.ilt-dmz.iosb.fraunhofer.de/FROST-GeoTech/v1.1/BhTrajectoryThings(11)/Datastreams

This is the preferred approach for this IE.

# 4.3. ISO 19148 and ISO 19156

## 4.3.1. Introduction

For the data modelling on the GeoTech IE, in addition to the basic OGC geospatial standards, the following two standards where of core interest, strongly guiding the final data model.

### ISO 19148

Linear Referencing Systems enable the specification of positions along linear objects. The approach is based upon the Generalized Model for Linear Referencing[12] first standardized within ISO 19133:2005. This document extends that which was included in ISO 19133, both in functionality and explanation.

ISO 19109 supports features representing discrete objects with attributes with values which apply to the entire feature. ISO 19123 allows the attribute value to vary, depending upon the location within a feature, but does not support the assignment of attribute values to a single point or length along a linear feature. Linearly located events provide the mechanism for specifying attribution of linear objects when the attribute value varies along the length of a linear feature. A Linear
Referencing System is used to specify where along the linear object each attribute value applies.
The same mechanism can be used to specify where along a linear object another object is located,
such as guardrail or a traffic accident.

It is common practice to segment a linear object with linearly located events, based upon one or
more of its attributes. The resultant linear segments are attributed with just the attributes used in
the segmentation process, ensuring that the linear segments are homogeneous in value for these
segmenting attributes.

ISO 19156

The Observations, Measurements, and Samples standard (OMS), jointly prepared and published by the Open Geospatial Consortium and ISO/TC 211 as OGC Abstract Specification Topic 20 (OGC 20-082r4) and ISO 19156:2023, defines a conceptual schema for observations, for features involved in the observation process, and for features involved in sampling when making observations. Models support the exchange of information describing observation acts and their results, both within and between different scientific and technical communities.

Observations commonly involve sampling of an ultimate feature-of-interest. OMS defines a
common set of sample types according to their spatial, material (for ex situ observations), or
statistical nature. The Standard's schema includes relationships between sample features (sub-
sampling, derived samples). It also adds concepts that were deemed missing in the previous version
and provides additional clarification to the provided concepts and their relationships while keeping
the core data model mostly intact. In addition, a new fine-grained requirements class structure has
been created, enabling implementations to unambiguously declare the parts of the standard they
conform to.

The abstract data models described in OMS provide common concepts and logical structures for exchanging observational data and metadata between various information systems as well as for harmonized handling of such information from various heterogeneous sources. Technical implementation standards and profiles, on the other hand, provide concrete solutions tailored for storing, exchanging and processing OMS information in particular technical environments and use cases.

The work on revising existing OMS-related OGC Implementation Standards to fully comply with the OGC 20-082r4 requirements is in progress in OGC, including Sensor Things API and Timeseries Markup Language. Work is also underway for harmonization between the already closely related OMS and the W3C SSN/SOSA Standards. New OGC Implementation Standards are being pursued for OMS JSON encoding and OMS related dataset metadata led by the OGC OMS Standards Working Group.

The OMS family of Standards contribute to the FAIR (Findable, Accessible, Interoperable, Reusable) principles for various kinds of measurable information, including environmental monitoring as well as remote and in-situ sensing by providing a common conceptual framework for discovering, collecting, and analyzing related information from various sources and data providers.

Geotech concepts which might use ISO 19148 and ISO 19156

Those data models and the extensions designed for them are proposed in order to realize all the
concepts listed in [Book-A-organization-and-components], including:

* Observation

* [Sampling-and-Preparation]

* Borehole

* MaterialSample

### 4.3.2. Motivation

As described in the *Brief introduction to ISO 19148 and ISO 19156*,

ISO 19148 was designed in order to express locations along a linear object, and

ISO 19156 was designed in order to describe observations, measurements and samples.

The motivation to connect ISO 19148 and ISO 19156 is to have the capacity to describe observations, measurements and samples that are linear referenced. In geotechnics, one major use case for that is borehole data.

#### Methodology

In order to explain the approach toward integrating the concepts from Linear Referencing (ISO 19148) with parallel concepts from the Sampling part of Observations, Measurements and Samples (ISO 19156), start with an example provided with the Linear Referencing standard. When specifying a feature located along a linear feature, 19148 utilizes the FeatureEvent Class. This Event references the following.

* the linear feature under consideration, association role: linearElement

* information where along this linear feature (distance relative to the origin of the linear feature) the linearly referenced feature is located (this can be a point or interval; dataTypes AtLocation and FromToLocation provided for this information). Association role: location

* the linearly referenced feature, located along the linear feature. Association role: locatedFeature.

