bluuebunny/crossref_metadata_2025 huggingface dataset:
A map of Belfast for the engineering geologist
Authors: Bazley R. A. B.
Published: November 2007

T
he geological map
should be consulted at an early stage in any project analysis, but in view of the limitations of the standard map we in the Geological Survey of Northern Ireland have felt the need to orientate the product more towards the requirements of the engineer. The first result, the Belfast Three-Inch-to-One-Mile (1:21120) Map—Engineering Edition—is scheduled for publication in 1970. The choice of scale was limited to that of the only suitable topographic base-map available, but as the base is reduced from the six-inch map the topographic detail allows sites to be precisely located. The topographic map is overprinted with a conventional coloured geological drift map, and the front of the sheet also bears a horizontal section. On the reverse side is a table of rock and soil characteristics, a brief account of the geology, a rock-head contour map of the city area and a selection of borehole records.

Although a geological map is, of necessity, always an interpretation and not strictly a record of fact, Belfast is a suitable area to attempt a new approach. Here a wealth of borehole and excavation evidence, and recent geological remapping of most of the area, make possible a higher degree of accuracy than is normally possible.

The main foundation engineering problem in the city of Belfast is the widespread occurrence of soft post-glacial Estuarine Clays which have a very low bearing strength. Isopachytes for these deposits are superimposed on the geological map, and show that thicknesses of over 15 m occur
Ground-water management in England and Wales
Authors: Downing R. A.
Published: November 2007

1. Introduction

T
he average rainfall
over the 58 000 sq miles (150 000 km
2
) of England and Wales is 35-6 in (889 mm). About half is evaporated or transpired by vegetation and the remainder, representing some 41000m.g.d. (186 × 10
6
m
3
/d) infiltrates the ground or becomes surface run-off. Under the terms of the Water Resources Act, 1963, the River Authorities have granted licences allowing an average abstraction of 24 000 million gallons of water each day (109 × 10
6
m
3
/d). The principal demands for this water are indicated in Table 1.

The total includes 15 000 m.g.d. (68 × 10
6
m
3
/d) required for cooling purposes, mainly by the Central Electricity Generating Board. This does not represent a measure of consumptive use; this total also includes some brackish water. If water for cooling is excluded, licences for ground water represent about 25 per cent of the total.

In south-east England (as defined in Anon 1966) the total licensed abstraction of 5500 m.g.d. (25 × 10
6
m
3
/d) includes 3200 m.g.d. (14−5 × 10
6
m
3
/d) used for cooling purposes of which 2600 m.g.d. (11−8 × 10
6
m
3
/d) is brackish water from tidal stretches of rivers. Some 2900 m.g.d. (13−2 × 10
6
m
3
/d) of the total is from inland waters representing about 44 per cent of the residual rainfall. If saline water for cooling purposes is excluded the quantities licensed from surface and ground water sources are 1500 and 1400 m.g.d. (6−8 × 10
6
and 6−4 × 10
6
m
3
/d) respectively. The figures quoted above represent gross use; net use which takes into
Assessment of reservoir feasibility
Authors: Knill John Lawrence
Published: November 2007

The value of geological information to an engineering project is at its greatest during the design phase and this situation is most clearly illustrated by the methods adopted in the location and design of reservoirs. The principles which determine watertightness are outlined and illustrated with regard to specific case histories. Attention is drawn to the differences between mass seepage through a reservoir flank and leakage through a defect in the rock structure over a more limited area. The methods which can be used to prevent or control groundwater flow are reviewed in relation to dam design and foundation geology. Apart from the question of watertightness, which arises in all cases of reservoir construction, the additional factors which determine reservoir feasibility, such as reservoir loading and seismic activity, and valley-side stability are examined. The geological information obtained early in project development and often at very limited cost may, therefore, be critical to fundamental engineering decisions which can influence the whole viability of the scheme.
Some aspects of reservoirs in chalk and acid volcanic rocks
Authors: Newbery J.
Published: November 2007

This discussion deals with some aspects of geological defects arising in soluble rocks and volcanic terrain. As either of these settings would require an entire session to cover them at all adequately the remarks are limited to chalk and acid volcanic rocks.

