bluuebunny/crossref_metadata_2025 huggingface dataset:
Some engineering implications of chemical weathering of pyritic shale
Authors: Steward H. E. , Cripps J. C.
Published: November 2007

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

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

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

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

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

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

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.
Discussion on ‘Engineering geomorphological investigations of a possible landslide, Killiecrankie Pass, Scotland’ by Robert Chaplow
Authors: Allen Arthur C.
Published: November 2007

A. C. A
llen
writes: Chaplow comments in his summary and introduction on previous conventional site investigations. The Report of the Geotechnical Survey commissioned by the Scottish Development Department from Allen, Gordon & Co., Consulting Civil Engineers, in December 1972 was issued in September 1973. It dealt with all geotechnical aspects of the full length of the road improvement in the Pass and in relation to the site investigation it covered all stages from deciding upon what should be undertaken, issuing tender documents, recommending the contractor, supervising the investigation and interpreting the report received. From considering four choices of route through the Pass, the Report recommended the adoption of a dual carriageway in cut and on embankment, which was detailed on an alignment close to one of the four choices. Possibilities of tunnel and elevated roadway solutions had been considered and rejected on account of excessive cost.

The landslide with a recognised poorly-developed surface drainage system, to which Chaplow refers, affects a length of about 60 m in the two-kilometre-long Pass and it was identified as part of a 600 m long transverse feature between the top of the east side of the Pass and the railway at the bottom, which comprised original undisturbed glacial deposits and slipped reconstituted deposits lying in less consolidated form over, and often between, the ridges of the original glacial deposits. With provision of reasonable drainage, it was considered that the feature would not present any great difficulty during construction or significant risk thereafter, which corresponds.
Groundwater abstraction from Basement Complex areas of Africa
Authors: Clark Lewis
Published: November 2007

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.
The influence of ground and groundwater geochemistry on construction in the Middle East
Authors: Fookes P. G. , French W. J. , Rice S. M. M.
Published: November 2007

Many parts of the world's extensive hot drylands pose significant problems for the civil engineer because of chemically aggressive and changing ground conditions. The most important areas are generally the broad flat coastal strips of more recent sediment, for these commonly contain abundant sulphate as gypsum and anhydrite and have widespread surface or near-surface crusts of halite.

The coastal water and groundwater in these regions are usually sulphate and chloride rich, moving slowly through the sediments because of rapid evaporation of the groundwater via the capillary fringe into the drier atmosphere. This movement of groundwater accelerates solution and precipitation of the more soluble minerals, the greater the flow rate the more rapid the compositional change in the sediments—sufficiently rapidly to be of engineering significance. The engineering works themselves can effect significant changes in the ground chemistry and this is most often brought about by changing the position of the water table or the capillary fringe, by dewatering, or raising ground levels by depositing fill. In addition to the significant effect of salts on results of standard engineering tests, the other most likely problems created by the chemical changes are: settlement due to solution in flowing groundwater, heave due to crystallization from groundwater or by reaction between soils and groundwater, and the creation of a chemically aggressive environment in foundations.

The properties of these groundwater-soil systems are reviewed from the point of view of field observations and some large-scale experiments which give indications of the magnitudes and rates of the chemical processes. Two case histories are cited by way of illustration-Dubai Dry Dock and the Harbour Works at Mina Jebel Ali, Dubai. The Dry Dock represents an example of settlement effected by the solution of gypsum from lithified sediments through which seawater was passing, and the Harbour Works show how groundwater and fill chemistry have been changed in the few years required for the construction works.
Rock pressure coefficient for design of rock retaining structures
Authors: Whiteside P.
Published: November 2007

When designing rock retaining structures such as basement walls it is common practice to use a lateral ground pressure coefficient such as that derived for a granular soil. This paper derives a general rock pressure coefficient applicable to a jointed rock mass with potential plane or wedge failures in any direction and including the effect of surcharge and water pressure. Use of this rock pressure coefficient will in very many cases enable a more realistic and economical design to be adopted.
Completely weathered granite—soil or rock?
Authors: Howat M. D.
Published: November 2007