In the example provided with 19148, a wildlife fence is located at a specific position along a road (from meter 0 to meter 5), leading to the following UML:
<figure><img src="image_14.png" /><figcaption>Figure 13. Feature event example</figcaption></figure>

In a first step, the same structure was used, but the classes from the example were replaced by examples relating to boreholes and sampling a segment of this borehole. In addition, where relevant, Interfaces from the OMS model were added, in order to show the alignment between the interfaces from Linear Referencing with those from OMS. Class replacements were as follows:

* FT Road: `BH_Trajectory`

* FT WildlifeFence: `BH_Segment`
This brings us to the following UML:

<figure><img src="image_15.png" /><figcaption>Figure 14. Linear Sampling</figcaption></figure>

In this diagram, the parallel between the linear referencing FeatureEvent and the OMS Sampling become apparent, as well as the fact that the linear referencing locatedFeature corresponds with the OMS Sample. In addition, the location information is related to the OMS SamplingProcedure.

However, when dealing with boreholes, it is common to provide information on the borehole collar, to indicate the start of the borehole (as well as to provide additional information on the borehole). The linear referencing model foresees the Referent Interface to provide the origin of the linear feature. Integrating a BH_Collar featureType into the model above leads us to the following final level of the conceptual linear borehole model:
<figure><img src="image_16.png" /><figcaption>Figure 15. Linear Sampling Reference</figcaption></figure>

### 4.3.3. Conceptual Borehole Model

The core conceptual model for boreholes consists of the following featureTypes.

* BH_Collar: Information on the location of the borehole collar, together with relevant attributes.

* BH_Trajectory: The trajectory of the borehole. Encoding of the Geometry TBD, as unclear if we use a 3D Linestring or local polar coordinates.

* BH_SamplingFeatureEvent: An act applying a SamplingProcedure to create or transform one or more Sample(s). Information on how and where the Sample of the borehole under investigation (Point or Segment) has been sampled from this borehole.

* BH_FoI (Sample) Types: An object that is representative of a concept, real-world object or phenomenon.

* BH_Hole: A featureType representing the entire Hole of the borehole.
* BH_HolePoint: A featureType representing a point along a borehole Hole, as indicated by the attribute atPosition.

* BH_HoleSegment: A featureType representing a segment of a borehole Hole, as indicated by the attributes fromPosition and toPosition.

* BH_Core: A featureType representing the entire Core of the borehole.

* BH_CorePoint: A featureType representing a point along a borehole Core, as indicated by the attribute atPosition.

* BH_CoreSegment: A featureType representing a segment of a borehole Core, as indicated by the attributes fromPosition and toPosition.

Note 1: Position values in the BH_FoIs are relative to the BH_Trajectory

Note 2: Point and Segment FoIs are sampled from the BH_Trajectory, not the entire Hole or Core. This modeling decision was reached due to technical constraints posed by STA. In order to maintain the link between Point and Segment FoIs and their entire Hole or Core feature, the sampledFeature association will be used.

In addition, the diagram below still shows the dataTypes providing the EventLocation, namely AtLocation and FromToLocation. However, the relevant attributes have already been shifted to the BH_Point and BH_Segment featureTypes respectively, valid due to 1:1 associations between these types.
<figure><img src="image_17.png" /><figcaption>Figure 16. Borehole Sampling</figcaption></figure>

Conceptual Borehole Model with Interfaces

In addition, we provide the same image including the relevant interfaces from the Linear
Referencing and OMS Standards.
<figure><img src="image_18.png" /><figcaption>Figure 17. Borehole Sampling Interfaces</figcaption></figure>

Conceptual Borehole Model with all Sampling Classes

In order to provide detailed information on how the Samples have been created, as well as any additional processing steps performed on these samples, the additional featureTypes from the OMS Sampling model have also been added. The following classes have been added to the diagram below.

* BH_Sampler: a device or entity (including humans) that is used by, or implements, a SamplingProcedure to create or transform one or more Sample(s).

* BH_SamplingProcedure: description of steps used to create or transform a Sample.

* BH PréparationStep: an individual step pertaining to a PreparationProcedure.

* BH PréparationProcedure: description of preparation steps performed on a Sample that is being observed.
<figure><img src="image_19.png" /><figcaption>Figure 18. Borehole Sampling Complete</figcaption></figure>

## 4.4. SensorThings API data model

### 4.4.1. Introduction to OGC SensorThings API

The OGC SensorThings API (STA) was originally designed to be an API for exchanging observational data in the IoT domain, but it quickly shown itself to be a full successor to the OGC Sensor Observation Service. The SensorThings API in short:

* A standard for exchanging sensor data and metadata

* Historic data & current data

* RESTful + JSON Encoded, with a powerful querying mechanism (based on OASIS OData)

* Supporting ISO MQTT messaging

* Easy to use & understandable: Discoverable with just a web browser

Here is a diagram showing the different classes from OGC SensorThings API Part 1: Sensing Version
<figure><img src="image_20.png" /><figcaption>Figure 19. SensorThings API Part 1</figcaption></figure>

For those who are familiar with ISO 19156 (aka OGC OMS), one will find those data models have a lot in common.

