bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogeology of the Kufra and Sirte basins, eastern Libya
Authors: Wright E. P. , Benfield A. C. , Edmunds W. M. , Kitching R. 
Published: November 2007

Summary
Two major sedimentary basins occur in eastern Libya. The uppermost horizons in each—post-Eocene in the Sirte and Cretaceous Nubian in the Kufra basin—constitute regional hydrogeological systems. The deposits of the Sirte basin include mainly fluviatile sands and clays in the S with marine carbonates and sandy carbonates with some evaporites progressively increasing to the north. In addition to a northwards thickening of the deposits there is an ‘inwards increase’ which attains a maximum thickness of about 1800 m along a broad N-S trending axial trough. The Nubian sandstone of the Kufra basin has a maximum thickness of 900 m and includes mainly cross-bedded sandstones, subordinate shales and conglomerates, which are fluvio-glacial and limnic in origin.

The Cretaceous sandstone aquifer in the Kufra basin is essentially phreatic and groundwater flow is to the northeastwards discharging into the main Nubian artesian basin of Egypt. Present development of the aquifer occurs at only a few locations but at these the water quality is very fresh with dissolved solids typically less than 100 mg/1. The basin is bounded to W and S by highlands from which appreciable run-off can be assumed. Although not measured, assumptions of recharge from run-off of some 10–20% of annual rainfall over the elevated areas seems not unreasonable; this is approximately equivalent to the computed order of outflow from the basin of between 70–160 M m
3
/a based on transmissivity and piezometric gradient. Vertical recharge is unlikely to occur over the main basin where the rainfall is probably less than 3 mm/a. The age of the water at Kufra in the north of the basin is in excess of 30 000 years. The phreatic aquifer cannot therefore be in equilibrium with current recharge but it is believed that an approach to equilibrium may exist in marginal recharge areas.

The groundwater in the S of the Sirte basin is fresh but in the N it becomes brackish to saline in the direction of flow. The known groundwater ages range from 30 000 to 5000 years BP and fall into three main groups. Water from recent recharge may also exist in the uppermost phreatic levels. Various evolutionary trends have been considered and modelling techniques are used to assist elucidation. The results demonstrate that present water levels may be fairly close to equilibrium, with recharge to the aquifer system occurring from several sources including lateral inflow from the Kufra basin, marginal recharge via run-off from the highlands to the W and SW, and direct recharge from precipitation in the N of the basin. Discharge occurs in the N into sabkhat areas between the Gulf of Sirte and Qattara.
An approach to laboratory testing of geotextiles
Authors: McGown A. , Andrawes K. Z. 
Published: November 2007

Summary
Recently, geotextiles have been employed in permanent works with consequent long term requirements for their satisfactory performance. The need has grown, therefore, for testing which provides data for specifications, quality control and design purposes. This paper points out that geotextiles are a group of materials which have widely differing internal structural arrangements. In many cases they are highly compressible and confinement can significantly modify their properties, in particular their pore space, load-extension and surface friction properties. These properties control the basic functions of separation, filtration, drainage-in-the-plane and reinforcement. As the modifications induced by confinement vary with the level and nature of the confining material, distinction has been made between in-isolation and in-soil testing. Recently developed apparatuses and test methods for both test modes are described and typical data are given. The usefulness of these in-isolation and in-soil tests for specifications, quality control and design purposes are then identified.
Settlement of two oil tanks on Kaduna lateritic soils in Nigeria
Authors: Ola S. A. 
Published: November 2007

Summary
The present work has given an opportunity of studying the concepts of elastic settlements using an ideal field situation of an unsaturated, relatively uniform and homogeneous soil loaded for a very short period. For the cases cited in this paper, the calculated elastic plus consolidation settlements agree reasonably well with settlements observed during the water tests. The consolidation settlement was found to be relatively insignificant and for the case of unsaturated lateritic soil loaded for a relatively short period, the elastic settlement can be used to predict settlements.
Application of consolidation theory for peat to the design of a reclamation scheme by preloading
Authors: Berry P. L. 
Published: November 2007

Summary
A brief review is given of the consolidation theory for fibrous peat and additional solutions presented for the important practical case of a time-dependent rate of loading. The application of the theory is illustrated by reference to a recent study to assess the possible use of preloading to reclaim some 200 acres of peat land for building purposes. The investigation involved a series of single increment vertical consolidation and permeability tests on 250 mm diam. by 75 mm thick undisturbed samples of the peat. The increments were maintained for up to 3 years, to define the long-term secondary compression behaviour. A summary of the results is presented, together with the predicted field consolidation curve and estimate of the required surcharge.
Comparisons between real and predicted geology in tunnels: examples from recent cases
Authors: West Graham 
Published: November 2007

