bluuebunny/crossref_metadata_2025 huggingface dataset:
P-wave velocity measurements in a machine-bored, chalk tunnel
Authors: Hudson J. A. , Jones E. J. W. , New B. M.
Published: November 2007

During tunnelling trials in the Lower Chalk at Chin-nor, Oxfordshire, two techniques for assessing rock quality based on measurement of P-wave velocity were evaluated. Ultrasonic pulse velocity measurements at 54 kHz were made over 0.2 m path lengths at the tunnel face and the conventional hammer seismograph method was used over 10 m path lengths along the tunnel side wall.

The ultrasonic measurements were obtained by placing transducers on the flat surfaces of circular grooves cut by the tunnel boring machine picks and provided an excellent method for
in-situ
evaluation of local variations in the mechanical characteristics of the chalk. In order to obtain the relation between acoustic velocity and geotechnical properties of the chalk in this region of complex fissuring, it was necessary to compare average values of velocity and chalk properties for successive readings over a distance of 1.6 m which is equivalent to ten times the mean distance between fissures. Linear relations were found for acoustic velocity versus both chalk strength and discontinuity spacing for the range of chalk variability that was encountered.

P-wave velocities from the hammer seismograph observations over 10 m path lengths showed considerably less scatter than the ultrasonic velocities because such a large number of discontinuities was included in each path length but a significant change in values from the range 1.08-1.27 km/s to the range 1.45-1.64 km/s occurred some 35-40 m from the tunnel portal. This increase is directly associated with the change in ground surface level and consequent increase in overburden stress. Moreover, the velocity ceased to increase significantly at an overburden stress of 0.4 MN/m
2
, a level that corresponds well with the stress at which a discontinuity became acoustically closed in laboratory tests. The measurements emphasize the fact that, when the P-wave velocity is used as an indicator of rock quality near the ground surface, it is important to take the effect of overburden stress into account.
Applied petrology—the stability of concrete aggregates
Authors: French W. J.
Published: November 2007

The papers in this issue were presented at an Ordinary General Meeting of the Society in February 1979. They illustrate some of the aggregate problems that can arise in modern concrete and the value of petrological and geochemical techniques in the study of potentially deleterious systems. It is common to regard concrete aggregates as inert filler. Perhaps in Britain this is fair, although in recent years several examples of damage due to aggregate instability have been described. Internationally, the difficulties of finding good aggregate are more profound; British flint may make good concrete but Danish and German flint is often reactive and extremely deleterious. The problems are particularly acute in extreme climatic zones and where hard rock and good gravel is scarce or must be transported for great distances.

The Chairman of the first session, Mr A. D. Robertson of Sir William Halcrow and Partners, referred to the very great interest created by the problem of the behaviour of concrete in the Middle East and recalled that one of the first occasions on which this had been aired was in the Society's meeting room, as recently as 1975. Since the first signs of trouble had manifested themselves in Bahrain the scale of construction in the Middle East had increased dramatically and the earlier problems had been exacerbated by the need to find sources of aggregate in quantities far in excess of earlier demands for use in more elaborate forms of construction capable of sustaining higher stresses. Early considerations of concrete
An introduction to the influence of natural aggregates on the performance and durability of concrete
Authors: Fookes P. G.
Published: November 2007

The production of aggregates for construction is the largest of the extractive industries in Britain. Natural aggregates form the main component, by volume, in the manufacture of concrete but the part played by aggregates in the durability and performance aspects of concrete is still relatively little understood.

The paper summarizes the main physical and chemical considerations of aggregate in concrete, especially those leading to cracking and deterioration. It broadly considers the British specification of aggregates, which has largely been built up from decades of local experience, and emphasizes the need in many locations overseas for more specific requirements on use of aggregates in different climatic and geological settings. The strong influence on aggregate performance by the use of geologically weathered rock is little recognized even in good concrete practice and is highlighted in the paper. In conclusion, suggestions are given for all-purpose aggregate testing programmes.
The influence of serpentinite and other rocks on the stability of concretes in the Middle East
Authors: French W. J. , Crammond N. J.
Published: November 2007

It has been suggested that the expansive serpentinization of olivine can occur in concretes which contain ultrabasic aggregates. This process could lead to the deterioration of concretes and has been blamed for the poor performance of some concretes in the Middle East. This paper reviews the petrology of serpentinite-bearing concretes and mortars made with aggregates collected in the United Arab Emirates. It shows that most, if not all, of the deleterious changes observed in the field can be explained by other mechanisms involving contaminant lithologies and factors not connected with the aggregates; and that olivine has remained unaltered in concretes of up to 40 years in age.
Reactions between aggregates and cement paste—an interpretation of the pessimum
Authors: French W. J.
Published: November 2007

