bluuebunny/crossref_metadata_2025 huggingface dataset:
Discussion on ‘Land Surface Evaluation for engineering practice’ by a Working Party under the auspices of the Geological Society
Authors: Styles K. A. , Brand E. W. , Burnett A. D.
Published: November 2007

K. A. S
tyles
, E. W. B
rand
and A. D. B
urnett
write: The Working Party Report on Land Surface Evaluation for Engineering Purposes will have been read with great interest by those closely associated with work of a ‘terrain evaluation’ nature. Anyone who has been involved in the writing of a state-of-the-art document will appreciate the amount of time and effort that must have been devoted by the Members of the Working Party to their difficult task, and they are to be congratulated on producing a document which will prove to be useful to the profession. The writers must confess, however, to being disappointed that the Report fails to deal adequately with the terrain interpretation methods used in modern engineering practice. Unlike previous Geological Society working party reports, the document in question does not fully represent the current state of the art, and it therefore falls short of providing the standard source of reference that we have come to expect from the Geological Society.

The main disappointment with the Report stems from the fact that the material on which it is based is somewhat ‘dated’. As a result, it does not fulfil the objective stated in Section 1.2, namely ‘to report on Land Surface Evaluation outlining the state of the art and making recommendations for good engineering practice’. It is noted that the Working Party was set up in 1974, and perhaps the material for much of the Report was assembled soon after that time, for surely the state of the
R. J. G. Edwards replies
Authors: Edwards R. J. G.
Published: November 2007

In their discussion of ‘Land Surface Evaluation for engineering practice’ A Working Party Report (
Q. J. eng. Geol.
15,
265–316)., Messrs Styles, Brand and Burnett have suggested that the report ‘failed to deal adequately with the terrain interpretation methods used in modern engineering practice’; ‘did not represent the state of the art as claimed’; and was outdated as from 1979’. Further, ‘that the working party was unaware of whole areas of documented research’; ‘was parochial’; and ‘could not have achieved its stated objectives without casting a much wider net than it did’.

Such swingeing criticisms are difficult to answer constructively. As the report clearly indicates, the work of the committee was completed in 1978 after some four years of preparatory work. It is regretted that although submitted in late 1978 the report was not published until 1982 for reasons outside the control of the Working Party. The Working Party was aware that the techniques facilitating particular aspects of Land Surface Evaluation were developing at a tremendous pace at this time (as they still are today) and that this explosive growth had far outstripped the ability of any non-funded national organization to collectively evaluate their technical merits. The Working Party's acute awareness that the engineering profession as a whole was still in the process of accepting that these techniques were individually or collectively cost effective, and that Land Surface Evaluation should be regarded as a standard method for geotechnical appraisal, resulted in it being decided and agreed to restrict the Report
Discussion on ‘Comparisons between real and predicted geology in tunnels: examples from recent cases’ by G. West
Authors: Douglas T. H.
Published: November 2007

T. H. D
ouglas
writes: Graham West has provided a useful summary of data obtained from the case studies he has used to illustrate the effectiveness of site investigations for tunnels. However, due no doubt to the limited space allocated within the text of a single paper, there are a number of further comments which should be noted in relation to the comparison between predicted and actual geology of the Diversion Tunnel at Dinorwic.

Construction of the Diversion Tunnel started in November 1975 and was completed in July 1978. Taking into account the final cost and comparing the site investigation costs, updated to the same base date, indicates a figure of 1.4 for the site investigation as a percentage of the capital cost of these work. The figure includes for the special investigations associated with the old copper workings and the cost of additional precautions while tunnelling advanced through the critical zone.

Reference is included in the text to a comparison between predicted and actual lithology—this is shown on fig. 6 and listed in table 3. While the different lithologies were of some interest and the variation in hardness had a slight effect on rates of drilling, the principal influence on rate of advance was the amount of lining required. While a comparison between the amount included in the Bill of Quantities (651 lin. m) to that installed (455 lin. m) may be of interest a further comparison is shown in the Table 1.

It should be noted that the basis
Discussion on ‘Towards the prediction of subsidence risk upon the chalk outcrop’ by C. N. Edmonds
Authors: Wilson E. J.
Published: November 2007

E. J. Wilson write: Figure 1 of Edmonds' paper suggests a geographical distribution of solution features which is highly distinctive yet apparently defies geological or climatological explanation. One is reluctant to accept such distribution as a starting point for the analysis of a problem, unless either it can be explained, or it can be shown that it is not due to any other spurious factor. It is immediately obvious that the lowest density of solution features recorded is for Salisbury Plain, a large proportion of which, as a military training ground, has a land use which would be expected to have a very low sensitivity to solution features. It is also obvious that most areas of high density lie within the Home Counties. This suggests the hypothesis that solution features are more likely to be discovered, and hence to become the subject of available data, in more highly-developed areas.

