bluuebunny/crossref_metadata_2025 huggingface dataset:
A plane slide that occurred during construction of a national expressway in Chongqing, SW China
Authors: Yue Z.Q. , Lee C.F.
Published: November 2007

This paper presents a case study of a major landslide that occurred during the construction of a national expressway in Chongqing, southwestern China. The landslide was a typical plane failure associated with steep cutting in weathered mudstone and sandstone. The weathered mudstone block slipped down along the bedding interface of the mudstone and sandstone and formed an open gap that measured some 6 to 8 m high, by 2 to 7 m wide and 53 m long in the hillside slope. This study referred that the landslide was caused by the combined effect of the following factors: (a) an unsupported high and steep cutting in weathered mudstone; (b) an exposed bedding interface between the incompetent weathered mudstone and the competent sandstone that daylights within the cut slope; (c) the mudstone and sandstone bedding interface as a pre-existing folding tectonic shear plane of low shear strength; and (d) the possible presence of a ground water table in the weathered mudstone perched on the relative impervious sandstone bedding surface. The case study highlights the importance of engineering geologicalmapping during and immediately after the formation of a new cut slope. It also emphasises the importance of identification of the pre-existing tectonic shear planes along the mudstone and sandstone bedding interfaces in similar geological terrain.
Sample preparation effects on the compaction properties of Swedish fine-grained tills
Authors: Lindh Per , Winter M.G.
Published: November 2007

Fine-grained tills are a dominant feature of the drift geology of Sweden. Until recently their use in earthworks applications has been limited due to the plentiful supply of naturally occurring gravel and crushed rock, and their high sensitivity to moisture content change which often leads to the view that fine-grained tills are problem soils. Environmental and economic factors are, however, leading to pressure to increase the use of site-won materials, including fine-grained tills, in earthworks applications. This paper sets out the case for the increased use of fine-grained tills in such applications and examines the Moisture Condition Value test, for the determination of potential soil acceptability for earthworks, in the context of standards developed over 20 years in Britain and the emerging practice in Sweden. One of the key differences between Swedish practice and the approach followed in the BritishStandard is in terms of the sample preparation method employed. In Britain samples are air-dried prior to wetting to a range of moisture contents and testing while in Sweden an initially wet sample is selectively air-dried to achieve the desired range of moisture contents. The results of a detailed laboratory testing programme to investigate the influence of these sample preparation methods on the test results are presented. It is concluded that the Swedish method of selective air-drying is suitable for use in areas of high precipitation and associated high natural moisture contents. However, in areas wherenatural moisture contents are not consistently high the British Standard method is preferred. It is important to recognize that the sample preparation method employed will influence the test results and that the methods are not interchangeable. It is further found that, for the limited range of soils tested, there is no appreciable difference between the air-drying employed in the British Standard and oven-drying. However, it is recognized that further research is required in this area, not least on British soils.
Characterization of LNAPL in fractured rock
Authors: Hardisty Paul E. , Wheater Howard S. , Birks David , Dottridge Jane
Published: November 2007

Behaviour of light non-aqueous phase liquids (LNAPLs) within a fractured rock mass is a function of the properties of the immiscible fluid, the fracture network, rock matrix properties, and the groundwater regime. LNAPL behaves differently in rock with open fractures than it does in porous media. Relatively small volumes of LNAPL within vertical or subvertical fractures can produce significant LNAPLpressure heads, resulting in LNAPL penetration into the saturated zone. Penetration can be significantly deeper than predicted by porous medium models. Groundwater surface fluctuations can cause lateral LNAPL migration, even up-gradient to natural gradients. Characterization of LNAPL-contaminated fractured rock masses must take into account these fundamental differences in behaviour. Site investigation should focus on determination of fracture network and rock matrix properties, understanding of groundwater surface fluctuation dynamics, and consideration of spatial LNAPL distribution. A combination of techniques, many not used in porous medium investigations, but can used to develop a detailed conceptual model. These include coring, angled holes, digital borehole imaging, and fracture casting for aperturedetermination. The data provide information on LNAPL occurrence and behaviour, allow LNAPL spill volume to be estimated, indicate future movement, and ultimately allow for more effective and economic remedial decision making.
The effect of weathering on Alpine rock instability
Authors: Jaboyedoff M. , Baillifard F. , Bardou E. , Girod F.
Published: November 2007

Weathering affects joint or fault gougematerial in the Swiss Alps, leading to the formation of smectite, which changes the mechanical properties of fault gouge and degrades slope performance. Analysis of recent rockslides in gneissic rocks in Switzerland indicates that accelerations of movements are linked to precipitation, without the development of excess pore water pressure. Processes such as weathering and crushing induce soil-like behaviour of the infilling material and explain rockslide movements induced by water seepage in both fault and joint gouges.
Applied geological mapping for planning and development: an example from Wigan, UK
Authors: Forster A. , Lawrence D.J.D. , Highley D.E. , Cheney C.S. , Arrick A.
Published: November 2007