The construction of a mass transit railway in Hong Kong and Kowloon provided opportunities to study the properties of completely weathered granite both in engineering site investigation boreholes and
in situ
stress measurements in earth pressure cells in the walls of excavations up to 30 m deep. The shear strength profiles of the material are compared with existing models of soil and rock behaviour, and conclusions are made on problems such as the existence of true cohesion, the effect of laboratory saturation, and the influence of relic joints.
Applications of fluorescent dye tracers in the planning and hydrological appraisal of sanitary landfills
Authors: Smart P. L.
Published: November 2007

Four applications of artificial tracers in the study of sanitary landfill sites are identified; confirmation of leachate contamination, determination of on-site hydrology, determination of hydraulic properties of landfill materials and prediction of leachate contamination and dilution. These applications are illustrated by seven tracing experiments undertaken at a landfill site in the Jurassic Great Oolite Limestone of the Cotswolds using fluorescent dye tracers. The tracers proved non-conservative, which limited their use in determination of hydraulic properties, but were still detectable over 5 months after injection. Background fluorescence due to organic materials in landfill leachate and chemical instability caused problems in analysis, but these could be overcome. Overall the tests were successful in identifying the sources and paths of leachate leakage in the landfill, permitting design of effective remedial measures, and in demonstrating the risks of leachate contamination at surface streams and springs in the vicinity.
J. P
itts
replies
Authors: Pitts John
Published: November 2007

Agreement over the form of a paper will not necessarily be universal. The alternative methodology and table proposed by Morton and Sayer would tend to suggest that more is known about the geology and engineering geology of Singapore than is actually the case. Single ‘typical’ values presented to summarize soil properties are almost inevitably misleading. Singapore geology typifies the problem. Furthermore, Morton and Sayer present an example which appears to faithfully follow the system adopted during the Mass Rapid Transit site investigation, which, in particular with respect to weathering grades, has caused a good deal of (at least initial) confusion. The form of a classification does, of course, depend upon the purpose to which it is to be put. One use may be to assess conditions for foundation purposes. In such a case, the classification presented by Morton and Sayer would probably be too coarse. There are, however, other uses.

The suggestion that a deposit can be classified on the basis of origin, process of accumulation, and geomorphology is, of course, reasonable. However, it is difficult to agree to this being automatically taken to the further stage of accepting that general quantitative characteristics apply to the deposits. One fact which is perhaps becoming evident in Singapore is that variability is actually a characteristic of many materials.

The quantitative information presented in the paper for the Marine Clay is for perhaps the most intensively investigated of deposits in Singapore. The great variation in properties have been dealt with by Tan (1983)
Groundwater and aquifers; an overview of ‘exotic’ uses
Authors: Edworthy K. J. , Puri S.
Published: November 2007

There is a range of uses for groundwater and aquifers, mostly non-water supply uses, which have been termed ‘exotic’. These uses can be categorized into four distinct fields: fluid storage and waste disposal, including deep-well injection; energy conservation, including storage of fossil fuel-generated energy (as heat or pressure) and the extraction of solar energy from groundwater; subsurface
in situ
leaching of economic minerals; and groundwater quality management. Some details of each of these fields of application are presented to illustrate their essential multi-disciplinary nature and also the benefits that can arise from their use. Much more intensive investigation than normal is considered necessary to obtain the detailed site-specific data that any application would require. This would also have to be linked with an adequate regional monitoring system, which protects potable groundwater and other minerals. Possible applications in the United Kingdom are considered.
The relationship of aquifer petrophysics to hydrocarbon evaluation
Authors: Worthington P. F.
Published: November 2007

Well log evaluation for fluid hydrocarbons has always drawn upon petrophysical relationships for the aquifer zone where the water saturation is unity and the resultingly less complex petrophysical regime can be used for control. This dependence upon aquifer petrophysics has traditionally centred on the Archie equations which are strictly valid only for clean sands. Research directed at the establishment of more generally applicable equations for the evaluation of clean or shaly hydrocarbon reservoirs has again been based initially on the aquifer zone to avoid water saturation as a complicating parameter. These equations, which conventionally draw upon electrical resistivity concepts, are demonstrably equivalent to those used in the water industry. It is proposed that they form part of a larger family of petrophysical relationships which describe the electrical behaviour of water-saturated reservoir rocks as a whole. This behaviour is seen to be consistent for arenaceous core plugs representing a wide range of petrophysical characteristics and it might therefore describe a type pattern which is retained through to the hydrocarbon zone.
Simulation of gas and oil flow in hydrocarbon reservoirs
Authors: Cole P. , Collins P. A.
Published: November 2007