To put this hypothesis to the test, a comparison was made between population density as shown in the

Ordnance Survey Atlas of Great Britain
, and the density of solution features as shown by Edmonds. A direct and reliable comparison would be difficult, however, without much more detailed analysis, since there is considerable overlap between areas from the two sources. Furthermore, there are many small areas of high population density, but these are mostly concentrated in valley bottoms, which Edmonds' Fig. 2 shows are not a preferred location for solution features; therefore they have been ignored on the basis that they would
The Thames tidal flood risk—the need for the barrier: a review of its design and construction
Authors: Horner R. W.
Published: November 2007

The Thames Barrier is one of the largest civil engineering schemes built in England. It was necessary because of the increasing landward migration of the tidal effect due to eustatic rise and the relative land/sea level changes due to the subsidence of the North Sea area, resulting mainly from post-glacial isostatic effects. This meant that up to 116 km
2
of London could be flooded under a high surge tide.

The nine piers and two abutments were built in coffer dams. Construction began in 1975 and was completed in 1982.
A review of the geotechnical properties of Somerset alluvium using data from the M5 motorway and other sources
Authors: Cook D. A. , Roy M. R.
Published: November 2007

Construction of the M5 Motorway over recent soft clays within the Somerset Levels left behind a legacy of geotechnical information which has been assembled on a computer file containing the findings of 243 borings between Clevedon and Huntsworth. The paper gives examples of the use of the file for production of representative profiles of moisture content, strength, Atterberg limits and compression behaviour. These serve to highlight many of the now familiar characteristics of Somerset Alluvium and similarities with other recent deposits in the U.K. In particular they indicate the variability to be anticipated due to changes in consistency of the material, its sensitivity and some reflection on the method of sampling and testing. The profile of over-consolidation within the zone of desiccation is also clearly seen.

Some tentative correlations are made between Atterberg limits and corresponding measurements of sensitivity, strength and compression constants (C
c
, λ) on the basis of Critical State theory, which serve to show a more consistent and more useful pattern.
Stratigraphy and properties of the Clyde alluvium
Authors: McGown A. , Miller D.
Published: November 2007

The paper outlines the geological history of the Clyde Valley and attempts to relate this to the nature and distribution of the sediments within it. Because of the position of the valley within a glaciated region in which isostatic recovery has occurred, the infill deposits are very complex, with fluvio-glacial, lacustrine, marine, brackish and freshwater deposits overlying glacial and pre-glacial materials. The soils within the succession have been identified, classified in terms of their basic physical properties and their likely engineering behaviours have been indicated. The engineering significance of the nature of the various strata within the stratigraphical sequence is then discussed.
Engineering geological and geophysical investigation of the Barking Creek tidal barrier site
Authors: Kirkpatrick I. M. , McCann D. M.
Published: November 2007

The Barking Creek tidal barrier is downstream of and complementary to the main Thames flood prevention barrier in Woolwich Reach. Preliminary site investigations included boreholes and a ‘sparker’ geophysical survey of the Creekmouth area to determine the geological structure, in particular the depth and attitude of the interface between the Thanet Sand and the Upper Chalk beneath the barrier site. Several subsequent phases of drilling at the site have allowed refinement of the original interpretation, and variations in the levels of the chalk-sand interface previously correlated with east-northeast to west-southwest trending faults are now considered to represent faults trending north-northeast. This direction is consistent with the geological structure in similar rocks determined at the Thames Barrier site 5 km upstream and elsewhere in southern England.
A buried valley in the Orwell estuary
Authors: Fletcher M. S. , Nicholls R. A
Published: November 2007

The investigation of the geology of the River Orwell downstream of Ipswich was carried out by the Department of Transport in the period 1973 to 1978. A buried valley in the surface of the Upper Chalk was identified and defined. The depth of the valley is 45 m below sea level and very soft chalk occurs adjacent to the valley.

The methods used to sample and classify the chalk for engineering foundation design purposes are presented. The infill material to the valley is described and the influence of the valley upon the chalk is indicated.
Engineering solutions to geological problems in the design and construction of Humber Bridge
Authors: Simm K. F.
Published: November 2007

The geology and resultant foundation conditions for the Humber Bridge are described. On the north side the anchorage and pier are founded on Chalk, while on the south side the foundations are on Kimmeridge Clay.
A geological appraisal of the site of the foundation failure of the giant oil tanks at Fawley, Hampshire
Authors: Barton M. E. , Roche M. H.
Published: November 2007

Two giant oil tanks (79.3 m diameter by 19.5 m high) were constructed at Fawley in 1967-68. The tanks were founded on a reinforced concrete slab supported by piles of varying lengths taken through alluvium and end-bearing in Valley Gravel which overlies Barton Clay (Eocene). Totals of 1580 and 1652 piles, respectively, were used for each tank. The foundations failed during water-loading tests with a maximum depression of 0.425 m in one of the reinforced concrete slabs. Post-mortem examination of the foundations revealed defects in a number of piles, and after further tests and investigations, Professor G. A. Leonards concluded that the failure was due to defective piles.