The applied geological mapping study of the Wigan Metropolitan Borough was completed in October 1995 by the British Geological Survey (BGS) in association with the planning consultants Roger Tym & Partners. The aim of the project was to provide a geoscience basis for planning and development decisions. The users of the study were seen primarily as planners and developers but also engineers, conservationists and others. The important common factor was that the users need not have geological training. The study represented the state-of-the-art in the UK in terms of the transfer of geological information to nongeologists. Geoscience data were compiled as a series of nine thematic maps and a technical report in which the geology of the area, and its modification by human activities, were described. The engineering geology map is significant in that it uses the stripe method of showing subsurface information, a method rarely used in the UK since its first use by Dearman in the North East of England. The key geological factors relevant to planning and development were identified by the project team during discussions with local planners and developers. They were summarized on a map and described in a report that indicated how and where geology might significantly affect development. The successful outcome of this study required a multidisciplinary team approach and good communication between team members.
Nitrate in groundwater: a water company perspective
Authors: Beeson Sarah , Cook Mike C.
Published: November 2007

More than 100 groundwater sources operated by Anglian Water Services are vulnerable to diffuse and point pollution, and 33 of these sources have nitrate concentrations in excess of 50 mg l
−1
as NO
3
. Most time series nitrate data ‘recess’ to a long-term rising baseline, upon which seasonal variations and/or data scatter are superimposed. Investigations at boreholes abstracting from the Chalk aquifer show that concentrations decrease with depth below the water table and with time after pump start-up. Abstraction rates do not affect concentrations but the combination of boreholes in use does. A reliable and robust semi-quantitative method for predicting future nitrate concentrations has been developed. Use of this method has allowed a rigorous definition of capital investment requirements under the AMP4 process to maintain compliance with drinking water standards. The method has been used to predict short-term nitrate concentrations for a variety of recharge scenarios.
Integrated seismic investigations across the Mersey Estuary, Halton District, UK
Authors: Lenham J.W. , McDonald R. , Miller S. , Reynolds J.M.
Published: November 2007

Acombined terrestrial and marine seismic investigation has been undertaken of the Inner Mersey Estuary, Halton District, UK, prior to construction of a major new river crossing. Much of the site lies on inter-tidal sand and mud bars accessible only for restricted periods and is unsuited to prolonged physical investigations using heavy plant. The investigation included high-resolution seismic refraction and reflection surveying on the salt marsh and inter-tidal regions, plus sub-bottom profiler investigation of the main river channel. Strategically located boreholes followed the geophysical work. Results show that the current configuration of the Inner Mersey Estuary is largely unrelated to the underlying bedrock geometry. In the area surveyed, the River Mersey is located on the southern flank of a buried elongate depression in the bedrock surface whose approximate position has been investigated previously between Ditton Marsh and Warrington through the interpretation of borehole records. The results also demonstrate a clear increase in compressional (
P
) wave seismic velocity of the Triassic sandstone with age, allowing the possible detection of an important fault. This paper highlights the potential for saving project capital through a properly designed geophysical site investigation prior to the commencement of major civil engineering projects.
Groundwater occurrence and the distribution of wellsand springs in Precambrian and Palaeozoic rocks,NW Anglesey
Authors: Robins N.S. , McKenzie A.A.
Published: November 2007

Adataset of well and spring locations in NW Anglesey with accompanying geological observations was recently discovered at the British Geological Survey. The data are likely to have been recorded as part of an environmental survey in the late 1960s or early 1970s. The area comprises Palaeozoic and Precambrian rocks partly covered by moderately permeable till. The bedrock forms a shallow fractured aquifer, which offers individual well and spring discharges up to 2 l s
−1
. The newly discovered data provide an indicator of the hydraulic characteristics of each bedrock type such that the Holyhead Quartzite Formation offers the least favourable hydraulic conditions, whereas a small area of Silurian (Llandovery) strata at Parys Mountain offers the most favourable hydraulic characteristics. The occurrence of discontinuities caused by dyke intrusion and metamorphic foliation make some Precambrian strata better disposed to successful well digging than others. Base flow index data indicate that storativity is greatest in the Precambrian and the Carboniferous Limestone Formation. Groundwater chemistry reflects shallow, short groundwater flowpaths.
A framework for rapidly assessing the pollutant retardation capacity of aquifers and sediments
Authors: Smith J.W.N. , Lerner D.N.
Published: November 2007