This paper is concerned with the reaction between the alkalies present in the pore fluids of the cementitious phases of concrete and certain siliceous aggregates. The reaction may be expansive and consequently deleterious. Maximum expansion occurs at some definite or ‘pessimum’ concentration of reactive aggregate for any given mortar. The nature of the reaction is discussed and formulae are given which describe the curve of expansion against proportion of reactive aggregate. The magnitude and significance of the coefficients of these expressions are discussed and suggestions are made for the limits to be set on the allowable expansion and other design parameters if the effects of the reaction are to be minimized.
Recharge mechanisms and groundwater flow in the Chalk and drift deposits of southern East Anglia
Authors: Lloyd J. W. , Harker D. , Baxendale R. A.
Published: November 2007

The hydrochemistry of groundwaters in the Chalk and glacial drift deposits are detailed to show the distribution of different hydrochemical types in relation to recharge. Corrected radiocarbon ages of 25 groundwater samples indicate that old groundwaters ranging in age up to 30 000 years exist beneath the boulder clay in the interfluve areas. Recharge and flow into the Chalk aquifer are shown to occur predominantly in the valley areas and to be controlled by the distribution of drift deposits. The role of sands and gravels below the boulder clay in promoting horizontal groundwater flow is demonstrated.
Relic landslip in west Northamptonshire
Authors: Biczysko S. J.
Published: November 2007

This paper presents case histories of two encounters with relic landslip features in Jurassic strata. The geometry and possible mechanism of growth of the landslips are considered, together with the effects of the reactivation of the landslips on the construction of Daventry By-Pass. The remedial options to stabilize the landslips are discussed together with the selected solution of ‘on-going’ maintenance. The uncertainty of detection of relic slip surfaces on hillslopes displaying little clear geomorphological evidence of previous movement is highlighted.
Engineering geology for a major industrial complex at Aughinish Island, Co. Limerick, Ireland
Authors: Clark R. G. , Gutmanis J. C. , Furley A. E. , Jordan P. G.
Published: November 2007

Geological investigation of an area of Carboniferous Limestone before and during site grading has revealed a mound and basin structure thought to be the product of mud bank rather than reef growth. A number of large linear features, associated with secondary dolomitic limestone, has been found together with infilled cavities of considerable depth. These represent an ancient karstic environment modified by glacial processes. The paper describes the investigations carried out to locate these features together with the strength parameters and design criteria used for the materials.
Fine-grained sediments: Terminology
Authors: Stow Dorrik A. V.
Published: November 2007

Fine-grained sediments are those rocks, both hard and soft, carbonate and clastic, that have a dominant grain-size in the clay or silt grades (<63 μm). They are the most abundant sediments on the earth's surface and form between 50 and 750f the geological column. Classifications of fine-grained sediments have been based most commonly on texture and fissility, and secondarily on mineralogy, chemical composition, colour, degree of metamorphism and depositional environment (
Picard 1971
). Different terminologies have, therefore, arisen but the state of confusion is less severe than that in, for example, the coarser-grained sediments that have been relatively more throughly studied and subdivided.

It is clearly important for improved communication within the earth sciences (for example, between sedimentologists and engineers) that a generally-accepted standard terminology is widely used. It is still appropriate for fine-grained sediments that the term should be simple and readily applied in the field. The results of more detailed laboratory or field analyses can then provide suitable descriptive modifiers to the basic terms. This is the aim of the terminology out-lined in Table 1.

The term mudrock implies a siliciclastic composition. Other fine-grained sediments can be designated carbonate mudrocks, silica mudrocks, and so on. A similar terminology is then appropriate (e.g. carbonate siltstone, silica mudstone) but a range of other terms, such as chalk, chert, diatomite and ooze, are also widely used. Classification of these sediments is not discussed here.
The terminology presented in Table 1 is broadly in line with that proposed by many previous
The distribution of Lower Palaeozoic mudrocks in Britain
Authors: McKerrow W. S.
Published: November 2007

Mudrocks occur as thin graptolitic shales, as shelf deposits, and within thick turbidite sequences. It is the thick turbidites sequences that provide the most extensive areas of outcrop, especially in the Grampian Highlands, the Lake District and the Welsh Basin. Thin shale bands in the Southern Uplands can provide engineering hazards. Shelf muds are common in the Tremadoc and Silurian shelf sequences of England. Reconstructions of the contemporary palaeogeography suggest possible source areas in Scotland, the Irish Sea landmass and the East Midlands of England for some of the Lower Palaeozoic sedimentary sequences, but others are of unknown provenance.
Field investigation of British Mesozoic and Tertiary mudstones
Authors: Gallois R. W. , Horton A.
Published: November 2007

Thick mudstone formations crop out over large areas of Britain and it is commonly necessary to subdivide them and make correlations within them for civil engineering and other economic purposes. Although at first sight many of these formations appear to consist of monotonously uniform lithologies that are commonly deeply weathered and rarely exposed, they can yield sufficient field data for detailed stratigraphical and structural interpretations to be made. Such data includes lithological variations and macrofunal changes used in combination with field mapping and geophysical borehole logging. In almost all cases the geological subdivisions so recognized are more detailed than the variations revealed by indiscriminate engineering soil-testing. Visual inspection of mudstones in the field, combined with selective testing, can provide a better guide to their behavioural characteristics.
A review of the hydrogeology of British onshore non-carbonate mudrocks
Authors: Tellam J. H. , Lloyd J. W.
Published: November 2007