As the principal speaker has said, it is common practice to relate reservoir feasibility to rock type and condition and, on this basis, chalk sites have in the past been avoided as a matter of principle. In the U.K. there are no reservoirs in chalk to my knowledge, though one site is currently being investigated at Great Bradley in East Anglia. Much of this site is mantled by a blanket of boulder clay in places over 100 ft thick—the reason for its selection in the first place. In Cyprus, however, two reservoirs have been completed in the last five years in chalk valleys without the benefit of low permeability blankets. The dams are Polemidhia, 147 ft high, completed in 1965 and Yermassoyia, height 136 ft completed in 1968 (Fig. 1). Currently several other sites are being investigated, including one on the largest river in the country, the Kouris River, for which the proposed height of dam is 300 ft. For reservoirs in chalk, the main geological defect is not the occurrence of large karstic voids, for caves are rare or absent, but the presence of fissures which have been widened by solution. Groundwater conditions at sites generally fall in the main speaker's category 3 i.e. both the water
Engineering geology of the Turlough Hill pumped storage scheme
Authors: Knill John Lawrence
Published: November 2007

The Turlough Hill Pumped Storage Scheme has been constructed in the Leinster Granite some 40 km south of Dublin. The upper reservoir has been partially excavated on the summit of Turlough Hill and water can be discharged through an inclined tunnel into the underground power station and to the lower reservoir of Lough Nahanagan. The geological conditions at the site are outlined with particular reference to the rock properties and the location of the underground works.
Geology of motorways and the role of the Institute of Geological Sciences
Authors: Evans Wyndham Bowen
Published: November 2007

T
he
I
nstitute of
G
eological
S
ciences
is increasingly being asked to provide geological information along the lines of proposed motorways and major road improvements. It is rare, however, for such requests to be received before the line survey is completed, as was suggested in the then Ministry of Transport's Technical Memorandum T1/67. Consequently, advice tends to be limited to comment on likely difficulties along a route already established. This procedure works well in areas where geological sequences and structures are simple and consequently where geological factors are greatly outweighed by social factors. As motorways push into more difficult geological terrain, however, geological factors become increasingly more significant and an early approach to the Institute correspondingly more desirable.

It is general for the Institute to re-survey proposed road lines on request and bring older mapping up to modern standards. Moreover, collection of geological data in any regional study is necessarily selective and by up-dating the mapping with a specific project in mind, observations pertinent to that project can be made that might otherwise be considered too time-consuming to be justifiable, and the less obvious implications of the mapping can be clarified.

This sort of work can clearly be best done by the Institute with its pool of experienced field staff and its comprehensive back-up facilities. In contrast, many of the problems that arise during construction are essentially local ones and could be dealt with adequately by a site geologist using the Institute staff only where necessary. If geology is to be properly used at this stage some such arrangement must be made, for the field staff of the Institute is not large enough to deal with such matters on a general basis.

However close co-operation is between geologists and engineers, there is still a significant difference in approach between the two disciplines. The engineer requires quantification of rock properties so that he can calculate the effects of the interplay between his constructions and his site; the geologist doubts the validity of many such quantifications, at least in non-isotropic material intersected by a variety of differently inclined weakness planes, and would prefer to use an empirical approach, anticipating likely results by studying the history of comparable constructions in similar geological environments. To do this properly much more geological research is needed into the stability of natural slopes and established cuttings and embankments, whether or not these have histories of failure, and into devising with the engineer effective experiments on
in situ
rocks. In any such work the field staff of the Institute should be fully involved, so that the results obtained can help in making its primary route assessments more meaningful to the engineer.
Road Note 29: Revision
Authors: Thompson P. D.
Published: November 2007

Mr P. D. Thompson of the Road Research Laboratory, Ministry of the Environment introduced the Third Edition of Road Note 29 (
Road Research Laboratory 1970
) and discussed the main design recommendations.