The success of the original design was critically dependent on the geology. Particular problems on which attention was focussed included the continuity and thickness of the gravels, their variation in density, the character of the interface between Valley Gravel and Barton Clay and the lithological variations within the alluvium. These problems are examined here in relation to the existing geological knowledge of the region. Of particular significance is the conclusion that, in part, the variation in density within the gravels is due to the existence of Flandrian gravel overlying Pleistocene terrace gravel. Isopachytes of the gravels have been drawn along with contours on the upper and lower surfaces. These are compared with the settlement contours of the failed foundation slab and it is concluded that there is no correlation between them.
A technical note on the design and construction of the Afon Ganol Valley section of the North Wales Coast Road (A55)
Authors: Arber Neil
Published: November 2007

Introduction

A 2-km length of the North Wales Coast Road (A55) between Colwyn Bay and Conwy runs along the floor of the Afon Ganol Valley which once formed part of the River Conwy estuary (Fig. 1). The road embankment, which in this area varies in height from 2 to 7 m, is constructed over soft alluvial clays and peat, up to 15 m (Fig. 2). The varying ground conditions along the length of the road embankment resulted in two completely different forms of embankment design.

Geology and embankment design

At the western end where the embankment was highest and widest in order to accommodate two slip roads to a low level rotary interchange, the alluvial clay was thickest, but no peat layers were found. Continuous sampling of the alluvium proved it to be a soft grey silty clay in which three main layers were identified, each 4-5 m thick. The upper layer contained near vertical root stems, the middle layer contained fine sand partings and the lower layer was very similar to the upper layer, except it contained small pockets and thin layers of peat. Some partly decomposed wood fragments were also found in the lower layer. A typical plot of the Atterberg limits and bulk density against depth clearly shows the presence of the three layers (Fig. 3).

In this area it was decided to promote primary consolidation using band drains to keep construction time to a minimum and to reduce post-construction settlements. Laboratory consolidation and
in situ
permeability
Geotechnical aspects of Greenodd by-pass
Authors: Thompson R. P.
Published: November 2007

This paper describes the geotechnical aspects of the site investigation and construction of a by-pass to Greenodd Village in the southern part of the Lake District. The proposed route ran along west bank of the River Leven, crossed the main channel of the river and rejoined the existing road south of Greenodd. The investigation revealed that in places deep deposits of soft alluvium existed. Using the field measurements of permeability to determine the rate of consolidation in preference to values measured in the laboratory oedometer tests, it was decided that an embankment could be constructed safely and within a reasonable time. During construction the increase in excess pore pressure was monitored and the rate of filling modified to ensure a minimum factor of safety was achieved.

The project also involved construction of two bridges. From the findings of the site investigation it was decided to adopt pile foundations with the piles being driven steel H piles having an enlarged section set back from the toe. This ensured that the pile reached the required driving set after only a short penetration into the gravel stratum underlying the soft alluvium. Pile tests were carried out on preliminary piles to confirm the adequacy of the design and on works piles to ensure the required load carrying capacity was actually achieved.
Tunnelling through warp: an estuarine clay
Authors: Slocombe R. T.
Published: November 2007

A tunnel was constructed through the soft, silty clay of the estuarine deposits at Grimsby. The 2.6-m tunnel was driven in compressed air at 40-55 kN/m
2
.
Application of aquifer testing to deep shaft investigations
Authors: Daw G. P.
Published: November 2007

Deep lying aquifers are a major hazard in shaft sinking and it is essential to obtain prior knowledge of their location, transmissivity, pressure and nature of porosity in order to assess the potential inflow to the excavated shaft. This helps to determine the most appropriate means of ground treatment to minimize water inflow during the subsequent construction.

Aquifer test methods based on the measurement of the recovery of pressure in a single borehole following a period of controlled flow, such as the petroleum industry ‘drill-stem test’, are generally the most appropriate techniques. Several modifications of the standard drill-stem test are described including a new type of probe-hole test carried out during shaft construction from the advancing excavation face. This test has also been used to assess the effectiveness of a cover grouting operation.
Discussion on ‘Engineering geomorphological investigations of a possible landslide, Killiecrankie Pass, Scotland’ by Robert Chaplow
Authors: Chaplow R.
Published: November 2007

Sir Alexander Gibb & Partners was appointed by the Scottish Development Department in September 1972 to carry out a feasibility study of the possible routes for the Killiecrankie to north of Calvine section of the Perth Inverness Trunk Road Improvements. The original brief only extended to the north end of Killiecrankie Pass but this was extended to cover the section through the Pass in June 1973. The results of the geotechnical study carried out by Allen Gordon & Co., to which Allen refers, were made available to Gibb for use in their report.