Pollutants are subject to a variety of processes that attenuate their transport within aquifers and sediments. Natural attenuation processes are commonly considered during the assessment and management of risks associated with contaminated land and groundwater. A framework has been developed that allows rapid assessment of the potential for aquifers or river-bed sediments to retard dissolved pollutants. Retardation by sorption to organic carbon, cation exchange and acid buffering are considered for a range of common and relevant groundwater pollutants. Based on simulated pollutant behaviour, thresholds for high, moderate and low attenuation capacity have been generated. The methods are described so that users can adjust the boundaries (of the attenuation classifications) to best suit the needs of other assessment decisions. The framework relies solely on measurements of the fraction of organic carbon, cation exchange capacity and total inorganic carbon content in an aquifer or sediment. It can be undertaken during the initial evaluation of a hydrogeological risk assessment or monitored natural attenuation evaluation, and will help assessors to prioritize subsequent site-specific investigations on pollutant attenuation. The framework has been tested against field data and is shown to usefully differentiate British strata, based on the geochemical properties that control pollutant retardation.
Effect of a Clay Cap on oxidation of Pyrite withinMine Spoil
Authors: Gandy C.J. , Younger P.L.
Published: November 2007

Polluted discharges from perched groundwater systems in mine spoil heaps are a significant cause of water pollution in many parts of the world. Oxidative weathering and dissolution of sulphide minerals, particularly pyrite, which is widespread within Coal Measures strata, frequently results in surface water discharges rich in iron, sulphate, aluminium and acidity. Reducing the availability of oxygen to mineral surfaces should limit the amount of oxidation taking place and, therefore, reduce the concentrationsof contaminants in percolating waters. A pollutant-generating portion of a spoil heap in County Durham, UK, was covered with a clay cap in February 1998, and subsequent monitoring has shown a significant reduction in the concentrations of contaminants in the water discharging from the spoil heap to a nearby constructed wetland treatment system. This allows the wetland to receive better quality water, thereby extending its future life and making it even more sustainable.
Landsliding in London Clay coastal cliffs
Authors: Dixon N. , Bromhead E. N.
Published: November 2007

Factors controlling rotational landsliding in the unprotected London Clay coastal cliffs atWarden Point, Isle of Sheppey, Kent, aredescribed. Surveys of the landslides have been carried out at regular intervals since1971, and these are supported by an extensive subsurface investigation that included the installation of 56 piezometers. These studies have resulted in an understanding of the pore water pressures in the cliffs, including the role of undrained unloading resulting from slope formation, and pore pressures within the landslide mass ‘carried down’ the slope. The zone of depressed pore pressures is carried inland with the slope as the coastline retreats. Factors controlling the shear strength mobilized during first-time slides, and rates of movement, include geological control on the position of the slip surface and reduction in shear strength to close to the residual value along the basal section of the slip surface. This strength reduction results from stress relief controlled pre-failure deformations. A simple model is proposed to allow calculation of pore water pressures associated with the degrading slide mass. These have enabled back-analyses to be carried out which extend the residual shear strength envelope for London Clay to high effective normal stress levels, and explain the rate of re-activated slide movements.
Engineering geological constraints for highways schemes in Ireland: N6 Kinnegad to Athlone dual carriageway case study
Authors: Phipps P.J.
Published: November 2007

This paper describes the methodology that was developed for a series of engineering geological constraints studies for highway schemes inIreland. These comprised the synthesis of findings from two main study elements; an initial desk study review of published information sources and the results of a terrain systems mapping study for areas up to 600 km
2
. The main requirement was to identify, classify and delineate those potential geomorphological andengineering geological constraints to possible highway route corridors.

A case study for the N6 Kinnegad to Athlone Dual Carriageway is presented which includes the published sources that were reviewed and information obtained, and the initial terrain systems mapping exercise that was undertaken. Fourteen different terrain units were identified and their distribution was presented on 1:50 000 scale drawings. Characteristic physiography, materials, resources and constraints associated with the terrain units were presented in summary tables. The relative constraints to highway design and construction were also presented on a series of 1:50 000 scale derivative drawings. Four route corridors that were considered the most viable from understanding of the engineering geological constraints and other factors including; archaeology,environment, and traffic were developed and formedthe basis for more targeted desk studies and fieldassessment, and the design of a preliminary ground investigation.
Geochemical modelling of fluoride concentration changes during Aquifer Storage and Recovery (ASR) in the Chalk aquifer in Wessex, England
Authors: Gaus I. , Shand P. , Gale I.N. , Williams A.T. , Eastwood J.C.
Published: November 2007

During ASR-cycle testing at a site in the confined Chalk near Lytchett Minster in Dorset, the high concentration of fluoride in the recovered water posed severe limitations on the success of the scheme. Based on physical modelling, the dual porosity character of the Chalk combined with high fluoride concentrations in the native water were identified as the key factors controlling the measured concentrations. However, mixing of water between the matrix pores and fractures was not sufficient to explain the fluoride concentration and it was concluded that there was an additional release of fluoride from aquifer interaction. This led to an additional increase in the fluoride concentration in the recovered water.