Road Note No. 29 was first published in 1960 to provide a guide to the structural design of roads carrying medium and heavy traffic. The 1965 revision widened the scope to include lightly trafficked roads, such as those used in housing estates. Otherwise only relatively minor changes were made to the earlier edition.

Since 1960 the annual expenditure on the construction of new roads has increased fourfold. This alone provides sufficient reason for a detailed re-examination of all the recommendations given in the last edition. The growth rate of commerical traffic on many of the roads recently built has proved to be more than the 4 per cent annum allowed for 10 years ago; this means that there are on some roads daily flows of commerical traffic already exceeding the 6000-8000 vehicles that the original drafting committee had in mind as a maximum after 20 years. The size of the commerical vehicles in use has also tended to increase, and this has resulted in a greater proportion of heavier axle loads.

The present revision was drawn up within the Ministry of Transport in close consultation with a Panel set up by the Laboratory's Research Committee on Design and Construction. The Panel included county surveyors and consulting engineers.

This note deals solely with the construction of new roads and not
The relation of soil structure to the engineering geology of clay soil
Authors: Barden Laing
Published: November 2007

The microstructure of a number of undisturbed clays has been studied in the scanning electron microscope. These clays represent well known deposits from various parts of the world and can be classified under the following groupings: post-glacial marine clays, post-glacial brackish and freshwater clays, overconsolidated stiff fissured clays, and collapsing partly saturated soils. The object of the study is to relate the geological history of the soil to the observed engineering behaviour. It is seen that in general the most important factor governing microstructure is the chemical and physical environment obtaining during deposition, although the conditions resulting in flocculation and dispersion during natural sedimentation are not yet fully understood. Subsequent stress changes and weathering play an important role in modifying the microstructure, and particularly in developing macro-structural features such as fissures. In certain soils it is this macrostructure which dominates engineering behaviour in the mass; but in many cases such as sensitive clays and collapsing soil it is the microstructure which provides the important features.
Tunnels for roads and motorways
Authors: Wood Alan Marshall Muir
Published: November 2007

Geology is an important determinant affecting the planning, design and construction of a road tunnel. A road tunnel has to satisfy certain geometrical criteria and the achievement of the best economic route for a tunnel may be a complex operation, where the related geology offers any considerable choice.
In this paper examples are given of the principal characteristics of three recent road tunnels in Britain, explaining the degree to which the wide variations in tunnelling cost depends upon the nature of the ground.

It has generally been assumed that, where topography so allows, a road may be set underground by cut-and-cover construction at less cost than in a bored tunnel. In ground particularly favourable for economic tunnelling this is no longer necessarily true on direct engineering costs and, in an urban setting, other indirect costs tend to favour the case for a bored tunnel. Reference is made to the pattern of variations of cost with depth below surface for each of these types of tunnel.

The site investigations for a tunnel should be designed to determine the properties of the ground relevant to the selection of tunnelling method and the estimation of constructional difficulties. A highly mechanised system of tunnelling is particularly sensitive to geological variation and calls for an appropriate effort to eliminate, within reasonable limits, the risk of encountering an insuperable or disproportionately costly difficulty.

The problem of tunnel design relates directly to the competence of the ground. The concept of a
competence factor
is introduced in this respect. In soft ground, a principal problem is one of the adequacy of immediate support. In somewhat more competent ground, the extent of the need for immediate support depends on the knowledge of the stress/strain characteristics of the ground. For competent rock, the main problem concerns the means for determining the behaviour of the ground en masse. The method of excavation is also a factor affecting the behaviour of the rock around a tunnel.

Over the last 15 years or so there has been considerable experience in the use of rock bolts and shotcrete in providing support to the rock as an alternative to more traditional methods. The behaviour of such expedients is discussed in relation to the nature of the rock and of its discontinuities.

