bluuebunny/crossref_metadata_2025 huggingface dataset:
Engineering properties, groundwater conditions, and the nature of soil movement on a solifluction slope in North Norway
Authors: Harris Charles
Published: November 2007

Solifluction during the spring thaw was observed on a till slope of between 5° and 14° in the Okstindan Mountains, Norway. Stability analysis suggested that on the lower slope angles considerable artesian pore pressures would be necessary for failure by sliding to occur, but that on the 14° slope pore pressures only slightly higher than hydrostatic could generate shearing within the soil. However, excavation of a buried plastic tube in the 14° slope section revealed that over a five-year period no shear planes had developed in the soil, soil displacement decreasing gradually with depth and dying out at a depth of 500 mm below the surface. A total surface movement of 82 mm had occurred over the five year period. It was concluded that movement took place as a result of frost creep enhanced by short-term localized liquefaction at the thaw plane as the water-saturated soil resettled to fill the voids left by melting ice lenses. With the clearance of ground ice from the slope, drainage was no longer impeded, and the soil became freely draining and stable.
Investigating old dams
Authors: Little A. L
Published: November 2007

Examples are given of three dams, two rather old, water impounding dams, the other, more recently constructed, for retaining industrial waste. All three dams suffered some degree of failure and, as a result, were investigated more fully than would otherwise have been the case.

At Lluest Wen, following emergency grouting and other work, a detailed examination disclosed so many imperfections in the puddle core that a new slurry trench cut off was provided. A 20 ft diameter shaft at the draw-off works was partly investigatory, partly for remedial works.

The industrial waste dam developed alarming symptoms during its construction and suffered a partial failure. Following investigations, remedial works were put in hand. Even during the progress of these, there were further untoward events but finally, the dam was stabilized.

Tittesworth dam suffered a downstream slide during works to raise the impounding level. The original site investigation failed to find foundation weaknesses which were not fully disclosed until excavations were made during the course of the reconstruction. A search of the owner's records showed that the slope had slipped during the original construction.
Discussion by D. H. L. Keeble
Authors: Keeble D. H. L.
Published: November 2007

There are a number of factors to be considered when deciding the position of a road, such as:

(a)

The position of towns and villages

(b)

The positions of rivers

(c)

The positions of passes in mountains

(d)

The positions of flood plains

(e)

The position of material required for the construc ion of the road.

(f)

The position of materials likely to give future rouble, such as highly expansive clays, collapsing ands, deleterious salts, wind blown sand belts.

Faced with all these factors it is a problem to decide exactly where the road ought to go. As far as Saudi Arabia is concerned, the main factors are:

(i)

The positions of towns and villages

(ii)

The position of sand dune belts-these vary very much in width and height and if possible the narrowest and least high should be chosen so that the road can pass over the sand dunes at the specified grade without having to cut into them or disturb them unduly.

(iii)

Mountain passes and escarpments.

(iv)

Flood plains which may contain deleterious salts.

(v)

The position of construction materials, particularly rock which can be crushed either for concrete or for use as a base material with or without bitumen.

(vi)

The availability of potable water for use in concrete. n considering all these factors aerial photographs are of immense importance, but they are not always available at the reconnaissance phase, so that the selection of alternative routes for detailed consideration
Geotechnical properties and behaviour of some stabilized Nigerian lateritic soils
Authors: Ola S. A.
Published: November 2007

This paper is the final of a series concerned with work conducted at the Ahmadu Bello University on lateritic soils. It summarizes the properties of cement, lime and bitumen stabilized lateritic soils and makes recommendations for field trials. For road construction, the recommended percentages of cement are 3 percent for A1 and A2 soils; 5 percent for A4 soils and 7 percent for A6 and A7 soils. Only A2 soils are recommended for stabilization with lime as base materials and a minimum of 6 percent lime should be utilized for field trial. Bituminous stabilization should be used for the sub-base course only on lightly trafficked roads. The recommended soils are A1, A2 and A3; and 2 to 4 percent of bitumen is recommended for field trial in the first instance.