In order to investigate this hypothesis, a geochemical model incorporating reactions between the injected water, the native groundwater and the aquifer minerals was developed. The geochemical model PHREEQC-2 was set up so that it was capable of modelling ASR-cycles (including radial flow and diffusive mixing as a consequence of dual porosity). The physical aspects of the model were calibrated using a 3-D dual porosity transport model (SWIFT). Different geochemical processes (e.g. limited mineral availability, reaction kinetics) causing fluoride concentrations above those expected from dual porosity mixing were investigated. Comparing the modelled results with the observations from the test site suggested that slow dissolution of fluoride minerals (fluorite) was likely to be responsible for the additional increase in fluoride concentration in the recovered water.
Binder microstructure in lime mortars: implications for the interpretation of analysis results
Authors: Leslie Alick B. , Hughes John J.
Published: November 2007

Many historic mortars are composed of a silicate aggregate and a lime-based (calcitic) binder. Thin section examination suggests that binder structure and composition are complex and that binder quantity can vary significantly during the lifetime of a mortar.

Lime mortar analysis for conservation purposes commonly involves the quantification of binder: aggregate ratio by weight. Many such analyses of historic mortars have generated results suggesting compositions of 1 part lime binder: 1 part aggregate, in contrast to the 1: 3 ratio commonly specified in current building work.

The high binder content can, in part, be attributed to the presence of unmixed binder. Fragments of lime that have not been fully mixed with the aggregate do not, therefore, play the part of a binder during set. There is also evidence for dissolution and re-precipitation of binder in mortars, leading to changes to binder morphology as well as net gains or losses in binder content.

The presence of both lime inclusions and dissolution / re-precipitation textures within a mortar has implications for any mortar analysis method which relates the quantity of calcium carbonate to original binder content. Examination of a mortar, preferably using a petrological microscope, is essential if any meaningful quantitative data are to be generated.
Origin and mineralogy of African red clays and Keuper Marl
Authors: Dumbleton Michael John
Published: November 2007

African red clays and Keuper Marl are materials of contrasting origin and mineralogical composition. The red clays are residual soils produced by weathering of rocks at the land surface under relatively high temperature and rainfall and good drainage. Bases and silica are leached, leaving the soil rich in iron and aluminium. In Kenya the clay minerals and iron oxide occur respectively as metahalloysite and hematite under relatively dry conditions, and as hydrated halloysite and goethite under moister conditions. The plasticity of the clay minerals is modified by the iron oxide. Black montmorillonitic clays, rich in bases and silica, occur in association with the red clays but on lower ground.

The Keuper Marl is the product of weathering of higher land, which accumulated to a great thickness in a wide basin. Conditions of internal drainage led to enrichment of bases and silica. Calcium and magnesium are present as calcite and dolomite, and silica is present as quartz. All the clay minerals found were rich in magnesium and silica. Illite and chlorite were universal, and much of the chlorite was of the swelling type. In addition, sepiolite and palygorskite commonly occurred. Quantitative x-ray analyses showed up to 90 per cent of clay minerals, but particle-size analyses showed a much smaller proportion of clay-sized minerals, due to particle aggregation or to the occurrence of unusually large clay mineral particles.
Design and construction of a large cavity deep in the coal measures
Authors: Early Kenneth Reginald , Skipp Bryan Openshaw , Ferrier Robert
Published: November 2007

A large underground junction was to be constructed 2750 ft deep in the new Monkton Hall Colliery in Midlothian, Scotland. The junction was to house a bunker conveyor and stringent stability requirements were called for. The local geological condition was not favourable. The geological approach to the design is discussed. The design involved shaping and an intensive rock bolting programme. Support and construction methods are given and performance is described, including results of some photoelastic stress measurements.
A study of the mechanism governing the polishing of stone in road surfaces
Authors: Maclean Donald John
Published: November 2007

1. Introduction

O
ne
of the more important aspects of the work of the Road Research Laboratory is to develop better materials for surfacing roads. By 'better materials' is meant materials having greater resistance to cracking and deformation, greater durability against the effects of weather and greater ability to maintain an even and non-skid surface for traffic.

The surfacing materials in common use are concrete, asphalt and bituminous macadams; these consist of a mixture of mineral aggregates bound together with either Portland cement, bitumen or tar. The Laboratory is therefore concerned with obtaining an understanding of the properties of crushed rock and gravel aggregates that influence the behaviour of these surfacing materials.