In soft ground, surface settlement may be important in determining the scheme for an urban tunnel. Settlement is not only largely dependent on the system of tunnelling but also upon the use of special expedients in relation to tunnelling in poor ground.
Foundation problems of motorway construction
Authors: Rogers Samuel Harry
Published: November 2007

In presenting a broad review of motorway foundation problems, the paper deals not only with bridges and other structural works but also with embankment and carriageway construction. The site investigation requirements are indicated and the design processes outlined. Reference is made to mining and the special difficulties encountered where motorways are located through the coalfields.

Illustrations of design and construction problems are given from various motorways in England and Wales.
Some observations on swallow holes and mines in the Chalk
Authors: West Graham , Dumbleton Michael John
Published: November 2007

The paper records some observations on swallow holes and mines in the Chalk and their effects on road construction, drawing examples from recent motorway construction for the M4 and M40 in Berkshire and Buckinghamshire. The forms and modes of origin of swallow holes are discussed and it is shown that percolation of rainwater can dissolve enough chalk to account for the formation of the smaller examples. Besides ground survey, air photographs are effective for locating swallow holes having surface expression of some kind, but no method has so far been generally successful in detecting those that have no surface expression. The engineering significance of swallow holes is the necessity of securing carriageways and bridges against possible subsidence caused by them. Various methods that have been used are mentioned and it is suggested that in areas at risk the completed road should be kept under surveillance against the appearance of new swallow holes. The paper concludes with an account of the discovery and inspection of an old unrecorded mine in the Chalk and the engineering measures that were taken to deal with it.
The geotechnical characteristics of a spoil heap at Yorkshire Main Colliery
Authors: Taylor Roy Kenneth , Spears David Alan
Published: November 2007

The physical and mechanical properties of 100 mm samples extracted from two boreholes through a spoil heap at Yorkshire Main Colliery are considered in order to determine whether or not degradation is taking place within the body of the heap. There is evidence that the aerial ropeway tip evolved in three phases and that the small variations in material properties are more readily attributable to these stages of development, rather than being a consequence of systematic degradation with the age of the spoil. Statistical treatment of consolidated-drained triaxial data and comparison with ‘fabricated’ samples (made up in the laboratory) of unweathered parental rock-types from underground imply that the shear strength of the tip samples is not changing with time. The zone of instability within which superficial movements can occur is considered to be of the same order as the depth of the erosional run-off channels, namely 3 m. Permeability tests, together with the chemistry of the groundwater show that there is restricted water movement through the body of the tip. The detailed nature of the investigations has facilitated certain preliminary conclusions to be drawn about the representability of samples.
The hydrological and electrical anisotropy of the Bunter Sandstssone of Northwest Lancashire
Authors: Barker Ronald David , Worthington Paul Francis
Published: November 2007

Investigations of horizontally and vertically oriented specimens have indicated a distinct anisotropy of intergranular permeability and apparent formation resistivity factor, although true formation factor seems virtually isotropic. It is suggested that this is the result of a preferred orientation of conducting minerals. There is, therefore, a need for caution in quantitative electrical surveys for groundwater in these formations.
Weathered granite at the Turlough Hill pumped storage scheme, Co. Wicklow, Ireland
Authors: Kennan PÁdhraig S.
Published: November 2007

Unsound weathered granite presented engineering problems during construction of the Turlough Hill Pumped Storage Scheme. Some geological properties of the rock are described and a mode of origin outlined. An empirical means of predicting, during reconnaissance investigations, potential occurrences of similar rock to considerable depths is suggested.
A Study of the strength, compressibility, and density trends within the chalk of South East England
Authors: Carter Paul G. , Mallard David J.
Published: November 2007

The voids ratio, compressibility, and strength characteristics of intact chalk samples collected from exposures encountered along several traverses across the outcrop of the Chalk in South-east England are described. The results are shown to be related to the age of the Chalk from which the samples were collected, with the younger Upper Chalk samples having lower density and strength characteristics than samples collected from the older Lower Chalk. These relationships are shown to be uniform for the majority of the Chalk outcrop in South-east England, with the Norfolk area showing a marked disparity with the remainder of the outcrop.
Engineering geological mapping for civil engineering practice in the United Kingdom
Authors: Dearman William Robert , Fookes Peter George
Published: November 2007

A brief review of past British practice in engineering geological mapping is given. The paper follows the recommendations given in the Report on the Preparation of Maps and Plans in Terms of Engineering Geology prepared by a Working Party of the Engineering Group of the Geological Society.