Soil cement stabilization for low cost one storey buildings is advocated. 5 percent cement content is recommended in the first instance but this could be reduced depending on laboratory results. Reasons for the better success of cement stabilization with lateritic soils are discussed.
The hydrogeology of the Magnesian Limestones in Yorkshire between the River Wharfe and the River Aire
Authors: Aldrick R. J.
Published: November 2007

This paper is a preliminary report on the hydrogeology of the Magnesian Limestones in Yorkshire, between the River Wharfe and the River Aire. Information has been collected in a desk study and a limited field exercise. Although overall abstraction from the aquifer is only 15 percent of the estimated average annual recharge, the concentration of several major abstractions in the Tadcaster area was a cause of concern. As a result of this investigation, groundwater movement within the two limestone aquifers is better understood, particularly the importance of the influence of faulting on groundwater movement and borehole yields.
Discussion on ‘Threshold Slopes in south Wales’ by W. C. Rouse & Y. I. Farhan
Authors: Gray R. A. , Gardner G. D.
Published: November 2007

The authors present an interesting account of the role of rapid mass movements in the slope morphology of South Wales. They attribute much of the slope form to mass movements during periglacial conditions, with more recent movements only superficially modifying that form. A similar conclusion regarding the role of periglacial conditions was made for colluvial masses in the Appalachian Plateau province of the United States (Gray
et al
. 1978, D'Appolonia
et al
. 1967, Philbrick 1961). However, large-scale movement of the type previously assigned to periglacial conditions recently occurred in a colluvial mass in that region, indicating that such movements may not be strictly related to past climatic conditions.

Detailed study indicated that movements may have been triggered by a period of abnormally high precipitation that was preceded by at least 30 years of low precipitation (Gray & Gardner 1977). Large-scale movements are thought to occur infrequently and long intervals may occur where only smaller scale, superficial mass movements occur, such as those now observed in South Wales. Intervals between large-scale movements are marked by continued build-up of colluvium and decreased equilibrium in portions of the larger mass. Eventually, some triggering mechanism (e.g. high precipitation) initiates large-scale movements that continue until the mass reaches equilibrium.

We suggest that a similar mechanism should be investigated for slope development in South Wales. This possibility seems to be supported by the authors' statement that ‘rapid mass movements may be on the increase’.
The engineering petrography of a weathered granite in Cornwall, England
Authors: Irfan T. Y. , Dearman W. R.
Published: November 2007

Five stages and three substages of weathering of rock material have been recognized in the granite from Hingston Down, east Cornwall, England. Changes involved in the seven stages have been characterized quantitatively by petrographic modal analysis of thin slices of the rock and determination of a micropetrographic index

I
p

. A second quantitative index is the microfracture index,

I
ft

.

Mass weathering grades may be characterized in terms of petrological changes in granite materials comprising each grade, and may be quantified in terms of the various micro-petrographical indices.
Large landslides in London Clay at Herne Bay, Kent
Authors: Bromhead E. N.
Published: November 2007

Stability analyses of three large coastal landslides in the London Clay cliffs east of Herne Bay in Kent are presented together with summarised accounts of the investigations which made them possible. The results of these analyses are then compared with the results from other field and laboratory studies of residual strength and slope stability in London Clay.
Economic design of wells
Authors: Stoner R. F. , Milne D. M. , Lund P. J.
Published: November 2007

The cost of water from a well depends upon the capital invested and the annual recurring costs. A large part of the recurring element derives from the cost of pumping. Capital costs and pumping costs are interdependent to the degree that the design of the well affects the drawdown and thus the pumping cost. For example, a short screen section will produce a larger drawdown than a long screen for a given discharge. Thus saving in capital is offset by increased pumping costs. Similarly a screen of small diameter produces large entry and upflow losses and again increased recurring costs. For each chosen design parameter there is an optimum solution for least cost. This paper is concerned with the determination of such least cost solutions.

The principle of the analysis is to produce an equation representing the total cost in terms of a single design parameter and to apply a discounted cash flow procedure to calculate the present value. Differentiation of the present value expression with respect to the chosen design parameter leads to the determination of the optimum value of that parameter for minimum cost.

The analysis depends on certain theoretical or empirical correlations between the parameters involved. These are presented in the paper. A simplified case involving screen length and well depth is discussed in some detail to illustrate the approach. This is followed by a discussion of more complex problems that require analysis by computer.