This paper describes briefly the research into one important requirement of aggregates used in bituminous road surfacings. This requirement is that the exposed aggregate should not become polished by the action of traffic, since the degree of slipperiness of many types of bituminous surfacing is directly related to the extent to which the aggregate becomes polished.

2. Laboratory test

The first step was to develop a laboratory apparatus to determine how the polishing occurred. The aim was to reproduce as closely as possible the conditions of wear to which stone is subjected in the road surface. Thus, the apparatus (Pl. 1
a
) comprises a pneumatic-tyred wheel which rotates in contact with another wheel on the flat periphery of which are mounted small specimens of ⅜-in sized chipping bedded in a cement mortar (Pl. 1
b
). The wheel carrying the specimens is
Observations on small-scale structural discontinuities in the London Clay and their relationship to regional geology
Authors: Fookes Peter George , Parrish David Gordon
Published: November 2007

The London Clay is well known as an engineering material and it is probably the most publicized example of a stiff fissured clay. Recently, growing interest has been shown in the small-scale structural discontinuities of this clay and their effects on the engineering behaviour of the material. The paper deals with observations of small discontinuities (or fissures) at sites in the London and Hampshire Basins. Orientation data from the various sites are plotted and analysed in the form of stereographic projections. The size and form of the discontinuity surfaces are considered and their distribution related to orientation and possible modes of origin. Both orientation and surface forms of discontinuities are related to the regional structure of the clay and adjacent sediments, and it is tentatively concluded that the general trends of discontinuity patterns in local areas, the local regional structure, and geological history can be correlated.
Saline ground-waters in the Carboniferous Rocks of the English East Midlands in relation to the geology
Authors: Downing Richard Allen , Howitt Frank
Published: November 2007

The Carboniferous system in the East Midlands is comprised of a limestone-shale series or a massive limestone (the Carboniferous Limestone) overlain by a cyclic sequence of sandstones, mudstones, seat-earths and coals (the Millstone Grit and Coal Measures). The geology is described briefly and modifications are made to correlations of the Millstone Grit and Lower Coal Measures in the light of recent studies of information obtained by deep drilling for oil.

Most of the Carboniferous ground-waters discussed are saline with total concentrations ranging up to 246 000 mg/1. The concentration in all formations increases from the Eakring-Kelham Hills area towards Gainsborough, that is from SW to NE, and the variation in ionic content associated with this increase is discussed.

The ground-waters are believed to have originated from the diagenesis of Carboniferous marine and brackish waters and possibly some Permian marine waters. They have probably been concentrated by argillaceous beds acting as semi-permeable membranes and it is suggested that the increase in the Ca/Cl and Mg/Cl ratios as the total ionic concentration increases is due to the selective concentration of calcium and magnesium ions by argillaceous beds. In the south-west and south of the East Midlands the saline water has been diluted, probably by meteoric water moving through the aquifers from the outcrop areas and discharging into Permo-Triassic rocks, where these overlie Carboniferous aquifers at depth in the south-east of the region.
Foundations of multi-storey blocks on the Coal Measures with special reference to old mine workings
Authors: Price David George , Malkin Alexander Bernard , Knill John Lawrence
Published: November 2007

The rapid growth in the rate of construction of multi-storey blocks has been an important feature of the building industry over the past fifteen years. Much of this construction has occurred in areas underlain by the cyclothemic rocks of the Coal Measures. The aniso-tropic properties of this sequence lead to rapid horizontal and vertical variations in foundation conditions, which must be assessed in selecting the type and depth of foundation and the allowable bearing pressure. Special problems occur in areas which have been undermined by shallow mineral workings. Such sites require special investigations, careful evaluation of the site conditions and the design of appropriate foundations. The desirable approach in many instances is to plan developments on a large scale so that the greatest economic advantage may be taken of the best site conditions.

1. Introduction

During the past fifteen years there has been a rapid increase in the rate of construction and size of multi-storey blocks for dwellings and commercial development. Information on the total numbers of such blocks constructed in the United Kingdom per year is not conveniently published but is probably of the order of four to six hundred. Of this number, possibly one-third are constructed annually in areas underlain by Coal Measure rocks. This represents a national investment of about £70 million per year; the importance of the Coal Measures as a foundation is, therefore, underlined. This trend in building development reflects the increasing scarcity and cost of urban building land, coupled with the desire to confine
The stability of natural slopes in south-east England as affected by periglacial activity
Authors: Weeks Alan George
Published: November 2007

Details are given of trial pits which have been excavated during site investigations carried out in Kent and Oxfordshire over the past two and a half years. Slip surfaces have been found to a depth of 15 ft below the existing ground-level on slopes of stiff fissured clay, where the slope angles are 3° and steeper. It is suggested that, whilst these slopes are stable under present day conditions, the slip surfaces must have been formed as the result of periglacial activity. The presence of these discontinuities, which have shearing resistances at or near their residual values (Skempton 1964), is the governing factor affecting the maximum possible natural slope angle and also the stability of any engineering works that may be constructed in the area.