A major division is made into small-scale maps generalised in content and made for regional and planning purposes, and large-scale plans relatively detailed in content and made for specific engineering purposes. Examples from present practice are illustrated and discussed. These include engineering geological maps, and engineering geological plans made at the reconnaissance, site investigation and construction stages of a project. Geotechnical plans, presenting a single engineering design parameter or a combination of a limited number of parameters, are illustrated for both the reconnaissance and site investigation stages of actual engineering projects.

After considering research in engineering geological mapping, likely future trends and desirable developments are discussed. It is considered that increasing use will be made of (i) engineering geomorphological mapping at the reconnaissance stage of investigation; (ii) site investigation mapping as part of conventional site investigations; (iii) geotechnical plan mapping for specific investigations and designs; (iv) engineering geological maps and plans specifically for use in urban situations by planners concerned with urban development.
Debris flows originating from soil slips during rainstorms in Southern California
Authors: Campbell R. H.
Published: November 2007

Debris flows generated during rainstorms present a greater risk of death and injury to southern California residents than all other kinds of slope failure combined. During the years 1962-1971, twenty-three people in the greater Los Angeles area died from being buried or struck by debris flows, all of which probably originated as soil slips. Soil slips and debris flows are recurring major natural geomorphological processes in the region.

Soil slips are reconstituted into debris flows when the initial movement (sliding failure) of slabs of soil and wedges of ravine fill causes remoulding of the saturated moving mass into viscous, debris-laden mud, which then flows down available drainage courses. This change of state results in a marked reduction in resistance to shear, permitting masses to accelerate down the same slopes on which, only moments earlier, the slabs of soil mantle had barely overcome the resistance to sliding. Many flows reach avalanche speeds and do not begin to deposit significant amounts of detritus until they reach lower gradients far from their sources. The deposits form steep ‘alluvial’ fans at the mouths of short, steep drainage basins tributary to broad valleys, and form debris trains in and along narrow trunk canyons below the mouths of short, steep tributaries.

The exceptional storm period of January 18th to 26th, 1969, was accompanied by thousands of soil slips and provided an unusual opportunity to determine the times of occurrence of numerous debris flows, establish their origin from soil slips, and compare the times of those events with rainfall records from an extensive network of continuously recording rain gauges and a sequential set of radar weather maps. An empirical association between soil slips and rainfall suggests that a 10 inch antecedent rainfall is required to bring most of the colluvial soil of the area to field capacity, and 0.25 inch-per-hour is the minimum rate at which surface infiltration exceeds subsoil drainage for most of the colluvial soils of the area so that pore pressures are raised in a zone above the less permeable parent materials. Soil moisture of this level also appears to be sufficient so that most of the colluvial soils of the area will become at least partly liquid when disturbed.
Spring mudflows at Wrightwood, Southern California
Authors: Morton D. M. , Campbell R. H.
Published: November 2007

The Wrightwood area in the San Gabriel Mountains of southern California is known as a site of recurring mudflow activity. The community of Wrightwood is built on the coalesced fans of Sheep, Acorn and Heath Creeks, and the fan deposits are probably chiefly of mudflow origin. Historically, mudflows there have been observed in association with three climatic conditions: (1) short period of high-intensity rainfall during the summer dry season (thunderstorms); (2) periods of heavy rainfall during the October-March winter season, when most of the year's rain and snow fall; and (3) thaw of the winter snow pack. The mudflow activity associated with heavy rainfall has generally been of only a few hours or at most a few days duration. Mudflow activity associated with spring thaw has been of longer duration, as much as several weeks. At various times in the past, mudflows generated by all three conditions have inundated homes and highways in the Wrightwood area, which is now defended by a flood control levee system.