The main class to consider is the Observation that provides the result that was obtained at a specific date, location, following a particular procedure. The ObservedProperty, Sensor, Thing and FeatureOfInterest enable the contextualization of those parameters.

The main difference with OMS relies in the fact that STA introduces the Datastream concept as a way to group observations that "come together".

This is very common with repeated measurements like time series, or measurements made along a trajectory. The Datastream enables grouping those observations and avoids repeating parameters that remain unchanged like the Sensor or Observed Property.

This concept is explained further in this video: https://www.youtube.com/watch?v=bYDSgs2fKLk

Further documentation of the OGC SensorThings API:

* The specification of version 1.1: https://docs.ogc.org/is/18-088/18-088.html

* The GitHub page: https://github.com/opengeospatial/sensorthings

* Tutorials and examples made for INSPIRE: https://datacoveeu.github.io/API4INSPIRE/sensorthingsapi/1_Home.html
GeotechIE proposes to reuse and extend this data model to accommodate the provision of borehole
data. See STA Borehole Model

4.4.2. STA Borehole Model

Based on the Conceptual Borehole Model, a physical STA-based model has been derived. In the diagram below, you see both the core STA data model as well as the various extensions proposed for the GeoTech IE.

<figure><img src="image_21.png" /><figcaption>Figure 20. Borehole STA</figcaption></figure>

In order to understand how this physical model has been created from the Conceptual Borehole
Model, the following diagram sets the STA classes into their conceptual context, indicating which
STA classes realize which classes from the Conceptual Borehole Model.
<figure><img src="image_22.png" /><figcaption>Figure 21. Borehole STA Complete</figcaption></figure>

## 4.5. GeoSciML

### 4.5.1. Introduction to GeoSciML

From the CGI-IUGS website:

**GeoSciML** is an XML-based data transfer standard for the exchange of digital geoscientific information. It accommodates the representation and description of features typically found on geological maps, as well as being extensible to other geoscience data such as drilling, sampling, and analytical data. **GeoSciML** provides a standard data structure for a suite of common geologic features (eg, geologic units, structures, earth materials) and artifacts of geological investigations (e.g., boreholes, specimens, measurements). Supporting objects such as the geologic timescale and vocabularies are also provided as linked resources, so that they can be used
as classifiers for the primary objects in the GeoSciML standard.

The latest version of the specifications of that joint CGI-IUGS and OGC standard can be found here:
https://docs.ogc.org/is/16-008/16-008.html

### 4.5.2. Existing concepts proposed for reuse and extension for geotechnics

* gsml:GeologicUnit

* gsml:ShearDisplacementStructure

* gsml:Fold

* gsml:Contact

* gsml:Joint

### 4.5.3. Concepts proposed for addition to geotechnics?

* gsml:GeotechUnit

### 4.5.4. GeologicUnit according to GeoSciML

From GeoSciML v4.1:

Conceptually, a GeologicUnit may represent a body of material in the Earth whose complete and precise extent is inferred to exist (e.g., North American Data Model GeologicUnit, Stratigraphic unit in the sense of NACSN, or International Stratigraphic Code), or a classifier used to characterize parts of the Earth (e.g. lithologic map unit like 'granitic rock' or 'alluvial deposit', surficial units like 'till' or 'old alluvium'). It includes both formal units (i.e. formally adopted and named in an official lexicon) and informal units (i.e. named but not promoted to a lexicon) and unnamed units (i.e., recognizable, described and delineable in the field but not otherwise formalised). In simpler terms, a geologic unit is a package of earth material (generally rock).

#### Geotech concept that can use gsml:GeologicUnit

gsml:GeologicUnit is identified to realize the geotech concept called GeologicUnit.

More specifically, gsml:GeologicUnit definition is large and enable to address different kind of units.

In geotechnics, when speaking about a geologic unit, the most common understanding is "Lithostratigraphic Unit".
### 4.5.5. ShearDisplacementStructure according to GeoSciML

From GeoSciML v4.1:

A **shear displacement structure** includes all brittle to ductile style structures along which displacement has occurred, from a simple, single 'planar' brittle or ductile surface to a fault system comprised of tens of strands of both brittle and ductile nature. This structure may have some significant thickness (a deformation zone) and have an associated body of deformed rock that may be considered a deformation unit (which geologicUnitType is 'DeformationUnit') which can be associated to the **ShearDisplacementStructure** using GeologicFeatureRelation from the GeoSciML Extension package (8.5.1.2).