In the case of the investigations in Kent it has been possible to recognize three separate periods of solifluction corresponding to the Saale Glaciation, the Main Weichselian and Zone III of the Late Glacial.
Photo-interpretation of boulder clay areas as an aid to engineering geological studies
Authors: Norman John Wakelin
Published: November 2007

The over-all view of the environment, the exploitation of vertical scale exaggeration and the use of film sensitive to soil moisture content, enables an experienced photo-interpreter to produce information that can supplement engineering geology studies made directly at the site. Reconnaissance soil mapping can be carried out in glacial areas by geomorphological methods supported by drainage, gully, vegetal and tonal characteristics, together with rapid field checks in selected characteristic areas.

Numerical values are given for the proportion of buried bedrock features which have been detected in test areas covered with boulder clay, as well as for changes in detectability with variables such as the depth of superficial cover, the type of land use, and air photograph quality. The criteria for the identification of buried features are discussed, as well as the detection of landslides, subsidence, drainage and flooding problems, and the choice of airphoto-graph scale, materials and processes for engineering geological studies.
The degradation of Lias clay slopes in an area of the east Midlands
Authors: Chandler Richard John
Published: November 2007

This paper presents a survey of slopes in an area of Rutland and Northamptonshire where the valley sides are formed of Upper Lias Clay capped by the Inferior Oolite. The observations support the pattern of degradation observed for natural slopes of London Clay. The slopes are considered in their regional context, from which it is seen that the steeper areas (where slides are most likely to occur) are encountered just beneath the Inferior Oolite and at valley heads. Valley asymmetry is also found, southern slopes being generally the steeper. Attention is drawn to agricultural activities which may partly or completely conceal the presence of landslides.
The hydrogeological investigation of fissure-flow by borehole logging techniques
Authors: Tate Tom Keith , Robertson Anne Shirley , Gray David Alfred
Published: November 2007

The instrumentation and techniques developed for the investigation of fissure-flow in consolidated aquifers are described and illustrated by three case histories. The use of closed-circuit underwater television inspection of boreholes is outlined and consideration is given to the implications of flow rates by analyses of the tritium contents of some water samples.
Some aspects of the Triassic aquifer in east Devon and west Somerset
Authors: Sherrell Frederick William
Published: November 2007

The paper reviews the geology of the Triassic in east Devon and west Somerset, presenting new information relating to aquifer thickness and the changes in particle size, which takes place latitudinally. These factors, together with the degree of cementation of the strata, are shown to have a great influence on infiltration, storage and yield. The chemistry of the ground-water is described, and the combined influences of the geology and ground-water chemistry are considered, in relation to the future development of the aquifer.
Terminology for describing the spacing of discontinuities of rock masses
Authors: Watkins Mervyn David
Published: November 2007

T
erms
which precisely describe the spacing of joints and bedding planes are needed in engineering investigations of rock masses. Several schemes have been used by geologists for the description of bedding units and these were summarized by Ingram (1954). Because of their variations and irregular scales he proposed a classification based on a logarithmic scale starting at 10 mm. His system has been used by many geologists but it is considered inadequate at the widely spaced end for much engineering work. More recently schemes have been defined by workers in engineering geology and rock mechanics with subdivisions for the wider spacings. Some of the classifications are shown in Table 1.

Different descriptive terms for the spacings of bedding planes and joints,
viz.
thick-thin, close-wide, are preferred in order to emphasize their generally different characteristics, e.g. the abrupt change in lithology, permeability and strength which can occur at bedding planes. This follows Deere (1952) whose scheme has been reproduced in text books by Obert & Duvall (1967) and Stagg & Zienkiewicz (1968). His classification is not, however, completely regular, it does not conform with common geological usage and more subdivision is considered necessary below 300 mm (12 in) spacing.

Although there is reluctance at proposing an additional scheme, it is considered that a classification combining features of some previous scheme is required. A system which defined the size of the unit blocks of intact rock as an extension of the scale used for size distribution (
c.p.
2001) was considered. Such a
Some geotechnical and sedimentary aspects of ballclays from Devon
Authors: Best Robert , Fookes Peter George
Published: November 2007

Some geotechnical properties of the ballclays of Devon have been related to their mineralogical composition, sedimentary depositional environment and tectonic setting. Small scale sedimentological structures of these predominantly disordered' kaolinitic clays indicate shallow water deposition in a fluvio-lacustrine environment which existed during Oligocene times in the Lustleigh-Sticklepath fault zone. The two principal types of ballclay, the stoneware and whiteware ceramic varieties, have consistently different negative liquidity indices which imply different degrees of overconsolidation. The differences of consistency between the stoneware and whiteware ballclays are considered to have arisen as a result of variations in the intensity of desiccation to which the individual beds of ballclay were subjected shortly after deposition, when receding flood waters allowed drying of the fresh sediment.