Summary
Since 1975 the Transport and Road Research Laboratory has been carrying out case history studies of site investigations for tunnels; the aims are to bring out the essentials of good practice, show where improvements are needed and put on record the construction experience.
The paper reports the lessons learnt from the last five of these case histories. The tunnel projects are the Liverpool Loop and Link Tunnels, the proposed extension of the Jubilee Line, the Cardiff Cable Tunnel, the Dinorwic Diversion Tunnel and the Kielder Aqueduct Tunnels. The geology of the sites varies from Cambrian slates and grits to Eocene London Clay.
The general conclusions are that good use was made of preliminary information on ground conditions, and that the geology of the sites was usually well appreciated. Boreholes, samples and the use of test results were matters where improvements could be made. Geophysical surveying gave useful results, and recording the geology as revealed during construction was done satisfactorily. Use of inclined boreholes, trial shafts and the borehole camera are among the suggestions made.
Specifications for bulk and selected fill materials in highway and other projects
Authors: Horner P. C. 
Published: November 2007

Summary

Bulk and selected fills are commonly required for the construction of embankments, pavements etc. In the UK many civil engineering contracts are carried out under the ICE form of contract, which incorporates a specification that defines the nature and properties of the materials that may be used and the limitations on construction methods that may be employed. Specifications are frequently unique documents that meet the specific needs of the contract, although many are based, at least in part, on the
Specification for Road and Bridge Works,
Department of Transport (1976a)
. As with other ‘standards’, experience and local conditions have resulted, in recent years, in the production of alternative or special specification clauses, some of which have caused difficulties in interpretation and quantification at the tender stage, and interpretation and implementation at the construction stage. This has in a number of cases led to contractual disputes or increased costs to the contractor and/or employer. Some of the specification clauses that have led to disputes are described, together with illustrations on how they may be improved.
Geomorphological observations as aids to the design of coast protection works on a part of the Dee estuary
Authors: Pitts John 
Published: November 2007

Summary

A section of the southeast shore of the Dee estuary is occupied by unstable cliffs formed of a complex succession of glacial deposits. Design of remedial works has necessitated an investigation of the nature and balance of geomorphological processes operating. Between 1973 and the present, a balance over a year has generally been achieved between failure of a clayey flow till in the upper cliff and erosion of the resulting colluvium from the toe. During exceptional storms, colluvium and
in situ
cohesive and non-cohesive materials are eroded, producing a rapid and larger-scale response at the crown of the slope. During winter, high pore water pressures are generated in perched water tables within the succession.

Recent stabilization works at the toe in one downstream section appear to have caused severe toe erosion and slope instability over a distance of approximately 73 m of cliff line immediately upstream of the works.
Geomorphological studies have also indicated appropriate angles for naturally stable slopes within this mixed succession. Grading or backfilling of the toe to achieve these specified slope angles, and toe protection with or without drainage, have been undertaken or are planned.
Soft rocks and soils
Authors: Hooper J. W. 
Published: November 2007

Review of the joint meeting of the Engineering Group and the British Geotechnical Society held at Burlington House on 8 February 1983.

Dr A. B. Hawkins, Chairman of the Engineering Group, welcomed a capacity audience to the Meeting. The presentation by Mr C. J. Day of Dames and Moore entitled ‘Criteria for classifying soil and rock for planning purposes’ was concerned with the broad classification of soil and rock that would prove useful to planners in the complex process of initiating large projects. He stressed that the planning criteria themselves rather than the engineering parameters are the issues and that resolution of these issues demands a wide variety of value judgements. Each issue, it was stated, may have very wide data needs, for example twenty to thirty planning elements, only some of which would be the normal geotechnical data bases. Digital mapping and digital processing of these planning elements is an essential tool for planning. An example of the siting of a nuclear power station in the western United States based on digital mapping was given.
The speaker went on to discuss the geologist's role in the planning study, giving as an example planning the use of underground space. He viewed the geologist's role as a composite one involving geomechanics, construction practice and stratigraphy. He stated that any classification should have as its domain the overall project, and should not be incompatible with any of the existing site specific geomechanical classifications. Using construction techniques as a basis of classification four
Some engineering implications of chemical weathering of pyritic shale
Authors: Steward H. E. , Cripps J. C. 
Published: November 2007