The non-specialist is introduced to the uses made of numerical simulation in modelling the behaviour and performance of hydrocarbon reservoirs. Hydrocarbon reservoir modelling can be compared with groundwater modelling, but is generally more complex, commonly dealing with multiphase fluid systems in two or three dimensions. Both finite difference and finite element techniques are used to solve numerically the equations of motion. The application of two powerful models, PORES and PROGRESS, illustrates the use of simulation during the various stages of development of the Morecambe and Rough gas fields by British Gas.
Geomorphological investigation, for engineering purposes, of blowing sand and dust hazard
Authors: Jones D. K. C. , Cooke R. U. , Warren A.
Published: November 2007

Blowing sand and dust are increasingly common hazards associated with dryland urbanization, largely because of the disruption of desert soils by human activity. This paper reviews the characteristics and problems of moving sand and dust and discusses how the four main methods of analysis—remotely sensed imagery, meteorological data, geomorphological mapping and process monitoring—can be integrated so as to provide the basis for well informed management strategies. This is exemplified by description of a recent survey for a town referred to as ‘Alfa’, which involved an unusual methodology heavily dependent on the collection of information on ground conditions by means of geomorphological mapping. The resultant integration of data on erodibility (sand and dust supply potentials) and erosivity (potentials for wind transport using meterological records) provided a good framework for focusing attention on those topographic/sediment units posing the greatest potential hazard and therefore requiring the most careful management. The new methodologies put forward in this paper are considered to be potentially applicable in a wide variety of dryland environments and to be worthy of further development and refinement.
A geotechnical investigation of two Hampshire Tertiary Sand Beds: are they locked sands?
Authors: Barton M. E. , Palmer S. N. , Wong Y. L.
Published: November 2007

The term ‘locked sand’ has been introduced by Dusseault & Morgenstern to distinguish the characteristics of certain, geologically old, natural sands from recently deposited and compacted sands. They examined three North American Sands in detail and described their main characteristics. The work described here is a similar investigation of two English Tertiary Sands to discover whether or not they have similar characteristics. It is shown that the Bagshot and Barton Sands correspond in respect of lack of a cement, an
in situ
relative density greater than 100% and the ability to be sampled as intact, undisturbed blocks. They are, however, slightly less dense and notably less strong than the North American Sands described by Dusseault & Morgenstern. It is concluded that the two English Tertiary Sands are most appropriately classified as
partially or weakly locked sands
.
Data management in engineering geology
Authors: Herbert S. M.
Published: November 2007

D. N. Holt, Chairman of the Engineering Group, welcomed the audience and invited C. Craig of Soil Mechanics Limited to introduce the subject of the meeting.
Book reviews BromheadE. N.The Stability of SlopesSurrey University PressLondon1986£40.00373
Authors: Little A. L.
Published: November 2007

The introduction to this useful book starts by discussing classifications of falls, slide and flows, going on to a brief history, mentioning important historical personalities and events, such as Collin, Hutton Gregory, Gothernburg harbour quay wall and Fort Peck dam failures and the roles of Terzaghi and Skempton.

Chapter 2, discussing natural slope failures, contains a notable series of drawings, photographs and analyses of various kinds of slides, including such classics as Herne Bay cliffs, South Wales valley landslides and the Black Venn mudslides.

Fundamental properties of soils and rocks are discussed in Chapter 3, where concepts of
effective stress
and of
residual strength
are introduced and the importance of
discontinuities
discussed. In Chapter 4, discussion on measurement of shear strength, ring shear testing is emphasized; other methods of testing are also discussed.

Principles of stability analysis (Chapter 5) begins with a consideration of the φ = 0 (total stress) method of analysis, although the author has previously (p. 71) mentioned the difficulties and limitations of this method; the bulk of the discussion is about various methods using effective stress parameters. The discussion continues in Chapter 6 where the use of computers, with detailed examples, and stability charts is discussed.