Determination of the optimum diameter of a well is reviewed in relation to the different components causing well losses. Well losses in very deep wells are examined together with the optimum discharge and diameter of such wells.
Locked sands
Authors: Dusseault M. B. , Morgenstern N. R.
Published: November 2007

A new group of engineering materials, called
locked sands,
has been identified and described. The criteria which differentiate locked sands from dense sands and sandstones are: absence of cohesion, highly quartzose mineralogy, high strength, steeply curved failure envelopes, low porosities, and considerable geological age. Locked sands are also characterized by a lack of interstitial cement, brittle behaviour, residual shear strengths of 30°–35°, and exceptionally large dilation rates at failure. These materials may be common in non-metamorphosed sedimentary strata.

The locked sands were identified during strength testing of Athabasca Oil Sands, a quartzose sand with interstitial bitumen. The St. Peter Sandstone in Minneapolis, Minnesota and the Swan River Sandstone from Manitoba were also found to be locked sands. Tests on artificial dense sands and on redensified material indicate that
in situ
densities cannot be reproduced in the laboratory. The characteristic behaviour of locked sands is the result of dilation, and the dilation is the result of an interpenetrative fabric identifiable by microscopic examination. This fabric and grain-surface rugosity develop through the action of diagenetic processes of crystal overgrowth and solution.
The analysis and planning of step drawdown tests: a clarification
Authors: Clarke L.
Published: November 2007

I have received letters from Mr D. M. Milne and Dr P. F. Worthington pointing out an error in the application of the analytical methods in this paper, (published in 1977 in
Q. Jl Engng Geol
.
12
, 125–143). I would therefore like to take this opportunity to clarify the matter.

The source of the error lies in the use of mixed time-units in the evaluation of the storage coefficient S. Time is given in minutes while the discharge rates are given in m3/day throughout the paper. These units, if applied consistently throughout an analysis, will give correct values for the various well-loss equations and the aquifer transmissivity. The value of the storage coefficient, however, will be 1440 times too great.

The storage coefficient is obtained (p. 139) by the evaluation of the equation:

The discharge rates used in obtaining
a
and T in this equation are expressed in m
3
/day. However,
a
is derived through Figs. 4 and 5 using the specific drawdown at unit time, t = 1 minute, in order to remove the expression (
b
log
t
) from (
a
+
b
log
t
) (p. 132). The units in this equation above have to be made consis-
tent with this derivation and the equation therefore becomes:

where 1440 = number of minutes in one day.

This procedure was carried out in the original paper in order to get the storage coefficient in Table 2 but was not adequately explained in the text.

It is possible to remove the source of
Application of the thermal infra-red linescanning technique to engineering geological mapping in South Africa
Authors: Warwick D. , Hartopp P. G. , Viljoen R. P.
Published: November 2007

The thermal infra-red linescanning technique which is dependent on the radiant temperature and emissivity of rocks and soil has been used increasingly over the past two years for engineering geological purposes. A description is given of the fundamentals of the technique and the equipment used in South Africa as well as the approximate cost. The main engineering geological application has been the mapping of proposed tailings dam sites on dolomites and gabbros in the Western Transvaal. Other applications of the technique are also discussed.

In the case histories considered, interpretation of the thermal infra-red linescanning imagery, as well as air photo interpretation, was also carried out and it is felt that both techniques should be used together for the best results.

The merits and limitations of thermal infra-red linescanning as applied to engineering geological mapping to date is considered and its potential use in other engineering geological applications is discussed. It is concluded that conditions are ideal for the use of the technique where the thickness of soil cover is relatively thin over most of the area mapped. It is also concluded that interpretative methods should be developed further in order that more complete use may be made of thermal infra-red linescanning for engineering geological mapping in South Africa.
Discussion
Authors: Pitts A.
Published: November 2007

The recent landslipping in the Lyme Regis area has, as Mr Conway indicates, related to reactivation of reconstituted and ‘brecciated’ Lias (Lias Head) and Upper Greensand (Cretaceous Head) (Conway, this issue). This is exemplified by the current slippage of East Cliff, and that adjacent to Cobb Road in March 1977. However, not all the movements in the area are of this type, and I would like to present a short case study of a different kind of slip and to comment on the present situation at that site.