Although, as Allen states, the landslide had been identified as part of a much larger feature in 1973, the interpretation was based upon very limited subsurface information. A single rotary borehole had been drilled into the landslide from which no recovery had been obtained down to 4.00 m depth and only partial recovery below this level to the base of the overburden at 9.00 m depth. This borehole had been supplemented by four nearby hand auger holes. The supplementary investigations carried out in 1981 included a series of deep trial pits and trenches into the suspected landslide. These provided data on the nature, structure and geotechnical properties of the soils necessary to arrive at the interpretation presented in the paper.

Design of the road proceeded on the basis that the embankment and cutting solution would be adopted where possible. In general this solution was adopted and the majority of the road including the section across.

In the
Boundary Element Methods in Solid Mechanics by S. L. Crouch and A. M. Starfield CrouchS. L.StarfieldA. M.Boundary Element Methods in Solid MechanicsGeorge Allen & UnwinLondon3220 04 620010 X£20.00 hardback
Authors: Priest S. D
Published: November 2007

Many engineers are familiar with the finite element method, which involves the analysis of the forces and displacements in a network of discrete elements that are designed to represent the mechanical and geometrical properties of the structure being studied. The last decade has seen the emergence of an alternative method; a method that represents a structure not by discrete elements within the material but by elements on the boundary of the material. The acceptance and ultimate popularity of this latter boundary element method depends to a large extent upon the lucidity of texts that seek to explain the method and also upon the availability of computer programs that apply the method. This book, in my opinion, makes an important contribution in both areas.

The authors, who are Professors in the Department of Civil and Mineral Engineering at the University of Minnesota, are well known in the fields of mining engineering and rock mechanics for their papers on the application of boundary element methods in the analysis of stresses and displacements around under-ground excavations. In particular, Professor Crouch has been responsible, perhaps more than anyone else, for the development and application of the displacement discontinuity method.

The first chapter provides a non-mathematical introduction to the boundary element method and gives an explanation of some of the terms used. Chapter 2, which is a review of linear elasticity, contains material that can be found in many standard texts on the theory of elasticity. The inclusion of this material here does serve to
Introduction
Authors: Baxter K. M
Published: November 2007

The International Drinking Water Supply and Sanita-tion Decade has focused the attention of governments and financial donors on meeting the decade targets of providing potable water and adequate sanitation facilities for all by 1990. However, although these issues have received much attention from both engineers and economists, it is still estimated that about 1500 million people do not have access to potable water or basic sanitation. This one-day conference was aimed at re-viewing the level of groundwater development in the Third World and suggesting ways of meeting the decade targets.

The first contribution was from Mr S. M. Niaz of the Agriculture and Rural Development Department of the World Bank in Washington. Mr Niaz was the ‘link-man’ between the financial and technical facets of groundwater development. He outlined the Bank's cycle of project identification, preparation, negotiation, implementation, completion and evaluation. Generally, in World Bank schemes only proven technology is used, although a limited amount of new technology may be included on a trial basis.

Consideration was given next to the difficulties of groundwater assessment in the volcanic-sedimentary environment of Central Java by Dr J. W. Lloyd (University of Birmingham, UK) and others. Lithological inhomogeneity does not allow easy aquifer delineation and also makes the construction of dams to retain the high rainfall difficult. Only major dewatering schemes can substantially add to the groundwater resources of the area and then only after careful long-term planning.

The difficulties of locating groundwater resources in the basement complex areas of Africa were outlined by
International funding of groundwater development schemes
Authors: Niaz Sadiq M.
Published: November 2007

Groundwater is an important source of water for irrigation and as its exploitation has increased tremendously over the last two decades, both through public and private sectors, a number of development schemes have been assisted financially by several international donors, including the World Bank. It has been estimated that the Bank has lent about US $1.4 billion for groundwater development of which about US $450 million has been for projects in the public sector with the remainder going to schemes in the private sector through agricultural credit.

The Bank's project cycle consists of the identification of a scheme, its detailed preparation, its appraisal, an assessment of its economic and financial viability and a review of the institutions involved. Finally, the Bank's Executive Directors will approve the loan subject to the recommendations of the appraisal mission.

The Bank has gained considerable experience in ground-water development schemes through lending, and in countries where suitable resources and institutions exist, the Bank has successfully supported work in both the private and public sectors. In the design of new schemes no undue risks are taken and only proven technology is used; new technology must first be tested on a smaller scale.

Before development of communal schemes it is often vital that a Water Users Group is formed to correctly administer the scheme. In many countries it may also be necessary to establish a legal framework for groundwater use, although it is recognized that there are considerable difficulties in enforcing such laws.