Mudrock hydrogeology is important from the point of view of waste disposal, subsidence and aquifer analysis, and yet in Britain there has been little systematic study of the subject. Here a preliminary assessment is made of the concepts involved and the data already available. A wide variety of techniques can be used for measuring hydraulic properties of mudrocks, and often both laboratory and field determinations are necessary in order to gain an appreciation of the relative importance of the various possible flow mechanisms. It is uncertain to what extent the conclusions obtained by investigating ideal media are applicable to natural systems. However, research into natural systems elsewhere in the world indicates the potential importance to groundwater flow of lithification processes. The mudrocks of Britain can be divided into two groups, a pre-Mesozoic group, where fissure flow predominates, and a post-Palaeozoic group, where inter-particle flow may be present and where high rock compressibility may be important. As expected, both groups have extremely low hydraulic conductivities; the latter group is also characterized by moderate to high total porosities and by very high specific storage coefficients. Typical properties are presented.
Hydrogeology of the Syrian steppe and adjoining arid areas
Authors: Khouri J.
Published: November 2007

Several major sedimentary basins, in which thick sequences of Palaeogene marls and Neogene-Quaternary sediments have accumulated, can be distinguished in the arid zones which extend from the Great Nefud in Saudi Arabia to the Euphrates river in Syria. Structurally, they represent areas of relative subsidence formed between the Rutbah-Ha'il arch, the Jordan uplift and the Halab uplift.

The Syrian steppe and adjoining areas can be subdivided into eastern, western and north-western regional ground-water flow features which follow north-westerly (Palmyrian) and south-south-westerly trends.

The eastern regional flow system in the permeable Palaeozoic and Mesozoic strata is related to the development of the broad domal structure of the Rutbah-Ha'il arch. Transmission of flow parallel to a system of north-north-westerly lineaments occurs from the Rutbah area of Iraq to the Wadi-el-Miah area of Syria. Step faulting and the minor anticlinal structures developed in this latter area seem to influence upward leakage from the deeper aquifers into the Cretaceous and Palaeogene chert aquifers. Groundwater transmitted westwards from the Rutbah-Ha'il arch is retarded by the marly facies of the Upper Cretaceous and Palaeogene in the Wadi Sirhan basin. Minor chert aquifers, however, transmit a portion of the flow. Discharge occurs in a zone along the eastern margin of the Wadi Sirhan.

The western regional flow system differs from that in the east in that hydraulic interconnection between the upper aquifers with the underlying Mesozoic is negligible. The recharge zone for this system coincides with the higher portion of Jebel-el-Arab. Groundwater transmission in the complex sequence of basaltic sheets of the Syria-Jordan plateau region is controlled by two fracture systems, in addition to the usual lava flow conduits.

The north-western regional system is recharged in the Anti-Lebanon and flows south-westwards in fractured limestones and dolomites. Discharge occurs mainly via karstic springs. Upward leakage may occur into the Ghouta gravel aquifer and eventually may be lost by evaporation from Ateibe lake. In the S Palmyrian moutains zone, a flow pattern controlled by linear
en-echelon
structures transmits groundwater in a north-easterly direction. Discharge from the system takes place at Sabkhet-el-Mouh, south of Palmyra. Hydrogen sulphide water, issuing along the south Palmyrian regional fault system, suggests relatively deep groundwater circulation. Isotopic studies indicate that groundwater age increases along the Palmyrian flow system.
Fitting failure envelopes by the method of least squares
Authors: Bland J. A.
Published: November 2007

A proposed form of Mohr's failure criterion is shown to reduce, under certain conditions, to several classical failure criteria. The failure envelope for each criterion is then determined using the method of least squares.
The identification of critical factors affecting rock durability in marine environments
Authors: Dibb T. E. , Hughes D. W. , Poole A. B.
Published: November 2007

Degradation of rock under marine conditions can be ascribed to three general mechanisms; spalling, abrasion and large scale, catastrophic fracture. The physical disaggregation of a rock fabric can be assessed in terms of the forces of ‘attack’, such as salt crystallization pressure and rock impact forces, acting against the coherence of the rock fabric.

This coherence (and hence durability) is examined in terms of fracture toughness (K
1C
) and the Griffith fracture criteria for brittle solids which relate the maximum length of discontinuities present in a rock to its tensile strength. The relationship of tensile to compressive strength is reviewed and their relative merits are discussed. The use of standard engineering tests in the assessment of potential rock durability is also examined.
Discussion on ‘Hydrogeology of the Umm Er Radhuma aquifer, Saudi Arabia, with reference to fossil gradients’ by W. Bakiewicz, D. Milne & M. Noori
Authors: Doornkamp J. C.
Published: November 2007

Dr J. C. D
oornkamp
writes: The synthesis provided by Bakeiwicz
et al
. has to be admired for its scope and enormous regional extent.