On 12 February 1962, the area of Lyme Regis now occupied by Lister Gardens, near the Cobb, slipped, severely damaging a number of properties including Cliff Cottage and Cliff House (Fig. 1). Regrading of the slope had been under-taken with a view to developing the site (Anon. 1962) and may have led to local oversteepening of the slope. Movement took place a few days after the completion of regrading work, with a large tension crack and subsequently a back scar developing in the slope (Fig. 2). A length of slope (almost 200 m) parallel to Marine Parade was affected.

A programme of remedial works was carried out, consisting of drainage and regrading of the slipped area of the slope, the construction of a large retaining structure at the toe (which now houses a parade of shops and part of the promenade), and a small retaining wall at the head of the slipped area. The regraded
Empirical relationship between Los Angeles abrasion and Schmidt hammer strength tests with application to aggregates around Jeddah
Authors: Kazi A. , Al-Mansour Z. R.
Published: November 2007

A study has been made of the Los Angeles abrasion test in relation to the compressive strength of a wide variety of rocks being quarried to meet the growing demand for aggregates around Jeddah. It was found that the results of compressive strength as determined by the Schmidt rebound hammer could be used to predict the Los Angeles abrasion test results.

The aggregates tested are of volcanic and plutonic origins and are basic to acidic in composition. A rock material strength map of the Jeddah area illustrates that most of the coarse-grained plutonic rocks are of low strength and the corresponding Los Angeles abrasion values for these rocks are high, rendering them unsuitable, — especially when the aggregate is to be used in road or building construction or is to be subjected to high wear.
Discussion on ‘Large landslides in London Clay at Herne Bay, Kent’ by E.N. Bromhead
Authors: Dunbaven M.
Published: November 2007

M. D
unbaven
writes: The geometrical forms of the slips described in the paper bear many similarities to failures in mining waste dumps reported by Blight (1969). The important feature of the slides is the coincidence of the lower parts of the slip surfaces with a weaker layer of soil; in this case the Oldhaven Beds of silty fine sand. The example chosen for discussion is the Mirmar landslide where the weak layer forms the base of a simple slope. A careful study of some similar landslides has shown that the graben block and the
en masse
movement of the lower slope are common characteristics.

Recent research at James Cook University has reproduced such failures in a small physical model. A slope made from a well graded cohesionless silica sand was built over a layer of bentonite saturated to give low yield strength. Overall dimensions of the slope were: height 400 mm, width 750 mm, base length 1100 mm. The kinematics of the failure have been determined by photography which revealed basically a movement of two ‘rigid’ wedges.

A computer study based on a wedge analysis was conducted using both force balance and energy balance equations, with the condition that one slip-plane pass through the base material. The situation which created the highest force or energy imbalance was calculated by numerical optimization. For both methods, the predicted slip-planes closely followed those observed in the laboratory, however, different answers would be expected for a material which exhibited significant dilatancy.
Frost heave of roads
Authors: Jones R. H.
Published: November 2007

The mechanism by which frost heave occurs when freezing temperatures, frost-susceptible materials and an adequate supply of water occur simultaneously is outlined. Index tests for identifying frost-susceptible materials (particularly sub-base aggregates) are discussed and emphasis is given to improvements in the Transport and Road Research Laboratory (TRRL) test and the role of suction/permeability relationships.

Analysis of the design procedure to prevent frost heave damage highlights the importance of material and environmental factors. Results from homogeneous and composite specimens support this conclusion. A quantitative model has been developed and reasonable agreement obtained between its predictions and the heave observed in a Precise Freezing Cell. The work described is relevant to the improvement of empirical design procedures in the near future as well as the possible introduction of analytical design methods at a later stage.
The use of a numerical model in the management of the Chalk aquifer in the Upper Thames Basin
Authors: Morel E. H.
Published: November 2007

A non-linear groundwater model has been developed as an aid in the management of the Chalk aquifer in the Upper Thames Basin. The area of investigation includes Stage I of the Thames Groundwater Scheme, and the model has been used to assess the performance of the aquifer during the severe drought of 1975-76 when river flow was augmented by pumping groundwater into the river. Results indicate that the main loss of water during this period was caused by stream-bed leakage and evaporation from the riparian zone, but that these losses were relatively small. The aquifer is shown to have considerable potential for further development as a major source of water, provided that use is made of denser networks of production boreholes located in the middle and lower slopes of the valleys in the area of Chalk outcrop.
Reactions between dolomitic aggregate and alkali pore fluids in concrete
Authors: Poole A. B. , Sotiropoulos P.
Published: November 2007