Groundwater schemes financed by credit require careful monitoring and technical support as some borrowers do not fully complete their commitment due to technical or other difficulties. In addition, there should also be some mechanism to assist those borrowers whose investments end in failure. Increased attention should also be given to the operation and maintenance (O&M) of schemes; in particular, borrower governments should be urged to budget for O&M.
The expanding role of the hydrogeologist in the provision of village water supplies: an African perspective
Authors: Grey D. R. C. , Chilton P. J. , Smith-Carington A. K. , Wright E. P.
Published: November 2007

It has generally been assumed that little attention need be given to the design and construction of rural water supply wells as the yield requirements are small and the construction costs low. A different view is presented in this paper, illustrated by examples from several African countries. New thinking is required if limited financial and trained manpower resources are to be used effectively in providing reasonably low-cost but adequate and reliable groundwater supplies. The argument that a substantial hydrogeological input will be expensive is countered by demonstrating that neglect of hydrogeological principles and practices can result in very much higher costs. The need for hydrogeologists and water engineers to be aware of the social and institutional aspects of rural water supply work is stressed.
The problems of groundwater assessment in the volcanic-sedimentary environment of Central Java
Authors: Lloyd J. W. , Pim R. H. , Watkins M. D. , Suwara A.
Published: November 2007

The geology of Central Java can be defined in terms of distance from volcanic centres located along the spine of the island. Coarse ejecta are reworked on the upper volcanic slopes to form a scree, and coarse to medium grade fluviatile sequences slope downwards. At the base, shallow marine sedimentation along a rapidly retreating coast line has created a clay-sand sequence. This variety of depositional facies has produced a lithological inhomogeneity that poses problems of aquifer delineation, and makes the cuttings from direct-flush rotary drilling difficult to interpret. Geophysical logging of the volcanic sediments also presents difficulties as gamma logs lack features because of high background counts so that resistivity logs have to be used to locate well screens.

Unconfined conditions exist on the upper and intermediate slopes of the volcanoes while beneath the lower slopes and coastal plains is an upper unconfined aquifer overlying lower, confined aquifers. Despite geological and hydrogeological inhomogeneity, approximate groundwater head distributions can be reasonably determined in the unconfined areas; multilayering makes this difficult in the confined areas.

Groundwater development for irrigation is seen as a long-term aim in the unconfined areas of the intermediate slopes of the volcanoes. Further groundwater development, by manipulating the aquifers' specific yield and its high potential recharge currently lost to flood flow, appears to be feasible. Accurate assessment of the potential development is difficult due to the complex hydrogeology and extensive existing groundwater use. Development will therefore be slow and require careful planning.
Development of public tubewell designs in Pakistan
Authors: Bakiewicz W. , Milne D. M. , Pattle A. D.
Published: November 2007

Much of Pakistan's 13 million ha of irrigated land is underlain by the Indus River System alluvial complex, which forms a highly transmissive aquifer, often saturated to within a few metres of ground surface. Since the 1960s, public well fields have been installed in this aquifer for water table control and for providing supplementary irrigation water. The early well designs utilized unprotected mild steel components, screens with saw-cut slots and filter packs of ‘pea gravel’. These suffered from a number of drawbacks, including sand pumping and rapid specific capacity deterioration, attributed at the time to corrosion and associated incrustation of the well screens. Design modifications, introducing finer, graded gravel, a more suitable slot size and corrosion resistant materials, resulted in an almost immediate solution of the short-term problems. However, long-term performance monitoring has disclosed slow but serious well deterioration, the causes of which are still not understood. Circumstantial evidence suggests that this deterioration is at least partly due to some chemical mechanism, probably affecting the formation/gravel filter interface. Systematic studies and rehabilitation trials are urgently required to establish effective remedial measures for existing wells and modifications of design for future wells.
The interpretation of slug tests in fissured rocks
Authors: Black John H.
Published: November 2007

Slug tests in fissured low-permeability rocks using small-diameter tubing and straddle packers were analysed according to the conventional homogeneous porous medium analysis of

Cooper
et al.

Because the results cast doubt on the applicability of this conventional slug test analysis, a new fissured porous medium analysis has been devised. Conventional analysis forms a special case of the new analysis. In practice, the new four-parameter (compared to the previous two) analysis is unwieldy and it is considered likely that conventional analysis will continue to be misapplied to fissured rocks.

The new analysis has been used to estimate the errors resulting from the misapplication of the conventional analysis. It is concluded that errors in the values of derived transmissivity are unlikely to exceed a factor of two. In contrast errors in the value of derived specific storage vary from underestimates of 1 × 10
-6
to overestimates of 1 × 10
6
. The new analysis has also been used to reinterpret the original data from tests on fissured low-permeability rocks and a more self-consistent set of results was obtained. A facet of tests in fissured rocks is the common occurrence of interpretations yielding exceptionally low values of specific storage. A table of values to construct type curves to match this sort of test involving very low values of α, a function of groundwater storage, is given as an Appendix.