The difficulty with such analyses is that sometimes the details do not fit. This is the case for Bahrain, as shown in their figs 3 and 4. The interpretation given to the interior basin of Bahrain as a portion of a ‘solution collapse feature’ cannot be supported by evidence on the ground. This interior basin is not just one but 10 discrete draining basins partly eroded by water and partly excavated by wind. The net effect is to produce an eroded anticline.

In their fig. 4 Bakiewicz
et al
. identify palaeo-river courses on the southern portion of Bahrain: these do not exist. What appears to have happened is that the long dark trails of flints associated with outcops of the West Rifa Flint Formation (part of the Damman Formation of Bakiewicz
et al
.), as concentrated by synclinal folds, have been mistaken for river gravels. This misinterpretation could happen, of course, if only air photo interpretation was available to the authors.

Both of these points can be followed up more fully by reference to

Doornkamp
et al
. (1980)

.

The authors wish to thank Dr Doornkamp for his useful comments.

Without going into details of Bahrain geomorphology, which is outside the scope of the paper, there is no doubt that a solution collapse feature, associated with the evaporites of the Rus Formation, does exist on Bahrain. This
In situ seismic and electrical measurements of fracture anisotropy in the Lincolnshire Chalk
Authors: Nunn K. R. , Barker R. D. , Bamford D.
Published: November 2007

Using recently developed modifications of the conventional seismic refraction and electrical resistivity techniques,
in situ
measurements of P-wave velocity and resistivity anisotropy have been made at four sites in North Lincolnshire where the Chalk is overlain by a thin covering of drift. All sites showed significant velocity and resistivity anisotropy with the direction of the maximum observed velocity and resistivity being consistent with direct fracture observations made at two quarries within the area. It is suggested that such surface geophysical measurements can be very useful in predicting the predominant fracture direction in near-surface bedrock in which fractures are near vertical.
The improvement of colliery spoil
Authors: Kettle R. J.
Published: November 2007

Unburnt colliery spoil, or minestone, is the waste product from coal mining and this study has been directed towards examining its use in highway construction. An initial review is presented which deals with its bulk utilization in embankment construction and incorporation in the pavement structure. In view of its inherent low quality, some form of stabilization is necessary to produce a material capable of carrying the stresses associated with pavement structures. The work reported in this paper has been concerned with the use of cement.

The results reported have been obtained both from extensive laboratory studies and from associated field trials. The suitability of the stabilized spoils has been assessed using laboratory characteristics such as strength, frost resistance and resistance to immersion. It is clearly shown that certain colliery spoils can be stabilized with cement to produce material suitable for inclusion in pavements both as sub-base or road-base material. Field data is also included which indicate the compaction levels and strength that can be achieved on site. The results again demonstrate that cement-stabilized colliery spoil can be considered for incorporation in the pavement layers.
Notes on water movement in the unsaturated zone
Authors: Clark L.
Published: November 2007

Recent assessment of the resource potential of the Yazor Gravel Aquifer near Hereford (
Liddament & Clark 1980
) has provided evidence which supports the concept of physical controls proposed by
Wellings & Bell (1980, 1982)

and suggests that the same controls govern the movement of water through unsaturated granular material as well as Chalk.

The Yazor Brook drains an area of about 50 km
2
west of Hereford and north of the River Wye. The lower and central parts of the Yazor Valley are infilled by superficial glacial and post-glacial sediments up to about 15 m in thickness. A significant proportion of these sediments are ill-sorted glacial-outwash sands and gravels which make up the local, but important, Yazor Gravel Aquifer System. A mathematical model of the Yazor Gravel Aquifer was constructed but there were great problems in modelling the water balance of the system. The major problem was in quantifying the recharge to the aquifer, because the traditional Meteorological Office approach, using the soil moisture deficit (SMD) concept, did not appear to work.

The behaviour of the water table in two observation wells equipped with continuous water level recorders help to show quite clearly that, in the Yazor Valley, the traditional SMD concept cannot be applied entirely. Recharge can take place where an SMD exists and considerable evapotranspirative losses can occur by upward flux from quite deep water tables.

Recharge

Through each summer all, or almost all, rain should be soaked up, removing the SMD. In
Towards the prediction of subsidence risk upon the Chalk outcrop
Authors: Edmonds C. N.
Published: November 2007

Surface karst landforms such as solution pipes, swallow holes and dolines are well developed on the Cretaceous chalk outcrop in Britain. The local frequency of these solution features on the chalk can be as high as on any of the best developed karst areas on other British limestones. However, the overall frequency of solution features for major regions of the chalk outcrop is much lower.