Detailed consideration is given in Chapter 7 to seepage and pore water pressures where examples are, among others, taken from Cow Green, Balderhead and Tarbela dams, as well as natural slopes at Herne Bay and the Isle of Sheppey. Chapter 8 concentrates on remedial measures, including ground anchors, drainage (both
The effect of weathering on the strength of London Clay
Authors: Chandler R. J. , Apted J. P.
Published: November 2007

A detailed study is presented of the effect of weathering on the undrained and effective stress strengths of London Clay from a site at South Ockendon, Essex. A limited investigation of the chemistry and clay mineralogy was also carried out.

It is concluded that the effect of weathering is to reduce the apparent degree of overconsolidation. This effect is seen in the undrained strength-water content relationship of the most weathered clay, which shows a 4% higher water content at a given strength than the unweathered clay. There is a corresponding reduction of the overconsolidation ratio from about 40 to about 20. In effective stress terms the corresponding strength change is given by a reduction of
c
′ from 28 kPa to a minimum value of about 9 kPa, assuming that ø′ (= 20°) remains unchanged by the weathering.
The use of geophysical methods to locate joints in underground metal pipelines
Authors: Sowerbutts W. T. C.
Published: November 2007

Detailed magnetic surveys have been made to see if the form of magnetic anomalies produced by buried metal pipelines can be used to predict the position of joints between individual sections of pipe. This information can help minimize the amount of excavation required when pipelines have to be examined. Magnetic measurements have been made over pipelines where the position of joints is known, others where their position is unknown, and over a range of types and sizes of pipe with either spigot and socket or welded joints. It is shown that in open country the magnetic anomalies over pipelines consist of a sequence of magnetic highs and lows. This pattern is related to the individual sections of pipe from which the pipelines are constructed, and can be used to determine the position of joints between pipe sections. This method of joint location has been unsuccessful in urban areas due to the presence of other disturbing magnetic anomalies, and the sections of pipe not being uniformly magnetized.
Studies into the design of tubewells in Bangladesh
Authors: Herbert R.
Published: November 2007

The British Geological Survey have carried out a study to determine the optimum design for 2-cusec irrigation wells in Bangladesh. This wide ranging study has included field studies, laboratory measurements, computer simulations and economic comparisons.

One of the aims of well design is to ensure that water is delivered to the irrigator as cheaply as possible. The cost of water is dependent both on the capital cost of the well (well materials, drilling costs, pump installation, etc.) and on recurrent pumping costs. A large diameter, initially more costly, well will reduce well losses and long term pumping costs so there is a fine balance to be struck between capital and running costs if the optimum well design is to be selected. Well-running costs are closely linked to well discharge and drawdown. To date, no accurate method exists of predicting these factors, so well design has been, to a large extent, based on experience.

A number of irrigation wells of different designs have been constructed in Bangladesh and pump tested: both long-term and step-drawdown tests have been employed and, in addition to drawdowns, flow rates within the wells were monitored. Figure 1 shows one of the wells being tested and Fig. 2 shows the results of one step-drawdown test.

The hydraulic characteristics of over thirty types of well screen, with diameters ranging from 4 to 12 inches, have been measured in a specially designed test rig which was constructed at Hydraulics Research Limited for the British Geological
Borehole restoration methods and their evaluation by step-drawdown tests: the case history of a detailed study in Northern Italy
Authors: Clark L. , Radini M. , Bison P. L.
Published: November 2007

The effectiveness of borehole restoration techniques on recharge boreholes has been assessed by repetitive step-drawdown tests. The step-drawdown tests were run with up to 10 steps and repeated up to five times on a single borehole.

The borehole restorations after well-clogging by recharge show that the chemical methods of acidization and polyphosphate dispersion are more effective than physical methods such as surging by pumping.

The step-drawdown test analyses confirm that the squared relationship in the ‘well loss’ in the Jacob equation is valid in uniform aquifers where the total drawdown is a small proportion of the saturated thickness. They also show quite clearly that the so-called ‘aquifer loss’ in the Jacob equation can include large elements of ‘well loss’ indicating that the exact meaning of this equation needs re-examining.
The collection and use of field discontinuity data in rock slope design
Authors: Matheson G. D.
Published: November 2007

The paper highlights aspects important in the collection of field discontinuity data, reviews existing manual and computer-assisted stereographic methods of presenting and evaluating the field data for rock slope design, and describes a new computer method not based on stereographic projection. The new method uses sensitivity histograms to allow evaluation of failure potential and permits the effects of altering design parameters to be readily understood by engineers; it is also particularly good at handling weighted data. The method is, however, intended as an aid to presentation rather than as a replacement of existing stereographic methods as used by engineering geologists.
Injected marl seams as drilling artefacts in chalk cores
Authors: Hilbrecht H. , Meyer T.
Published: November 2007