Summary
Previous research at the site of a landslip at Mam Tor, Derbyshire, has linked the oxidation of pyrite in Edale Shale to the generation of acid groundwater. Chemical analysis of surface seepages suggests that reactions occur between this acid water and sedimentary minerals, including clays.
The objective of the present research is to relate changes caused by chemical weathering to modifications of the engineering properties of those materials. It has been found that in closed system acid leaching experiments, some constituents of shale react very rapidly. In order to quantify these changes in terms of the residual shear strength of shale, a Bromhead Ring Shear apparatus has been modified so that the composition of pore solutions may be altered during shearing. These tests indicate that the residual shear strength of the shale is sensitive to modification of pore solution composition. The changes are rapid, reversible and apparently chemically analogous to those at Mam Tor.
Since the bulk properties of weathered shale depend both on the type of solid material and the pore solutions present, the weathering of Edale Shale is discussed in terms of solid and solution phase modifications.
Controls on contaminant migration at the Villa Farm Lagoons
Authors: Williams G. M. , Ross C. A. M. , Stuart A. , Hitchman S. P. , Alexander L. S. 
Published: November 2007

Summary
The disposal of liquid wastes containing heavy metals and organic solvents into lagoons excavated to beneath the water table in a shallow, unconsolidated sand aquifer has resulted in local groundwater pollution. The development of the pollution plume appears to be controlled by the morphology of the aquifer, the distribution of permeability within it and the head distribution in the vicinity of the lagoons. On the basis of redox reactions three geochemical zones have been identified down hydraulic gradient in the transition from strongly reducing conditions near the lagoon and at the base of the aquifer to oxidizing conditions in natural groundwater. Heavy metals are attenuated within a short distance of the lagoons, probably as a result of precipitation as sulphides and carbonates, but organic wastes have been found in excess of 300 m from the site. With increasing distance from the lagoons changes in bacterial populations and the character of organic compounds present at the base of the aquifer suggest that organic transformations are occurring despite little change in the concentration of total organic carbon, although ultimately biodegradation to methane and carbon dioxide takes place. Studies are continuing in order to develop a three dimensional mathematical model integrating chemical reactions with groundwater flow.
Preliminary observations on the design and construction of a four-lane highway through expansive clay in Cyprus
Authors: Cottiss G. I. 
Published: November 2007

Summary
A case history is presented describing some aspects of the design process and the early stages of construction of a four-lane highway across an outcrop of expansive clay in southern Cyprus.
The clay, of the Moni Formation, affects 7.5 km of the total 85 km of the new road alignment between Nicosia and Limassol. A special construction treatment was devised to deal with anticipated swell-pressures from the clay beneath the pavement construction. The original concepts were reviewed and revised after the contractor took over the site. During the first half of the contract period, following new investigations, the standard cross sections were changed and the treatment was extended.
A minimum surcharge of 2 m of construction (filling plus pavement layers) was provided throughout the 7.5 km of cut and fill to balance the swell-pressures. Intercepting drains were also provided to prevent ground water entering the clay sub-grade layers. This minimum ground loading was adopted after a study of potential swell and from calculations made using measured soil classification values and a theoretical relationship devised elsewhere.
Cuttings in the clay were originally designed at 1:2 (vertical: horizontal) but a major slope failure shortly after excavation led to a flattening of this particular face and gave an indication that existing factors of safety on slope stability were low. There are old landslips on the natural slopes across which the highway runs. An instruction was given to the contractor to locate all waste tips away from these slopes to prevent re-mobilization of slipping.
Construction in tidal rivers: an overview
Authors: Coffey J. R. 
Published: November 2007

Summary
For centuries man has sought to achieve some beneficial change, usually for navigation, to tidal rivers or estuaries. In response to both pressure on land in coastal areas and to the increasing acceptance of the concepts of multiple land use, construction in areas of tidal waters has become more complex. Water storage, recreational and power generation schemes are typical examples.
With the optimum areas already utilized, construction work represents an increasingly difficult challenge in terms of site evaluation. Data required to achieve this objective include a wide range of aspects such as tidal cycles and sediment movement in terms of the likely modification following construction. These are essential for assessing the beneficial or damaging consequences of man-induced changes.
Three case histories are presented, summarized from existing literature, to illustrate the complex interplay and variable nature of tidal river and estuary systems. The purpose is to demonstrate the impact of changes following construction, and to show that these may have influenced decisions on details of the engineering scheme at the time of design, and the environment of the tidal reaches and the immediate surrounding areas.
Depositional characteristics of estuarine alluvium: some engineering implications
Authors: Hawkins A. B. 
Published: November 2007