Solution pipes, swallow holes and dolines often represent an engineering hazard because of metastable conditions, which, if disturbed, can result in ground subsidence. The research described here is aimed at producing a model to predict areas of subsidence risk upon the chalk outcrop. Considerations for the prediction of subsidence risk are outlined with preliminary analysis for two areas.
Comparison of different methods of estimating infiltration at a landfill site in south Essex with implications for leachate management and control
Authors: Holmes R.
Published: November 2007

As a result primarily of rainfall infiltration through waste materials, all landfill sites in the United Kingdom will produce leachate. A procedure for estimating rainfall infiltration through landfill sites founded on readily and cheaply available Meteorological Office data is presented. This accounts for the distribution of rainfall throughout the year and shows that for a site in south Essex, between 14 and 34% (average 24%) of annual rainfall infiltrated in the past eight years. Winter and summer operational stategies which may minimize the production of leachate are summarized. These are based on minimizing rainfall infiltration in winter months and taking up the shortfall between potential evapotranspiration and actual evapotranspiration in summer months.
A review of geology and engineering geology in Singapore
Authors: Pitts John
Published: November 2007

A mass rapid transit (MRT) railway system is soon to be constructed in Singapore. Attention is being paid to details of the engineering geology of the island, which are generally not well documented or understood. The main solid formations, both igneous and sedimentary, are deeply weathered, often with an abrupt boundary between completely weathered and slightly to moderately weathered rocks. They have a high degree of fracturing and the sedimentary Jurong Formation has a high but variable dip. They are overlain by Quaternary deposits, many of which have poor geotechnical properties. A soft marine clay and overlying peaty deposits present particular problems in excavations. Each has a low strength and high compressibility and water tables are close to the ground surface. Variations in the geotechnical characteristics of the marine clay are now being recognized. The soft deposits are mainly found in buried channels cut during lower stands of sea level in the recent geological past. The channels have steep sides, and at many sites geotechnical conditions change very rapidly.
The characteristics and rates of the various slope degradation processes in the Barton Clay Cliffs of Hampshire
Authors: Barton M. E. , Coles B. J.
Published: November 2007

Research is in progress to determine the nature and pattern of the degradation processes in an actively eroding stretch of the Barton Clay cliffs in the Naish Farm area of Highcliffe, Hampshire. In response to loss of beach material the rate of recession has accelerated and is currently averaging 1.9 m/year, resulting in steepening of the overall cliff angle from an average of 13° in 1947 to a maximum recorded average of 19° in 1976. The presence of three preferred bedding plane shear surfaces at various elevations within the cliff produce a benched type of cliff profile, comparable with that seen in the Gault and Lias Clay controlled cliffs of Fairy Dell, Dorset but in contrast with the published descriptions of London Clay cliffs.

The degradation processes include scarp slumping, spalling (including toppling and soil falls), bench sliding (involving movement of colluvium over a preferred bedding plane), debris sliding (including movement of screes over clay scarps), mud sliding (i.e., the traditional lobate ‘mudflows’), mud runs (true flows), stream (or gully) erosion and man-related processes. Regular surveying and monitoring using a variety of techniques and having to surmount difficult field conditions, has begun to elucidate the characteristics, rates and inter-relationships of these processes. A flow chart representing the systematic transfer of soil from the
in situ
state via various colluvial modes (including the three bench levels)
en route
to the sea and an accompanying colluvial soil budget for the year July 1981 to July 1982 has been drawn up. It is shown that bench sliding is by far the most significant process in terms of volume of colluvium moved through the under-cliff, accounting for 930f the total volume of colluvium contained in the area. Mud and debris sliding, although important processes, are of relatively minor significance.
Discussion on ‘Delineation of saline intrusion in the Dungeness Shingle Aquifer’ by Okomeno Ulaya-Egbe Oteri
Authors: Fox R. A.
Published: November 2007

Mr R. A. Fox writes: Mr Oteri's paper presents a limited review of the aquifer at Dungeness. However, the problem of saline intrustion is a complicated one and we would like to comment on several aspects where the content of the paper may be misleading.

On page 48, the author notes that the lowest resistivity layer was interpreted as representing a saline water-saturated fine sand interface, which was accepted as the fresh water-saline water interface. He then goes on to note on page 49 that ’the depth of the fresh water-saline water interface beneath sea level in Dungeness is considerably smaller than that expected from the Ghyben-Herzberg principle‘. This states that, due to water density differences, the interface is about forty times deeper below mean sea level than the fresh water height is above sea level. A diagram to illustrate this point and the variations in interface level which apparently occur would be an interesting addition to the paper.

The conclusion on page 50 infers that gravel-winning from the aquifer, already thinner than expected, raises the level of the saline water and encourages the intrusion of the saline wedge in the coastal fringe. However, comparing Figs 1 and 7 it is evident that the areas of thinner fresh water lens are more directly associated with supply well locations than gravel-winning areas. This tends to be confirmed whenFig. 7 contours are superimposed on Fig. 2.