Carbonate aggregates will react with alkalies from the cement paste in concretes under certain conditions. Several types of reaction are possible, and one involving dolomitic aggregates which contain intergranular clays can lead to disruptive expansion in the concrete. This reaction of dolomite with cement alkalies is essentially one of dedolomitization, a complex reaction rim containing three recognizable zones develops at the interface between the cement paste and aggregate. The details of the reaction processes and of ionic migration with time have been followed using electron probe microanalysis. The effect of the presence of additional alkalies and of sodium chloride on the reaction processes and speed are also discussed on the basis of microanalytical data.
The suitability of aggregates from weathered Peterhead granites
Authors: Moore I. C. , Gribble C. D.
Published: November 2007

Concrete has traditionally been made using sand and gravel filler. Concretes have been compared using two variably weathered granites from north east Scotland as aggregates. This study investigates the differences produced in concrete made from different grades of weathered aggregate.

As the intensity of weathering increases, the bond between mineral grains weakens and therefore the durability of the aggregate is diminished. The intensity of weathering can be shown by the loss of certain oxides in the rock mass.

Some of the major requirements for concretes are the impact and abrasion values of the aggregates used, and the shrinkage and compressive strength of the concrete produced. It can be shown that these values are all dependent on the mineralogy, geochemistry and petrology of the aggregate.
A diffusion exchange model for solute movement in fissured porous rock
Authors: Barker J. A. , Foster S. S. D.
Published: November 2007

A model of solute movement in an idealized, fissured, porous medium, involving diffusion exchange between mobile fissure-water and immobile pore-water, is formulated mathematically and solved numerically for a range of values of the input parameters. The insight gained into this mechanism of solute movement is of relevance in predicting the migration of the more soluble pollutants in the major British aquifers, and is of particular significance to the interpretation of the distribution of tritium and nitrate in the unsaturated zone of the Chalk beneath arable land.
An engineering zoning map of the Permian limestones of NE England
Authors: Dearman W. R. , Coffey J. R.
Published: November 2007

The standard stratigraphical divisions of the Permian limestones of NE England are reviewed and re-interpreted as engineering types in a classification related to engineering geological requirements. Based on this classification a map of engineering geological zonation has been prepared at an original scale of 1:50 000. The general engineering geological characteristics of each zonal unit are described, in relation to engineering construction.
Some preliminary considerations on the selection and durability of rock and concrete materials for breakwaters and coastal protection works
Authors: Fookes P. G. , Poole A. B.
Published: November 2007

The durability of concrete and rock used in marine construction is reviewed. The marine environment has been divided into four significant zones of effect on the durability of concrete and rock. Forms of deterioration specific to concrete or rock and common to both are discussed in the context of the four zones. Rates of concrete deterioration in the zones and in different environments are also discussed.

A preliminary study is presented of the shape, size and weathering characteristics on the performance of rock used in marine structures, particularly rubble-mound breakwaters. Nomographs for field use, relating the design weight of rock to shape, size and specific gravity are presented and acceptance and compliance tests for assessing suitability of rock are suggested. Design of filter systems is also considered in relation to rock characteristics for breakwater cores with high fines contents and for reclaimed areas behind coarsely graded protection works.
Rock slope stability and remedial measures for a residential development at Tsuen Wan, Hong Kong
Authors: Starr D. C. , Stiles A. P. , Nisbet R. M.
Published: November 2007

The Buildings Ordnance Office of the Hong Kong Public Works Department stipulates minimum requirements for site formation plans submitted where rock slopes are involved. In particular, design assumptions and evidence upon which they are based must be clearly stated and verified during excavation by means of engineering geological drawings, showing salient features and details of proposed support and drainage measures.

Examples from rock slope construction records for a residential development at Tsuen Wan, Hong Kong, are presented. The site formation involved excavation of benches into an existing hillside, resulting in the formation of rock faces up to 15 m in height in slightly weathered granodiorite, both beneath and behind the residential blocks.