**Geotech concept that can use gsml:ShearDisplacementStructure**

gsml:ShearDisplacementStructure is identified to realize the geotech concept called Fault.

### 4.5.6. Fold according to GeoSciML

From GeoSciML v4.1:

A fold is formed by one or more systematically curved layers, surfaces, or lines in a rock body. A fold denotes a structure formed by the deformation of a geologic structure, such as a contact which the original undeformed geometry is presumed, to form a structure that may be described by the translation of an abstract line (the fold axis) parallel to itself along some curvilinear path (the fold profile). Folds have a hinge zone (zone of maximum curvature along the surface) and limbs (parts of the deformed surface not in the hinge zone). Folds are described by an axial surface, hinge line, profile geometry, the solid angle between the limbs, and the relationships between adjacent folded surfaces if the folded structure is a Layering fabric.

**Geotech concept that can use gsml:Fold**

gsml:Fold is identified to realize the geotech concept called Fold.

### 4.5.7. Contact according to GeoSciML

From GeoSciML v4.1:

A **contact** is a general concept representing any kind of surface separating
two geologic units, including primary boundaries such as depositional contacts, all kinds of unconformities, intrusive contacts, and gradational contacts, as well as faults that separate geologic units.

### Geotech concept that can use gsml:Contact

gsml:Contact is identified to realize the geotech concept called Contact.

## 4.5.8. Adding GeotechUnit

The proposal is to have gsml:GeotechUnit defined as a specialization of gsml:GeologicUnit.

In GeoSciML, the concept of Geologic Unit is defined as "a package of earth material" (see: GeologicUnit). To offer some variations of the Geologic Unit concept, CGI introduced Geologic Unit types.

The proposal is then to add a Geologic Unit type entitled GeotechUnit which would follow this definition:

> A geologic unit defined by its geotechnical properties

### Geotech concept that can use gsml:GeotechUnit

gsml:GeotechUnit is identified to realize the geotech concept called GeotechUnit.

### How representations / geometries should be handled for gsml:GeotechUnit?

As gsml:GeotechUnit is proposed as a specialization of gsml:GeologicUnit which it itself a specialization of a GeologicFeature it inherits its capacity to be associated to (multiple) gsml:MappedFeature which are intended to each one to be possible representation of the concept.

### Geotechnical properties

A GeotechUnit being a GeologicUnit, it inherits its properties.

## 4.5.9. Joint

The gsml:Joint concept is not mentioned in the GeosciML v4.1 specifications but is clearly identified in the UML model as part of the Geologic Structure Details.
<figure><img src="image_23.png" /><figcaption>Figure 22. Geologic Structure (including Joint)</figcaption></figure>

A gsml:Joint is defined as a:

> Fracture across which there is no displacement at the scale of interest.

gsml:Joint is as a specialization of a gsml:Fracture defined which is defined as:

> Fractures are cracks in the earth surface. If there is no displacement it is a joint. If there is displacement and you are in the brittle zone it is a fault. In the ductile zone, a fracture with displacement with fracture is called a shear.

## Geotech concept that can use gsml:Joint

gsml:Joint is identified to realize the geotech concept called DiscreteDiscontinuity.

## How representations / geometries should be handled for gsml:Joint?

As gsml:DiscreteDiscontinuity is proposed as a specialization of gsml:GeologicStructure which it itself a specialization of a GeologicFeature it inherits its capacity to be associated to (multiple) gsml:MappedFeature where each one are intended to be possible representation of the concept
## Geotechnical properties

A GeotechUnit being a GeologicUnit, it inherits of its properties.

# 4.6. GroundWaterML2

## 4.6.1. Introduction to GroundWaterML2

From the dedicated page on the OGC Website:

> This standard describes a conceptual and logical model for the exchange of groundwater data, as well as a GML/XML encoding with examples.

The latest version of the specifications of that OGC standard can be found here: https://docs.ogc.org/is/19-013/19-013.html

Existing concepts proposed for reuse and extension for geotechnics

* HydroGeoUnit

* FluidBody

* FluidBodysurface

* HydroGeoVoid

## 4.6.2. HydroGeoUnit according to GroundWaterML2

From GroundwaterML2:

> Any soil or rock unit or zone that by virtue of its hydraulic properties has a distinct influence on the storage or movement of groundwater (after ANS, 1980).

Geotech concept that can use gwml2:HydroGeoUnit

gwml2:HydroGeotUnit is identified to realize the geotech concept called HydrogeoUnit.

## 4.6.3. FluidBody according to GroundWaterML2

From GroundwaterML2:

> A distinct body of some fluid (liquid, gas) that fills the voids of a container such as an aquifer, system of aquifers, water well, etc. In hydrogeology this body is usually constituted by groundwater, but the model allows for other types of fillers e.g., petroleum.