Ready Mixed Concrete (UK) Limited is one of the companies referred to in the introduction of
Mr A. M. P
odhalicz
writes
Authors: Phodalicz A. M.
Published: November 2007

Engineering geologists and geotechnical engineers will welcome Graham West's review of the current practices in the site investigations for tunnels, and their effectiveness.

West points out some discrepancies between the computer-predicted model of the geology along the route of the Jubilee Line extension and the results of the site investigation boreholes.

Those discrepancies were a necessary consequence of simplifications needed to design a computer model used by Sir William Halcrow & Partners and Mott, Hay & Anderson (1973). The model was based mainly on logs of water boreholes from the London area which generally contained simple descriptions of lithology without giving stratigraphic provenance of the formation. Therefore, a deliberate decision has been made to treat the Blackheath Beds and Woolwich and Reading Beds as a single lithological unit.

My recent Australasian experience prompts me to comment on two other points made by West. Where, on mountainous sites like Dinorvic, access to borehole positions is difficult, helicopters can be used to advantage; the whole operation of dismantling the rig into air-portable parts, moving it and reassembling it ready
to drill on a new site can be carried out in a single day.

In difficult strata, such as very weak friable Pliocene sandstone or volcanic rock with clay-filled joints, full core recovery can often be achieved using large diameter (PQ3) triple tube wireline core barrels. Cores of firm to stiff clays obtained in this way are considered (when sealed on site) to be more suited for triaxial testing than samples from normal
Impact of engineering structures on tidal flow and sediment distribution in the Thames
Authors: Kendrick Mary P.
Published: November 2007

The Thames is one of the most suitable estuaries in which to examine how engineering works affect flow and sediment movement. Case histories are given to demonstrate the important influence of both structure location and structure design on river conditions. They also illustrate methods available for predicting the consequences of works or for identifying cause and effect following changes in estuary regime. Finally, they provide warning of the penalties of failure to take account of the hydraulic implications of a new structure.
Deep Foundations in the River Hull
Authors: McMillan P. H.
Published: November 2007

The River Hull Tidal Surge Barrier is located at the confluence of the rivers Hull and Humber to exclude surge tides from the river Hull and any consequent flooding from the city of Hull. This paper discusses changes to the design concept for the foundations of the Barrier necessitated by the geotechnical investigation data. Other features of the Barrier project have been described elsewhere (

Fleming
et al
1980

).
Chemical soundness test on Carboniferous Limestone samples from the Bristol area
Authors: Al-Jassar S. A. , Hawkins A. B.
Published: November 2007

Soundness tests using sodium sulphate and magnesium sulphate solutions on seven lithologies from the Carboniferous Limestone of the Bristol area are reported. The loss percentage from the two solutions is notably different. The factors which affect this variation are considered. The results stress the differing behaviour of the main limestone groups and indicate the danger of using the single word ‘limestone’ and assuming it has a single set of properties.
Discussion on ‘A55 Pwll Melyn slip and remedial works: a case history’ by A. Siva Subramaniam and R. W. Carr
Authors: Child G. H. , Norbury D. R.
Published: November 2007

G. H. C
hild
and D. R. N
orbury
write: From our investigation of the slip when active we would like to make the following comments. Although we did not find shear zones in borehole samples, overnight movement of drill casing in two holes and positive response from a slip indicator in another enabled us to identify the surface of sliding under the embankment side slope which the authors confirmed. We disagree with the authors on the location of the back of the slip, considering the crack in the road to be a secondary feature. In our investigation we considered the primary slip surface to be as shown on Fig. 1 Figures 2 and 3 show the top and toe of the slip on 25 October 1976. The casing of the borehole commenced on the verge and referred to in the paper can be seen in Fig. 2 At this stage major movement had occurred and was all downslope of the road. Figures 3 shows the surface ruckling that had already occurred in the field below.

Because of the large crack in the embankment side slope we question the authors’ conclusion regarding the significance of pore water pressures in the fluvioglacial deposits uphill from this crack. Pore water pressures to their line A or above seem most improbable since this would imply flooding of the old A55 road.

We agree that the embankment fill was relatively permeable; gradings indicated that it was probably more permeable than the fluvioglacial sand. Therefore, a feature
The weathered zone aquifers of the basement complex areas of Africa
Authors: Jones M. J.
Published: November 2007

A major groundwater resource across the high African Plateau is shown to occur within the thick overburden derived by
in situ
chemical weathering of the underlying crystalline Basement Complex. The saprolite aquifer horizon is identified at the base of this weathered zone. The chemical weathering processes that produced this aquifer horizon are largely controlled by circulating groundwater, and this in turn is a function of the climate. The saprolite profiles tend to have similar characteristics over a wide variety of rock types. The geomorphological development of the plateau by cyclic erosion has resulted in a predictable distribution of the aquifer and the analysis of data from over one thousand wells shows it to be hydrogeologically very uniform.
The stabilization of some arid zone soils with cement and lime
Authors: Akpokodje E. G.
Published: November 2007