It is concluded that in slug test analysis it is essential to know what values to expect, especially of specific storage, in order to make correct interpretations.
Some landslipping encountered during construction of the A40 near Monmouth
Authors: Early K. R. , Jordan P. G.
Published: November 2007

The A40 is a trunk road constructed in 1964 on sidelong ground beside the River Wye, about 1.54 km, north of Monmouth. The sidelong ground comprised a dip slope of 30-35° dip in the Brownstones of the Devonian which consist of sandstones with subordinate mudstones. On investigation it was found that three ancient landslips existed which the road had to cross. One, at Chapel Farm, was estimated to be probably first active in post-glacial times; another at Whipping Green, was estimated to have occurred at about Roman times; and the third, at Vaga, was estimated to have occurred sometime betweeen the other two. Conventional engineering had not succeeded in crossing the sidelong ground without re-activating these slides. Total failure had occurred at Chapel Farm Slip and the inter-carriageway slopes had failed where the road crossed Whipping Cross Slip. After a full investigation the road was re-designed more or less on its original route using light-weight fill for embanking and a massive berm at Chapel Farm, and chiefly by using replacement counterforts on the cut slopes at Whipping Green Slip. Sand drains were used through the Wye alluvium below the berm where it was founded over the alluvium. There was also a large area of ‘partly slipped rock’ which although it did not constitute a landslide, threatened the road from above and was far too large and complex a mosaic for treatment or removal. It was decided to build a rock fill revetment at the toe of this mass and then to monitor it for movement on the assumption that only one or possibly two parts of the mosaic could move at any one time. During the investigation a fairly exhaustive laboratory testing programme was carried out and a detailed study was made of the behaviour of groundwater. It is now 1984, some 20 years after construction of this section of road and there has been no trouble of any kind.
The control of wind blown sand and moving dunes: a review of the methods of sand control in deserts, with observations from Saudi Arabia
Authors: Watson A.
Published: November 2007

In desert regions where unconsolidated surface sediments are mobilized by the wind, problems of controlling drifting sand and moving dunes can be severe. In the Eastern Province of Saudi Arabia drift rates reach 30m
3
m width annually and barchan dunes, up to 25 m in height, have an average rate of movement of nearly 15 m per annum.

The problems caused by wind blown sand can be tackled in four ways: (1) by enhancing its deposition, using ditches, fences or tree belts; (2) by enhancing its transport, using streamlining techniques, creating a smooth texture over the land surface, or by erecting panels to deflect the air flow; (3) by reducing the supply of sand upwind, using surface stabilizing techniques, fences or vegetation; (4) by deflecting the moving sand using fences or tree belts.

Moving dunes can be dealt with in three ways: (1) by removing them mechanically; (2) by dissipating them using reshaping, trenching or surface stabilization techniques; (3) by immobilizing them through altering their aerodynamic form, by surface stabilization or by using fences. In Saudi Arabia stabilization of 2.0 m wide strips, laid perpendicular to the direction of dune movement, using oil-based materials, is being widely adopted.
Discussion on ‘A review of geology and engineering geology in Singapore’ by John Pitts
Authors: Morton Keith , Sayer Paul
Published: November 2007

K. Morton and P. Sayer write: Dr Pitts has presented a broad introduction to the engineering geology of Singapore. As he noted, there is considerable room for further investigation and understanding. The geology of Singapore has been well presented previously by the Singapore Public Works Department (1976) and Dr Pitts has summarized this report with comments based on his own observation.

In such a review it might have been better to classify the geology into groups in a manner described, for example, by Andrews
et al
. (1984). This classification can be used to identify those areas where further knowledge on the engineering behaviour would be required from those where the behaviour is reasonably predictable. In particular, the superficial soils would fall into the former category and the moderately weathered to fresh basement would fall into the latter.

Burnett (1984) has suggested that any deposit in the former category which can be repeatedly recognized can be broadly classified on the basis of an assessment of its origin, process of accumulation and final typical land form or shape. Natural geological deposits are divided into two environmental groups: first, sub-aerially formed regolith (essentially terrestrial, non-stratiform) and second, subaqueous stratiform.

It is possible then to identify the properties of the materials on a rational scale rather than discuss the relative merits of localized deposits. A combination of the classification methods (after Andrews
et al
. (1984) and Burnett (1984)) together with the basic engineering properties could be proposed as shown in Table 1. Given this
Mire morphology and the properties and behaviour of some British and foreign peats
Authors: Hobbs N. B.
Published: November 2007

The morphology, succession and flora of British mires is briefly outlined and the influence of these factors on the index and mechanical properties of the associated peat is discussed.