Marl seams which were injected into chalk cores by the drilling process are described. These artificial marl layers resemble thin debris flow deposits and may be falsely identified. Their diagnostic characteristics are described in order to distinguish them from sedimentary marl seams. In the cored section studied about 400f the total number of marl seams are injected and thus are artefacts.
The formation of pockmarks and their potential influence on offshore construction
Authors: Hovland M.
Published: November 2007

Pockmarks are craters formed in the soft seabed by gas and, in some cases, liquid expulsion. They were described on the Scotian Shelf in 1970
(King & MacLean 1970)
and have since been mapped in a range of shallow seas including the North Sea and the Arabian Gulf.
Pockmarks range in size from less than one metre to about 200 m across and up to 20 m deep.

There are assumed to be three phases of pockmark development:

the pressure build-up phase, in which gas accumulates below the seabed;

the eruption phase when liquids and solids are ejected into the water column;

the post-eruption phase, which can either be a dormant phase or one where gas is continually seeping through the pockmark floor.

The paper discusses triggering of pockmark eruptions which may be by earthquakes, by seabed pressure perturbations caused by tidal or gravity waves or, in deep water, by a combination of tidal waves and low atmospheric pressure and storm waves. The relevance of pockmarks in relation to seabed construction sites is also considered.
Groundwater near the Moray Firth: the coastal aquifer between Forres and Elgin, Grampian Region
Authors: Robins N. S. , Cook J. M. , Miles D. L.
Published: November 2007

Old Red Sandstone, Permian, Triassic and Quaternary deposits form a coastal aquifer to the south of the Moray Firth between Elgin and Forres. Evidence from exploratory drilling, borehole geophysics and hydrogeochemistry show that the aquifer is a complex layered system containing young slightly mineralized water in cracks and joints, older more mineralized water in intergranular storage and mineralized water confined at depth by clay horizons.
Stress-strain behaviour of sulphur concrete made with different aggregates and admixtures
Authors: Czarnecki B. , Gillott J. E.
Published: November 2007

Sulphur concrete is a strong but brittle material. Concrete with a higher sulphur binder content is weaker but more flexible than concrete with a smaller content of binder. Sulphur concrete has unique properties, such as rapid strength development, high ultimate strength, low permeability and superior resistance to strong acids and saline solutions. It has a wide range of potential engineering applications, particularly in situations where problems are encountered in the use of portland cement concrete. Sometimes, sulphur concrete shows poor durability, which may result from expansion and cracking on exposure to water, a behaviour that has been found to result from the use of certain types of aggregates. Admixtures have been found which lead to significant improvements in the strength and durability characteristics of sulphur concretes.

Sulphur concrete was made with seven types of rock as aggregate: granite, syenite, diorite, basalt, greywacke, quartzite and marble. Mixes were made with 20% and 230f sulphur binder and with and without admixtures. Admixtures used were crude oil, glycerine and two types of silane surface active agents. When crude oil was included in the mix, strength decreased significantly but ductility increased. When the aggregate was pre-treated with glycerine the strength of the concrete was affected only slightly but flexibility increased. With silane type A treatment to the aggregate the sulphur concrete had good strength and greater strain capacity than the control mixes made with no admixture. When the aggregate was treated with silane type Z the concrete was very strong but brittle. Treatment of the aggregates with glycerine and the two varieties of silane improved the moisture durability of the sulphur concrete. A comparison of the static and dynamic moduli showed that the three types of sulphur concrete which were more ductile behave similarly to portland cement concrete in that the dynamic modulus was larger than the static modulus. In the stiff and brittle sulphur concretes, that relationship was reversed.
Selecting the location, and the initial investigation of the SERC soft clay test bed site
Authors: Hawkins A. B. , Larnach W. J. , Lloyd I. M. , Nash D. F. T.
Published: November 2007