Tests on three groups of Australian arid zone soils indicate that cement is a more effective stabilizing agent than lime. Sandy soils rich in gypsum and bassanite do not respond to stabilization. The cement stabilized clayey soils must be adequately protected against increase in moisture content.
Large-scale toppling within a sackung type deformation at Ben Attow, Scotland
Authors: Holmes G. , Jarvis J. J.
Published: November 2007

The southwest slope of Ben Attow (NH 010180) features numerous obsequent (uphill-facing) scarplets which are up to 10 m high and 800 m long (Figs 1 and 2). de Freitas and Watters (1973) discussed similar features at Glen Pean, Scotland, invoking obsequent-scarplet formation by toppling. The Ben Attow slope exhibits the largest extent of obsequent-scarplets in Scotland known to the authors. This note examines its mode of instability and the formation of obsequent-scarps.

The slope is composed of coarse Moinian psammites of locally varying metamorphic grade. Joint surveys revealed the presence of four joint sets (Fig. 3): one parallel to the foliation (F), one striking parallel to and dipping into the slope (J1) and two sets that dip gently west (J2 and J3). The scarplets strike subparallel to J1 and terminate westwards at a 1 to 2 m high step-like feature.

Watters (1972) undertook a reconnaisance investigation of the slope and hypothesized that the scarplets were formed by sequential upslope separation and translation of blocks on a failure plane at depth. This was followed by erosion upslope of the tension cracks between displaced blocks and their later infilling with slope debris. However, no slide toe exists at the base of the slope, nor is it likely that there ever was one, since any erosion of a toe would have removed the essentially delicate obsequent-scarplets as well. Further,
in situ
rock crops out across the base of the slope. The scarplets are less than 30 m apart in places and translation
Infra-red linescan survey at Altnabreac, Northern Scotland
Authors: Black J. H.
Published: November 2007

During 1978, a desolate stretch of moorland, bog and lochans, around Altnabreac in northern Scotland, became famous. Apart from being the place where British Rail ‘lost’ a train, it was here that the first (and to date the only) UK field investigation into the suitability of granite as a host for high level radioactive waste was carried out. The objective of the work was to assess how easy it would be to measure the parameters necessary to predict the outcome of waste disposal at such a site. Despite the premature termination of the programme in 1981, much interesting work in an unusual hydrogeological environment was completed. Since hydrogeology has a major impact on safety assessment, understanding the movement of groundwater in fractured crystalline rocks, such as those underlying Altnabreac, was essential. In particular, the role of faults and major joints in controlling the directions of flow and the recharge and discharge zones was uncertain.

The hydrogeological investigations included measurements in the twenty seven boreholes which were drilled, some limited surface hydrology and some preliminary groundwater flow modelling. The bulk of the data was from the boreholes which gave no direct information on the areal distribution of groundwater flow. Whilst the modelling indicated recharge and discharge areas, the groundwater component of stream flow was likely to be small and therefore the shore of the lake. Less spectacular, but perhaps more interesting from a groundwater viewpoint, are the warm springs within the swarm of dubh-lochs south of the loch. In this area
Energy potential of Irish groundwaters
Authors: Aldwell Christopher R. , Burdon David J.
Published: November 2007

The energy potential of Irish groundwater is assessed, and its sources summarized. The two sources of energy, solar and geothermal, are outlined. The manner in which water and energy are united is described. The recovery of energy may be from the warm springs areas, from the tepid springs areas or from the high yielding cold aquifers underlying some 27% of the country. Heat pumps will be essential for their development. It is concluded that both solar and geothermal energies are of importance in Ireland; that energy extraction from the warm and tepid springs has limited potential; and that cold groundwater offers the best energy potential from Irish groundwaters.
Thermal energy storage studies in the Lower Greensand aquifer in Cambridgeshire
Authors: Kitching R. , Adams B.
Published: November 2007

A field experiment has been carried out in the Lower Greensand near Cambridge to test the feasibility of injecting, storing and recovering heat in this formation. Approximately 1500 m
3
of water at about 60°C were injected into the Lower Greensand over a period of 78 days. After storage for 105 days, the heat was abstracted over a period of 97 days. Over this single cycle of operation 33% of the injected energy was recovered. This proportion is likely to increase significantly with further injection/abstraction cycles. Increasing the amount of heat injected was also thought likely to reduce losses and increase the proportion of heat recovered.

A digital model of the Aquifer Thermal Energy Storage (ATES) system was set up and calibrated on the Cray IS system at the University of London Computer Centre. It was then used to predict the behaviour of larger ATES systems both on inter-seasonal and diurnal bases. Energy recovery factors of over 66% appear to be feasible.
Fluctuating, non-homogeneous changes of hydraulic conductivity in porous media
Authors: Goldenberg L. C. , Mandel S. , Magaritz M.
Published: November 2007

Evidence of formation of entrapped saline bodies of water in a porous medium where fresh water displaces flowing sea water was observed in laboratory experiments, carried out on aquifer sands containing clay minerals. When sea water was flushed from these sands by fresh water, fluctuating changes of EC (electrical conductivity) appeared in the sample, and the hydraulic conductivity of the entire sample fluctuated before a lower value of hydraulic conductivity stabilized.