Peat, in view of its exceptionally high water content, is an extraordinary material, yet in many respects it may be regarded as ordinary in as much as the correlations between its various properties and behavioural parameters are little different from those of clay soils except in regard to strength. The cation exchange ability of peat is extremely high and exerts an important influence on its properties. The properties and parameters of some UK bog and fen peats are compared with peats from Canada and other countries.

It is shown that under constrained deformation the so-called secondary compression is the dominant and fundamental process; the consolidation phase is properly regarded as but a temporary aberration. It follows from this that the so-called preconsolidation pressure is a function of the test procedure and thickness of the peat, sample or layer. A fundamental preconsolidation pressure, both time and load induced, does exist but its determination is difficult. Current testing procedures are examined and the errors involved in conventional methods of predicting settlements are explored and evaluated.

The shear strength of peat and the stability of works over mires are not discussed.
Weathering and slope stability on Upper Carboniferous mudrocks in south-west England
Authors: Grainger P. , Harris J.
Published: November 2007

Natural landslides are a common occurrence on inland slopes of Upper Carboniferous strata in south-west England. They range from shallow, translational slides to earthflows, and usually involve soils above and belonging to the zone of completely weathered mudrock. Solifluction was more active in periglacial conditions (due to softening by excess surface water) and formed widespread clayey head deposits found mainly on lower slopes. Translational sliding is more characteristic of temperate environments and locally may be initiated by artesian groundwater pressures on the base of silty clay soils of low permeability where these overlie pervious weathered rock. These slides may develop downslope into earthflows when seepage of groundwater produces softening. The clay soils do not have a high activity or plasticity on the whole, due to the high diagenetic grade of the underlying mudrocks whose non-swelling clay mineralogy they inherit. Measurements of the residual shear strength of the slipped soil at one site shows a curved strength envelope with ϕ′
r
falling to about 15° at high normal effective stress, but with values up to 30° at low stresses. The significance of the variation with normal stress of ϕ′
r
and c′
r
in the analysis of the stability of very shallow landslides makes it important to determine accurately both the laboratory strength and in situ effective stress at low overburden stresses. The direct observation of unstable or susceptible areas before the main ground investigation may be aided by electrical resistivity surveying. Stabilization can usually be achieved by drainage measures, but complete removal of unstable soils is sometimes necessary.
Borehole cements and the downhole environment—a review
Authors: Robins N. S. , Milodowski A. E.
Published: November 2007

A wide range of cements and cement additives are available for borehole construction purposes. The mechanics of cement placement dictate the required properties of the cement slurry, but the borehole environment dictates the cement type. The overall borehole environment is created by the interaction of physical, chemical and biological factors, each of which contribute to cement reactivity and cement durability. Evaluation of borehole cements can be undertaken either using downhole geophysics, or through the investigation of laboratory prepared samples, but neither method usually pays sufficient regard to the borehole environment.
Foundation problems on limestone: A case history from the Carboniferous Limestone at Chepstow, Gwent
Authors: Statham I. , Baker M.
Published: November 2007

Sediment filled bedrock depressions in the Carboniferous Limestone were revealed during construction of a supermarket in Chepstow. They were interpreted as swallets.

An initial site investigation did not reveal the features, which were less than 10 m across and about 8 m deep. They were not suspected at the desk study stage since the site was on a valleyside location and did not lie on an obvious abandoned drainage route.

The features were investigated in less than one week and the investigation and redesign of foundations did not incur any delay to the contract.
An observation on Mohs' Scale of Hardness
Authors: West G.
Published: November 2007

Mohs' scale of hardness, devised by the Austrian generations of geologists. It is a hardness scale for mineralogist F. Mohs in 1824, is familiar to many minerals based on the ability of a harder mineral to scratch a softer one. The scale is as follows:

It has been generally accepted that the scale is one of rank order only and that the steps between the various minerals are not equal. For example, one noted mineralogical textbook (B6rner 1962) says: 'The figures 1 to 10 on the scale merely denote an order of hardness, and have no quantitative significance, and the difference in hardness between successive grades is in fact very variable'. Another (Milner 1962) tells us: 'It is important to realize that Mohs' scale is quite arbitrary and the numbers do not represent any regular mathematical ratio as between one and another'. Indeed, the author himself has repeated this view (West 1981). The purpose of the present note is to present new experimental evidence that shows this belief may have to be reassessed.