Summary
A review of sea level change during the Flandrian period concludes that a steady rather than oscillatory rise has occurred. In Britain the eustatic rise has been modified by isostatic effects; these are reflected in slightly different sea level curves for the Severn, Thames and Clyde estuaries. Higher undrained shear strengths recorded in the outer Thames estuary and taken to imply a transgressive/regressive sequence are inconclusive of an oscillatory curve; such desiccated horizons are not present in the Severn Levels.
The pattern of sea level rise is reflected in the nature of the sediment. The characteristics of a silty sand deposited during a period of rapid sea level rise and overlain by a laminated mud/silty sand sequence with occasional peat horizons are discussed. A proposed description for laminae thickness is presented. Bioturbation may modify the sediment character of tidal river environments.
Tidal pills, common in salt marsh areas, are difficult to detect when infilled. The geotechnical affects of the features are related to their different consolidation properties and skin friction compared with the normally deposited (layered) sediments. The importance of laminations in soils to lateral pore water dissipation and the implications for road embankment construction are considered.
Re-levelling a gas holder at Rhyl
Authors: Greenwood D. A. 
Published: November 2007

Summary
Due to ground excavation 13 m from a gas holder at Rhyl, North Wales, the gas holder settled 60 mm. The settlement was at least in part due to piping of sands deep below the foundations of the holder.
Grouting to recompact sands loosened by the piping stabilized the ground and allowed pressure grouting to be used to restore the gas holder to its original levels. Little response to the grouting was seen until a substantial proportion had been pumped when a sudden change indicated the onset of a second phase of the process, the restoration of effective overburden pressure being followed by a controlled ground rise.
The classification of mudrocks for engineering purposes
Authors: Grainger Peter 
Published: November 2007

Summary

A classification of mudrocks for engineering purposes was considered necessary in order to improve the common qualitative use of a variety of geological terms. There has been a lack of agreement between authors on the precise definition of these terms. Mudrock is defined as a fine- to very finegrained, siliciclastic sediment or sedimentary rock. Quantitative boundaries for this group of rocks are proposed using meaningful soil and rock index parameters, at changes in mechanical or material behaviour. The basic division is between fine-grained engineering soil, non-durable rock and durable rock, at compressive strengths of 0.6 and 3.6 MN/m
2
. The mudrock soils are classified according to the British Standard Classification of Soils (BSCS) with the addition of the term silty clay. Fissile or anisotropic rocks are termed shales, including clayshales where non-durable. Isotropic ones are classed as siltstones, mudstones and claystones according to their quartz contents. Tectonically induced strength and fabric anisotropy can be important and may result in slaty shales where the rock microfabric has been well aligned. An upper compressive strength limit of 100 MN/m
2
is proposed to distinguish diagenetic mudrocks from their metamorphic equivalents.
Groundwater abstraction from Basement Complex areas of Africa
Authors: Clark Lewis 
Published: November 2007

Summary
The Basement Complex of Africa is a heterogeneous mixture of crystalline rocks, predominantly of a granitic or gneissose character. Groundwater occurs within these crystalline rocks in fissures or in the superficial weathered zones. The rocks are relatively impermeable and groundwater can occur in the superficial deposits overlying the bedrock. There are no regional aquifers in Basement Complex country and each site has to be treated as unique.

The occurrence of groundwater in fissure systems or weathered zones means that the resources at any one site are finite and relatively small. Well yields similarly are limited, rarely exceeding 500 m
3
/day. In this situation the groundwater reservoir is structurally controlled and, therefore, susceptible to investigation by a variety of techniques including photogeology and geophysics. Furthermore, although each borehole is unique, the data from all the boreholes in a specific area can be analysed statistically to produce well design criteria.

The limited resources within the crystalline basement can lead to multiple-source solutions to supply problems where every alternative has to be examined. Shafts or cisterns, for example, may be used. The superficial deposits commonly hold significant resources of water and, in certain circumstances, can give much higher yields than the Basement Complex rocks. This superficial water can be tapped through bores, shafts or trenches, and the resource can be enhanced by water harvesting techniques.
The development of a resource is instigated for a specific purpose—a village water supply or an industrial supply. It is important that the planners and engineers involved in putting forward proposals recognise the limitations of groundwater abstraction in Basement areas. The water supply must be proven and developed before the costly infra structure—the factory or distribution network—is built.