The Science and Engineering Research Council recognized the need for a soft clay test bed site in Britain. The agreed specification was for a site of at least five hectares of normally consolidated material with a plasticity index greater than 20% and a thickness greater than 10 m. The paper describes the philosophy behind the selection process and details the feasibility studies undertaken at Brean and Newport on the Severn Estuary, Swale on the Thames Estuary and Bothkennar on the Forth Estuary. As a result of these investigations the Bothkennar site was chosen. The consistency of the Carse Clay deposits in the Forth Estuary is shown to be related to the similar rates of eustatic and isostatic rise in that area between about 8500 and 6500 years BP. The southeast corner of the site has more silt-rich/laminated material, believed to be related to a meander infill. The site level is slightly lower than the immediate hinterland, suggesting the effects of isostatic uplift have been compounded by flood tide erosion, which it is believed has removed the upper part of the original Carse Clay deposits.
Estimation of the groundwater resources of the Berkshire Downs supported by mathematical modeling
Authors: Rushton K. R. , Connorton B. J. , Tomlinson L. M.
Published: November 2007

This paper describes a study of the Chalk aquifer of the Berkshire Downs. Extensive fieldwork provided sufficient information for the development of a mathematical model of the aquifer system. Particular emphasis was placed on the representation of the variation of changing transmissivity with saturated depth and the simulation of streams and rivers; flows from the Chalk to the Upper Greensand were also found to be important in certain locations. Comparisons between field and modelled values of both groundwater flow and groundwater head showed good agreement. The model was then used for predictive purposes with particular emphasis on the use of groundwater for river augmentation.
In-field entry of geotechnical data in borehole logging to a hand-held portable computer system
Authors: Ward C. R. , Damtoro J.
Published: November 2007

A series of BASIC programs is described to allow entry, validation and checking of coded lithological descriptions, additional prose-form notes and quantitative geotechnical data to a hand-held portable computer during on-site logging of geological drill holes for engineering purposes. The programs also permit the production of a written borehole log, in the field if necessary, along with tabulations of geotechnical data and a comprehensive graphic representation of the drill hole. Use of such a system avoids some of the errors that may arise in procedures which involve transcription from written notes in a later keypunch operation. The information can be transferred from the portable unit to an office-based facility, when required, for further processing by a more comprehensive installation.
Susceptibility of Coal Measures mudstone to slurrying during tunnelling
Authors: Varley P. M.
Published: November 2007

X-ray diffraction was used to determine the mineralogy of the Carboniferous mudstone rocks on a major tunnelling project in Sheffield. These data were compared to the rock's potential to breakdown, using the slake durability and the Duncan free swelling tests. The limitations of each test are discussed. Particular attention is paid to the effects of weathering, strength and time on the test data. Two comparative indices are proposed for the determination of a mudrock's potential to form a slurried spoil under mechanical excavation.
A site selection case study using terrain analysis in conjunction with an evaluation matrix
Authors: Broster B. E. , Bruce I. G.
Published: November 2007

Air photo interpretation (API) has long been recognized as a fundamental procedure for classifying surficial (superficial) materials in the reconnaissance stage of site evaluation. The results from an API study can help with the rapid assessment of the relative suitability of sites for development and hence reduce costly field work. This paper presents a case history which uses the comprehensive ELUC terrain classification system and API to define the geological framework for seven potential industrial sites. Prior to field investigations the sites were ranked for their suitability using an evaluation matrix. Engineering factors were subjectively quantified relative to geotechnical considerations and entered in the evaluation matrix. This enabled sites to be ranked so that subsequent ground exploration could be concentrated on the most suitable sites. The successful application of the method suggests that it can be used elsewhere as a cost-effective procedure for engineering terrain assessment in the process of site selection.
Swell behaviour of arid climate shales from Saudi Arabia
Authors: Orhan Erol A. , Dhowian Abdulmohsin
Published: November 2007

Arid and hot climatic conditions influence the development of surficial (superficial) sediments by aggravating the desiccation and weathering processes. Such environmental factors promote the occurrence of expansive soils in the Middle East. This study deals with the nature and extent of expansive soil problems in major development areas of Saudi Arabia where severe damage has been experienced in numerous projects. The expansive soils primarily consist of shales of Tertiary age which occur in a narrow strip adjacent to the western boundary of the Arabian Shield. Profile characteristics, geotechnical properties and swell behaviour of the shales are presented. Model equations were developed by nonlinear regression analysis for prediction of swell parameters from easily determined geotechnical indices.
Land subsidence in the AI-Dahr residential area in Kuwait: a case history study
Authors: AI-Rifaiy I. A.
Published: November 2007