The stoneware ballclays are typically stiff to hard, apparently 'intact' clays found inter-bedded with silts and sands, whilst the whiteware clays are hard or very hard, highly fissured and slickensided slightly lignitic clays which occur in close association with lignite seams and in many respects resemble underclays from coal-bearing sequences. Overconsolidation is considered to result principally from desiccation of the individual beds of clay, hence estimates of the former maximum thickness of the ballclay deposits within the Lustleigh-Sticklepath fault zone from one-dimensional consolidation tests using undisturbed and remoulded specimens are precluded.
Engineering problems caused by fossil permafrost features in the English Midlands
Authors: Morgan Alan Vivian
Published: November 2007

Trench sections excavated for a gas pipe-line north of Wolverhampton were observed to collapse because of sand infilled wedges intersecting them. The wedges form the remnants of fossil ice-wedge casts which developed in the West Midlands following the retreat of the last ice. Selected examples of collapse features are illustrated and remedial action suggested.
Engineering geology and soil mechanics in project evaluation
Authors: Subramaniam A. Siva
Published: November 2007

A
spects of project evaluation
which come within the ambit of engineering geologists and soils engineers arise from the physical setting of the project. They are, firstly, concerned to observe and infer the distribution of soil and rocks and the ground water regime, secondly, to assess their implications for the construction of foundations for the structures which comprise the project. The first is geology and the second is foundation engineering. Foundation engineering is a subtle combination of geology and soil mechanics with the intuitive art of judgement and innovation where experience plays an important role. The role of the engineering geologist and the soils engineer is to ensure that the appropriate combination of geology and soil mechanics is used in the assessment of foundation engineering problems.

In the early days, theoretical methods of soil mechanics combined with improved techniques of exploration promised to eliminate the necessity for depending on geological information. For a period engineers felt that it was only a question of time until all the problems in the field of sub-surface engineering, like those in steel and concrete design, could be solved by theoretical methods using values determined by laboratory tests. However, the practical application of soil mechanics, coupled with field observation of performance, often showed large discrepancies between the forecast and the actual events. Re-assessment of case histories invariably showed that such discrepancies were essentially dependent on the geological characteristics of the soils and rocks.

Blind exploration of sites gave way to planned site investigations based on the
The development of the water resources of Northern Ireland progress towards integration
Authors: Manning Peter Inglett
Published: November 2007

The paper presents a comprehensive account of the occurrence and distribution of groundwater in Northern Ireland, relating location of potential groundwater sources to the position of the aquifers in the stratigraphical column. Future developments in the management field are reviewed and an appendix provides a discussion of the past legislative history in Northern Ireland with regard to the control of water resources.
Reservoirs for pumped storage
Authors: Anderson J. G. C.
Published: November 2007

Pumped storage projects involve major civil engineering works costing tens of millions of pounds but are nevertheless an efficient way of storing energy and economically a better method of meeting peak loads than building bigger generating stations. Because they require special environments, reservoirs for pumped storage raise difficult problems in engineering geology.

Such schemes operate with maximum efficiency with heads of the order of 1000 ft and relatively short hydraulic systems. There is no need for natural catchment at the upper reservoir, since water is pumped, but for the same reason the engineering geologist must ensure that minimum leakage will occur. As high-level, small corrie/cwm basins are likely to be used, the upper reservoir site may need to be topographically and geologically suitable for the high dam required to gain capacity.

The limitations of very brief starting time and high output impose severe limits on the lengths of tunnels, etc. and on the position of the power station in the system. The geologist, therefore, has not the same freedom to suggest geologically better tunnel routes and power station sites, and has to give an opinion whether the rocks present are suitable for large tunnels and underground power station chambers.

At the lower reservoir site, unless there is a considerable natural inflow, leakage must again be reduced to a minimum. Moreover, as the lower reservoir is often in developed areas, very careful account must be taken of possible alterations to the water table and of the results of large and frequent
Embankments on soft alluvial ground
Authors: Rowe P.W.
Published: November 2007

Following a brief statement of the normal engineering solutions, soil mechanics design procedures are discussed in relation to site investigation, sampling, testing techniques and analysis.