A rapid system of logging the rock faces by means of subjective surveys using photographic overlays is outlined, and remedial measures employed after final scaling are briefly described.

A potentially unstable rock face was identified at an early stage, and geological conditions are presented in the form of a detailed Face Log. A further investigation of this slope by orientated rotary drilling was carried out, and design parameters are assessed by a combination of back-analysis and laboratory testing. A method of designing active support systems using a computer program is outlined, and ‘as-built’ construction records are presented.
The stability of cuts on the M4 north of Cardiff
Authors: Newbery J. , Baker D. A. B.
Published: November 2007

A case history is presented illustrating the role of engineering geology in the construction N of Cardiff of some 6.6 km of motorway cuttings in glacial moraine and bedrock of Lower Old Red Sandstone age.

The proposed cut at Wenallt, located at the foot of Wenallt Reservoir, had featured prominently in the Public Inquiry. Subsequently this proved to be the only location at which a large failure occurred. Differences between the assumed and actual geological conditions are described. Due to the geological structure and the low residual strengths of c′ = 5 kN/m
2
and ϕ′ = 10.5° in the Devonian marl, the only practical solution involved major earthworks to remove the slipped material. The excavated mass was partially replaced with a toe berm which incorporated a variety of drainage measures.

Experience from this contract has substantiated the need for detailed geotechnical monitoring during construction of major cuts formed in folded and faulted soft rocks. This enables checks to be made on design assumptions, permits revised assessments of stability and facilitates redesign if required.
The assessment of soils and soft rocks for embankment construction
Authors: Parsons A. W.
Published: November 2007

During earthwork construction, the assessment of the quality of the excavated soil to determine its suitability for use as fill requires a rapid, reproducible test, the results of which correlate well with engineering properties. The newly-developed moisture condition test fulfils these requirements.

In the relatively shallow embankments in road construction, the operating ability of earthwork construction plant is frequently used as the criterion of suitability of fill material. Relations have been established, therefore, between factors affecting the productivity of earthmoving plant and the moisture condition value. Furthermore, predictions made at the design stage of a scheme of the potential quantities of available material suitable for use in embankments require a knowledge of the possible effects of weather conditions during the construction period on the condition of the soil. Recent research has set out to determine these effects and their associated impact on the planning of the earthmoving operations.

An earthwork material that can cause particular difficulties during embankment construction is chalk. A classification for chalk has been developed in terms of its saturation moisture content and a chalk crushing value. This indicates, for each class of chalk, the preferred method of working in order to minimize the difficulties.
Introduction Mudrocks of the United Kingdom
Authors: de Frietas M. H.
Published: November 2007

A compendium of the papers read at the Geological Society on 18 September 1981

It is surprising that in the UK, where so much of the ground on which we build originated as muddy sediments, there is no collection of papers readily available for engineers and geologists alike that describes the geological distribution and general character of our mudrocks, their range of properties and the problems associated with defining and predicting their geotechnical behaviour. The one-day meeting was an attempt to fill this gap. It soon became clear, however, that the subject could not be adequately covered in one day, and the meeting was probably the first of what will become a series, over the years, to deal with the subject at large. The scope of this meeting was restricted to the non-calcareous mudrocks, which were taken to include our over-consolidated clays. Calcareous mudrocks, which include many limestones, were not considered. The papers reproduced here are largely a record of the data that were presented at the meeting.

The authors of the papers were asked to provide a review of their particular subject, supported by a selected bibliography that would direct the reader to more detailed information. Many of the papers are, therefore, general in nature and are written for the reader in need of basic information founded upon our knowledge of the subject to date. Twelve papers were read at the meeting and their sequence in this publication reflects the grouping that was used for presentation. The first four papers describe the geographical position and geological nature of the major mudrock deposits in
Mudrocks in the Carboniferous of Britain
Authors: Ramsbottom W. H. C. , Sabine P. A. , Dangerfield J. , Sabine P. W.
Published: November 2007

The distribution of mudrocks in the British Carboniferous is largely related to the underlying block/basin structure, the basins showing mainly muddy sequences. Most mudrocks are in the Upper Carboniferous Coal Measures, where they form more than 500f the sequence. Average chemical analyses and mineralogical compositions of fireclays mainly from the Upper Carboniferous are given and compared with international averages; the Phanerozoic secular variation of CaO/MgO ratios resembles Russian results.
Mineralogy and petrology of the argillaceous sedimentary rocks of the UK.
Authors: Shaw H. F.
Published: November 2007