During May and June, 1969 the rapid melting of a heavy snow pack resulted in a 40-day period of mudflow activity in Heath Creek. All flows originated in the steep upper reaches of Heath Creek, where steep ravines are incised in the toe of a large active landslide. Direct observation by the authors showed that flows formed when small masses of debris fell or slid from the surface of the landslide mass into the steep channel. Some of the masses were fluid enough to continue downstream without interruption; others stopped in the channel until remobilized by added melt water or the passage of a mudflow from a higher altitude. Both processes resulted in discrete ‘slugs’ which continued down the steep ravine, through an allu-viated canyon, to a fan where most of the debris was deposited.

The activity may be described as a spring mudflow cycle, within which three stages were observed in a gradational sequence. A waxing stage began with sporadic short-duration mudflows, during which the lower alluviated canyon floor of Heath Creek was aggraded. A climactic stage of larger mudflows at more frequent intervals and of longer duration was characterized by the incision of a single, narrow, U-shaped channel in the alluviated canyon floor, and transportation of debris as much as 2 miles (3.2 km) from the source. A waning stage followed as meltwater supply decreased; short-duration flows backfilled the U-shaped channel and spilled over the banks, again aggrading the alluviated canyon floor.
The application of geophysical methods in the exploration and development of Sandstone aquifers
Authors: Worthington Paul F. , Griffiths Donald H.
Published: November 2007

Procedures are suggested for the optimum use of electrical resistivity and seismic techniques in determining hydraulic conductivity and transmissivity within sandstone aquifers. The object is to improve the siting of abstraction boreholes. The primary emphasis is placed upon electrical methods for studying consolidated formations from which there has been good core recovery, and within which intergranular flow is important. The recommendations are based upon experience gained during hydrogeological and geophysical investigations of the Bunter Sandstone in the Fylde area of northwest Lancashire, England.
Investigation of a coastal landslip at Charmouth, Dorset
Authors: Denness Bruce , Conway Bernard Walford , McCann David Michael , Grainger Peter
Published: November 2007

The Dorset coast is an area with a long history of landslide activity and coastal erosion. Geologically the area is composed of the clays, mudstones and limestones of several divisions of the Lower Jurassic (Lower Lias) which are overlain unconformably by Cretaceous clays and sands (Gault and Upper Greensand.) Areas of serious instability appear to occur in close association with naturally occurring reservoirs of ground water, of which Black Ven at Char-mouth is a good example.

Problems connected with a small coastal landslip near a private housing estate at Char-mouth were studied and shown to be related to a Pleistocene mudflow. The main purpose of the investigation was to suggest remedial works but the subsidiary aim, forming the theme of this paper, was to assess the usefulness of shallow depth geophysical and geotechnical methods not normally used in instability studies.
Factors affecting the detection of slope instability with air photographs in an area near Sevenoaks, Kent
Authors: Norman John Wakelin , Leibowitz Theodor Herzl , Fookes Peter George
Published: November 2007

Twenty-six sets of air photographs were used to test the best photographic conditions for detecting landslips, mainly old periglacial solifluction movement, along a ten mile stretch of sloping ground. A total of 141 old landslip features were detected and many varied in clarity on the different photographs, some being hard or impossible to detect on foot without the aid of air photographs. The repeated images of the same landslips on different sets of photographs produced a total of 2 715 photo-features for statistical studies.