The arrangement of the geological features of a soft deposit dominates all stages of design. Soil specimens have to be representative of the strata in location, quality and size for adequate prediction of the strength and the consolidation of alluvial deposits. Permeable fabric normally allows the foundations of small embankments (5 m) to consolidate rapidly but larger embankments may require a limited number of sand drains to avoid serious pos-construction settlement.

Centrifuge studies allow a check on design provided the strata and their fabric are properly represented in the model.
The role of The Geological Survey of Northern Ireland in highway construction problems
Authors: Manning Peter Inglett
Published: November 2007

The relevance of geological factors in the selection of routes, and at later stages in feasibility studies and in construction of highways, is shown by reference to case histories dealt with by The Geological Survey of Northern Ireland. Specific examples include the Ml and M2 (Northern Ireland), Belfast Urban Motorway (Phase 1) and Belfast Outer Ring Road.
The stability of a rock slope containing a wedge resting on two intersecting discontinuities
Authors: Hoek E. , Bray J. W. , Boyd J. M.
Published: November 2007

The problem of the stability of a rock slope containing a three-dimensional wedge resting on two intersecting discontinuities is analyzed by means of engineering graphics, using spherical projections and analytically. The effects of an obliquely inclined upper slope surface, a tension crack behind the slope face, water within the tension crack and on the sliding surfaces and an external force, due for example to a cable anchor, are included in the analysis. Resistance to sliding results from both friction and cohesion on the sliding surfaces.

A worked example, using all three methods, is given.
An investigation of the stability of a proposed hotel in the Avon Gorge, Bristol
Authors: Larnach William J. , Bradshaw Reginald
Published: November 2007

The proposed multi-storey building was to be located on a site which slopes steeply towards the River Avon. The site was close to one, at a lower level, which had shown evidence of local instability, and which formed the subject of an investigation by
Skempton & Henkel (1959)
. The previous work showed that it was possible for material lying above a clay layer to slide obliquely outwards towards the Avon Gorge. A new site investigation was therefore undertaken to discover the nature, extent and frequency of other clay layers which might be present, to assess the condition of the limestones, and to discover the site groundwater conditions. Stability analyses were made using the sliding model postulated by Skempton & Henkel. Since porewater pressure is zero or nearly so the results of these analyses can be simply presented.

It was concluded that high level foundations were not suitable for this building on this site, and that the foundation loads should be transmitted by means of piers of variable lengths up to a maximum of 140 ft, through the interbedded clay layers to sound limestone. The same basic analysis was used to investigate the stability of the excavated faces (about 30 ft deep) at the rear of the site.
A Regional Engineering Geological Study of the London Clay in the London and Hampshire Basins
Authors: Burnett Alister D. , Fookes Peter G.
Published: November 2007

The study was devised to investigate certain regional relationships between geological and engineering index properties of the London Clay. Geological data including lithology, bed thickness and structural contours and an important new sedimentological and palaeontological zonation system of the London Clay were related to the detailed mineralogy of the clay. The mineralogical and lithological characteristics (mainly grading) were found to have a fairly close relationship to engineering index properties of the clay and from this various geological and geotechnical properties were linked.

Geological data were mainly gathered from published information and geotechnical data from several Firms and Organizations working in the London and Hampshire Basin areas. Mineralogical data were obtained by analysis of over 300 samples from 22 field sections of the London Clay.

Examples on a regional scale of computer and manual plots of clay zones are given as well as maps showing palaeogeography, mineralogy and engineering property distributions. Examples of the geological and geotechnical depth profiles which were used to establish relations between lithology, zonation, mineralogy and geotechnical properties are also given.

The results of some laboratory experiments to study the processes and effects of sediment deposition, erosion and weathering are discussed and related to the field work.

Although the work can only be considered as a pilot study the results in the form of maps, sections and general conclusions indicate that future development of the techniques should be of geological and geotechnical interest and value in predicting the general engineering conditions in new sites within the area.
Collapsing behaviour of some loess soils from Normandy
Authors: Audric T. , Bouquier L.
Published: November 2007

The susceptibility to collapse of loess soils from Normandy was examined in the triaxal apparatus both at natural moisture content (UU test), and after saturation (CU test). In order to prevent the sample from collapsing before the CU test, the lateral stress was applied before the samples were saturated.

Saturated loess soils show two very different types of behaviour depending on the void ratio. At high void ratios the stress path shows a collapsing structure which does not occur at low void ratios. The behaviour at natural unsaturated moisture content seems to depend on the clay content.

After a comparison with some results obtained on loess soils from the Paris area, the following conclusions are established:

that there is an analogy between the behaviour of collapsing loess soils and that of sensitive clays,

that the Feda criterion may be used to predict the collapse of a sample
(Feda 1966)
, and

that there are difficulties in using this criterion for practical problems due to the
in situ
variation of void ratio.