These results are explained by a sequence of mechanisms: (a) formation of small pockets of seawater surrounded bysemi-permeable membranes of deflocculated clay minerals; (b) bursting of the pockets by osmotic pressure and release of trapped sea water; and (c) deflocculation of clay minerals in the pockets formerly occupied by sea water.
The restoration of buildings constructed with Menorcan limestone
Authors: Laurie J. B. , Robertson R. H. S. , Vicente M. A.
Published: November 2007

Accelerating weathering of the stonework of an 18th century building in Mahó n, Menorca, has given cause for concern. The nature and causes of the deterioration of the limestone were studied by X-ray diffraction, partial chemical analysis, differential thermal analysis and scanning electron microscopy. In the light of the results the following recommendations could be made with some confidence: replacement of most affected blocks by the more resistant dolomite; replacement of less deteriorated limestone by a tinted mortar; and the provision of a sacrificial coating of a lime wash.
Sand, gravel and crushed rock aggregates for construction purposes
Authors: Sims Ian
Published: November 2007

1. Introduction

Engineering geology has traditionally been concerned more with interaction between the engineering structure and its geological environment than with the performance of rock aggregates in the structure itself. In recognition of this imbalance, the Engineering Group of the Geological Society established a Working Party in 1978 to compile a reasonably comprehensive document covering the most important aspects of natural and crushed rock aggregates used for construction purposes. The objectives of the Working Party are set out in detail in Section 1 of the Working Party Report, which is being published by the Geological Society in separate book form.

The membership of the Working Party, under the Chairmanship of Professor Peter Fookes, reflected a broad range of expertise and consisted of experienced individuals involved with construction materials, including producers, specifiers, users and researchers. The Working Party members are listed at the end of this summary.

The first complete draft of the Report was submitted for open discussion at a one-day session of the 17th Annual Regional Meeting of the Engineering Group in 1981 at Bangor. A great number of suggestions arising from the open discussion have been considered in the preparation of the final Working Party Report; additional advice has been obtained from a considerable body of corresponding members and professional organizations. The Working Party Report contains a full list of acknowledgments.

The Report was written for a wide audience and is intended to provide basic information on subjects that are new to the reader as well as serving
Discussion on ‘Large-scale toppling within a sackung type deformation at Ben Attow, Scotland’ by G. Holmes & J. J. Jarvis
Authors: Whiteside P.
Published: November 2007

P. W
hiteside
writes: Holmes & Jarvis have inferred that the obsequent scarplets on Ben Attow have formed as a result of movement of the jointed rock mass, yet they present no evidence that movement has occurred. In fact they go so far as to say that there are no signs of recent movement on the slope.

It would undoubtedly be difficult to find such evidence since these Moine Psammites are likely to present a fairly monotonous sequence in which displaced lithologies would not be apparent.

However, one may reasonably expect the scarplets to show some slickensiding, the orientation and sense of which could perhaps preclude its having been formed during some other, earlier joint movement.

In the absence of any actual evidence of movement it is necessary to discuss alternative explanations and in particular to give reasons for assuming that the scarplets have not just simply formed by erosion. Such erosion could, for instance, have occurred during glaciation by plucking of rock blocks by ice.

If the evidence for toppling movement is simply based on the present morphology of the hillside then I would suggest that the erosion explanation is perhaps more likely.
Discussion on ‘An observation on Mohs' scale of hardness’ by G. West
Authors: Gerrard A. J.
Published: November 2007

A. J. Gerrard writes: In his paper, the author provides valuable new information on the hardness of minerals and establishes, quite convincingly, that the grades on Mohs' scale of hardness are spaced in a generally systematic manner. This is useful evidence, largely substantiating the work carried out in the Department of Mining Geology at the Royal School of Mines, London in the 1960s and reported by Duncan (1969); however, this work seems to have been overlooked. The ten minerals on Mohs' scale were investigated using both Vickers and Knoop diamond indenters. A virtually linear relationship was obtained when the logarithm of Mohs' hardness number was plotted against the Vickers' microhardness value. This allowed a recomputation of Mohs' numbers which established that the numbers are far from arbitrary and are spaced in a reasonably systematic manner, except possibly for the value for diamond. In comparing these results with those presented by West, the only difference is that the Vickers' microhardness value places orthoclase feldspar closer to apatite and further away from quartz. Apart from this discrepancy the results are very similar. It is not possible to compare the results further because no detailed information is provided concerning the way in which the experiments were conducted. It is well known that mineral anisotropy affects hardness, different values being obtained on different crystal faces as well as quite considerable variation on individual faces. Hardness variations are also affected by the relations between cleavage plane orientations and the direction of indentation. Presumably this accounts