The non-clay and clay mineralogy of the British argillaceous sedimentary rocks are discussed. The non-clay mineralogy is only considered in general terms due to the lack of detailed information. The general nature of the clay minerals, their genesis and the effects of burial diagenesis on clay minerals are reviewed. This is followed by a more detailed examination of the clay mineralogy of the Palaeozoic, Mesozoic and Tertiary argillaceous rocks. Consideration is given to the relative importance of the depositional environment and burial diagenesis in forming the clay assemblages now found in British mudrocks.

The petrology of the argillaceous sedimentary rocks is discussed in general terms. The use of electron microscopy in the examination of mudrocks generally and some British examples in particular is reviewed, including a discussion of the nature and origin of fissility. The possibility of using high voltage electron microscopy in future studies of argillaceous sediments is proposed based on its successful use in examining the microstructures and mineralogy of slates.
Geomorphological aspects of slopes in mudrocks of the United Kingdom
Authors: Anderson M. G. , Richards K. S.
Published: November 2007

Introduction

A marked convergence of interest has characterized geomorphological and engineering investigations of slopes during the last decade or so. The former have combined traditional geomorphological mapping with recently developed remote sensing methods to identify and classify stable and unstable slopes, while examination of slope-process mechanics and application of stability analyses formulated by engineers have both become important themes (
Prior 1978
). The latter have become increasingly concerned with Quaternary slope evolution, because of the danger of reactivation of fossil mass movements during engineering projects (
Skempton 1976
). However, distinctive elements exist in geomorphological approaches to hillslope studies. Relevant temporal and spatial scales are broader than those of immediate interest to the engineer, and concern with long-term slope development is necessarily paralleled by investigation of regional slope assemblages, through both the interpretation of regional slope angle histograms and the development of models of slope evolution in relation to Quaternary climatic change and general drainage basin processes. Such long-term regional slope development reflects the summation of discrete, local events, making consideration of individual slopes and mass movements also necessary. At this scale, geomorphological interest relates to morphology, the magnitude-frequency properties of different processes, the dating of events, and the environmental controls of slope stabiliity, such as the spatial variation of soil water pressures and weathering. These general approaches are focussed on specific slopes by a geographical appraisal of variation of salient geotechnical properties both between and within particular lithologies, which permits calibration of appropriate stability models in the specific
B. J. Connorton writes
Authors: Morhel E. H.
Published: November 2007

The most important hydrogeological finding to come out of the field investigations carried out during the various phases of test pumping of Stage 1 of the Thames Groundwater Scheme was the realisation that the magnitude of transmissivity (T) and storativity (S) decline significantly with depth (Owen
et al.
1977). Bearing in mind that the purpose of the scheme is to abstract ground-water at times of drought, the main implication of this finding is that aquifer parameters are likely to be appreciably lower under operational conditions than under normal seasonal conditions.

The author employs the Nutbrown inverse method (Nutbrown 1975) to compute the areal distribution of T and S which are then input to the groundwater model. This particular inverse technique is based on a cyclic time integration of the conventional linear groundwater flow equation, consequently, T and S values computed by this method will necessarily correspond to some average seasonal groundwater stage condition.

Morel's ‘non-linear’ model is so called because the transmissivity parameter is represented as:

T = K
a
b (1)

where K
a
= K
a
(
x
,
y
) ... average hydraulic conductivity,

b = b(
x
,
y
, h)... saturated aquifer thickness,

and h = h(
x
,
y
, t) ... groundwater head

K
a
is obtained by dividing the T value computed from the inverse method by 50 m (assumed average aquifer thickness).

Storativity is a function of areal position only as computed by the inverse technique. Essentially, the author is modelling the unconfined Chalk aquifer as though it were a vertically homogenous porous medium. Equation (1)
Hydrogeology of the Kufra and Sirte basins, eastern Libya
Authors: Wright E. P. , Benfield A. C. , Edmunds W. M. , Kitching R.
Published: November 2007

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

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

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

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

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

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

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