During the course of recent research into the wear of tunnelling machine tools, an apparatus was made to determine quantitatively the abrasiveness of rocks. In the apparatus a sharp steel conical point of cone angle 90° is applied to the plane surface of a rock specimen under a total load of 70 N. The rock is then slowly displaced by 10 mm. The abrasiveness of the rock is obtained by measuring the diameter of the resulting wear
Discussion on ‘The influence of ground and groundwater geochemistry on construction in the middle east’ by P. G. Fookes, W. J. French & S. M. M. Rice
Authors: James A. N. , Little A. L.
Published: November 2007

Dr A. N. James and Mr A. L. Little write: Dr Fookes and his co-authors are to be congratulated on a valuable and interesting paper which is similar to work in Saudi Arabia for which the writers of this present discussion were responsible during 1977 and 1978. The present writers were concerned with geotechnical aspects of certain structures being designed for the Royal Commission of Jubail and Yanbu, under whose authority the very large Jubail Industrial Complex was being constructed.

Many of the structures were to be situated on the sabkha areas near Jubail and Al abd Allahand on the Arabian penninsula some 25 km north of the sabkha Al Riyas which has been briefly described by Johnson
et al.
(1973). The present authors had access to extensive investigations of the Jubail sabkha area made by a number of different organizations including: Al-Muhandis Nizar Kurdi, Arabian Engineering Bureau, Sir Alexander Gibb & Partners, Dames and Moore & Basil Geotechnics, Binnie & Partners, Consulting Engineering Office Soilmafco, Pacific Consultants Inc. and Saudi Fugro Ltd. Information available from these investigations was used during the design stages of a variety of large and small structures with different load bearing and settlement requirements.

During the review stages of the project it became apparent that effects of artesian water were an important consideration for all the foundation designs. This aspect of foundation design and construction on sabkha has received very little attention previously although it is mentioned briefly byOwles and Bowman (1981). The artesian pressures
The Working Party Report on Engineering Geophysics
Authors: Hooper J. W.
Published: November 2007

meeting report

This meeting was the first major public airing of the scope of the Working Party Report on Engineering Geophysics, providing the opportunity for all interested parties to participate actively in discussing the organization of the Report. To facilitate discussion at the meeting, all Engineering Group members had been circulated with a detailed breakdown of the main and subsidiary headings of the Report. A selection of engineering geophysics users, rather than practitioners, had also been circulated with selected chapters. It is hoped that the final Report will be published in the
Quarterly Journal of Engineering Geology.

Mr D. N. Holt, the Engineering Group Chairman, opened the meeting with reference to the high standing in which past working party reports are held, and expressed the hope that the standard would be maintained by this report. Mr Holt then introduced Mr P. W. McDowell, the Working Party Chairman.

Mr McDowell outlined the scope of the Report, stating that it was intended not only as a state of the art document, but also as a practical guide for the use of geophysics in site investigation for engineering works. Its main divisions would be:

Specific targets

Engineering applications

Soil and rock properties

Planning of surveys.

Care had been taken not to delve too deeply into contractual matters, but as the state of the art is determined by the way in which geophysical work is contracted out, some comment was necessary. The Report would also serve as a reference source, with a comprehensive bibliography as well
The flood plain deposits of the Lower Thames
Authors: Marsland A.
Published: November 2007

The flood plain of the tidal Thames is underlain with soft clays, peats, silts and sands which in turn rest on gravel. These deposits vary in thickness from a few to tens of metres. As with all soft deposits considerable care is required in order to obtain good quality samples for geotechnical testing. The wide range of soils which often occur down single soil profiles and from location to location can make it very difficult to assign soil parameters for design purposes and careful categorization is required. The presence of varying percentages of organic matter as well as silt and sand lenses in the clays can lead to difficulties in the interpretation of
in situ
tests such as the field vane.

While the foundations for large structures are taken down to the underlying gravel and chalk, problems arise from services and smaller foundations. Stability problems arise during the design and construction of road and flood embankments. Since the gravel aquifer is exposed in the river channel along much of the length, pore water pressures transmitted through gravel during high tides can affect the stability of flood banks. High pore water pressures in the gravel can also lead to instability of excavations unless the pressures are relieved by groundwater lowering. When it is necessary to lower the water pressures for construction purposes consideration needs to be given to the additional settlement of adjacent ground and small structures founded on the alluvium.

The paper looks at the distribution of the various soil types, gives typical geotechnical properties and discusses some engineering implications.
Locating potential borehole sites in a discordant flow regime in the Chalk aquifer at Lulworth using integrated geophysical surveys
Authors: Houston J. F. T. , Eastwood J. C. , Cosgrove T. K. P.
Published: November 2007

Groundwater flow in the Chalk Aquifer at Lulworth is discordant with the surface drainage pattern as a result of flow reversal consequent upon coastal breaching of the aquifer. Siting of boreholes for water supply is thus made difficult, especially since flow is confined to very narrow zones. The use of geophysical techniques has enabled such zones to be identified with varying degrees of certainty. It is important not to place too much reliance on a single technique and to integrate such surveys into an overall appreciation of the evolution of the groundwater flow regime in order to obtain maximum benefits.