Four cylindrical sinkholes occurred between April 1988 and June 1989 in a residential area located 27 km south of Kuwait City. The physiographic and geological conditions of their development and the methods of survey followed to detect potential subsurface cavities in the area are discussed. The major sinkhole is 15 m in diameter and 31 m deep; the others are a few metres in size. A mechanism of migrating sinkholes is suggested, where the upper elastic sediments have been moved down into cavities of the underlying Dammam Limestone. Such movement could have been triggered by garden irrigation and urbanization. A conceptual model is introduced to explain the mechanism of this subsidence. Microgravity techniques were applied using a La Coste Model-D gravimeter to detect areas of subsurface weakness. Negative anomalies in the order of 80 microgals were recorded and considered to indicate underground cavities or zones of contrasted mass-deficiencies representing high risk areas. Moderate anomalies were also recorded and attributed to poor compaction of the ground prior to construction.
Continuous loading oedometer testing of soils
Authors: Davison L. R. , Atkinson J. H.
Published: November 2007

The conventional oedometer test specified in BS 1377: 1975, in which the loads are applied in increments, is simple and robust, but provides relatively little data on the compression and consolidation parameters of the soil or on its preconsolidation or yield pressure. Continuous loading oedometer tests are capable of measuring continuous variations of compression and consolidation parameters and can often identify the yield pressure more precisely. Data logging and control systems developed for stress path testing systems have been applied to oedometer tests and it is now possible to carry out continuous loading tests routinely. Analysis of the test data is relatively straightforward. Tests on reconstituted soil samples demonstrate that the measured parameters do not depend significantly on the type of test.
The influence of changing groundwater levels on the geotechnical behaviour of desert sands
Authors: Al-Sanad H. A. , Shaqour F. M. , Hencher S. R. , Lumsden A. C.
Published: November 2007

The salt-cemented soils which occur at shallow depths in Kuwait owe much of their shear strength to their cementation and tests on natural and artificially cemented sands show that considerable loss of strength may result from soaking and throughflow of fresh water. The evidence that groundwater is rising in Kuwait due to leaking services and over-irrigation in the expanding urban areas therefore has major implications for the future integrity of structures.
Geomaterials
Authors: Fookes P. G.
Published: November 2007

Definitions of geomaterials and related topics are given and inter-relationships between geomaterials and engineering activities discussed in relation to practice.

Weathering of rock mass material in geological time can have a direct and important influence on the durability of aggregate or construction stone in engineering time. Also the production processes in construction procedures can have an important influence on the mechanical strength of geomaterials. Durability, i.e. the rock's ability to resist degradation during its working life, is dependent on a number of important parameters; the original stage of weathering of the rock mass, the degree of imposed stresses during winning, production, placing and in service, as well as future climatic, topographic and hydrological environments. No one engineering test can be used as an absolute predictor of potential durability but a combination of engineering tests, such as water absorption, specific gravity, point load strength, modified AIV and magnesium sulphate soundness, provide the most reliable indicator of durability.
Rock quality in coastal engineering
Authors: Poole A. B.
Published: November 2007

The majority of coastal and shoreline defence structures use large quantities of rock in their construction which will be subjected to environmental conditions quite different from rock used for other purposes. Such materials are required to conform to specific size, shape and grading criteria by the designers of coastal defence structures and rock properties such as density will also be required for the design equations. The severity of the marine environmental conditions will also necessitate adequate levels of strength, abrasion resistance and durability.

A quality assurance scheme for marine structures must take account of all these requirements. Test evaluations must be carried out at an early stage in the design process when alternative materials are being compared and again at the quality control stage of extraction as well as during the construction. Tests can be divided into four groups: those concerned with the geometric properties such as size, shape and grading; those concerned with intact rock strength and resistance to abrasion; with the intrinsic properties of the rock; and those related to durability characteristics such as weathering degradation.

Many of the tests used to evaluate these properties were originally designed for aggregate materials, but recently two tests have been developed specifically for rock to be used in coastal defence structures. These procedures attempt to test those characteristics of the rock materials most affected by the degradation processes found in the marine environment and to offer a method of predicting the in-service performance of the rock with time.