Analysis of the results showed that the best technical photographic conditions for detecting such features are the use of infra red colour film, stereoscopic photography with a short focal length lens, a nominal photographic scale of about 1:5 000, and a sun angle that casts local but not very extensive shadows. It is considered that automatic dodging can both enhance and suppress vital information on images, and that the best seasons for photography are likely to be spring and late summer to early autumn.
Some unusual structures in the river gravels of the Thames Basin
Authors: Wakeling T. R. M. , Jennings R. A. J.
Published: November 2007

Four sites in the London area are described where sandy gravel overlies London Clay. On two of these sites the unexpected occurrence of deep steep-sided natural depressions in the surface of the London Clay gave rise to delays during the construction of civil engineering works. On the other two the depressions were discovered during the initial site investigations and appropriate measures for dealing with them were taken in good time.
The application of air-flush rotary percussion drilling techniques in site investigation
Authors: Honer P. C. , Sherrell F. W.
Published: November 2007

The technique of drilling boreholes using air-flush rotary-percussive drilling rigs is widely used in the quarrying and civil engineering industries, but its application in site investigation does not appear to have been appreciated. It involves the drilling of boreholes under controlled conditions, using a rotary-percussive drill, and measuring the rate of penetration. Systematic sampling of the drilling flushings and observation of the drilling characteristics enable an indentification of the rock type to be made, as well as an interpretation of some important aspects of its geotechnical behaviour. Although the technique does not provide a continuous visual record of the intact material drilled, it has been extensively and economically applied in South-west England, particularly in the search for cavities in rocks and the depths to, and quality of, bedrock and variations in the properties of some types of soils. The interpretation of the results is further improved if the results of some core-drilled or shell-and-auger drilled boreholes are available for direct comparison, correlation and “calibration”. The technique can also be applied in cases where the boreholes are drilled for other purposes, such as grouting, rock anchoring and blast-hole drilling, in order to supplement knowledge of the ground conditions.
Interborehole acoustic measurements in site investigation
Authors: Grainger Peter , McCann David M.
Published: November 2007

Interborehole acoustic measurements are made by transmitting a pulse of sound energy from one borehole to another. Analysis of the recorded signals can provide useful information on ground conditions between and beneath the boreholes. This includes the location of boundaries between different rock and soil types, and an assessment of geotechnical properties in certain cases. A sparker source of energy has been developed for use in boreholes, giving a repetitive pulse shape. The received signal may contain direct, refracted and reflected arrivals, which can be timed. These times are converted to apparent velocities and a vertical scan of two boreholes presented as an apparent velocity versus depth curve.

Two case histories from the Dinorwic hydro-electric scheme in North Wales and from Whatley Quarry near Frome in Somerset, illustrate the nature of the interpretation process, and the quality and distribution of the additional geological data that can be achieved. Interborehole scanning has certain advantages over conventional surface seismic refraction; for example, in the detection of low velocity layers at depth. It does of course have its limitations, in the theoretical, interpretational and the practical senses. With these limitations minimized, interborehole acoustic measurements can be a very useful addition to site investigation.
Discussion by J. N. Hutchinson
Authors: Hutchinson J. N.
Published: November 2007

In 1958–59, 25 loading tests were made at Khorramshahr on concrete friction piles driven in connection with extensions to the port, where the ground consists of deep deposits of soft to medium estuarine silty clays. Thirteen of the piles tested had been coated with a thin layer of bitumen as a protection against attack by soil acids: the remaining twelve piles were uncoated.

The loading tests showed that the shaft bearing capacities of the coated piles were between 30 and 80 percent lower than those of equivalent uncoated piles. A further, most interesting, finding was that the bearing capacity of the coated piles fluctuated seasonally (Fig. 1). This fluctuation was shown to be consistent in phase and magnitude with that which could be predicted from the seasonal fluctuation in ground temperatures and the temperature-viscosity characteristics of the bitumen used. Full details of the work are given in Hutchinson & Jensen (1968).
Engineering geological case study of the site investigation and design of a major trunk road cutting in Carboniferous rocks
Authors: Buist D. S , Burnett A. D. , Sanders M. K.
Published: November 2007

The 7.1 km dual two-lane Unstone-Dronfield By-Pass, Derbyshire, first opened to traffic in 1975, incorporates a 30 m deep rock cut at Monk Wood, excavated in strata of Lower Coal Measures age. Cuttings in similar geological settings elsewhere had resulted in mass slide failures and the measures adopted at Monk Wood to avoid a similar problem are described. The site was complicated by the presence of extensive old workings for coal and ironstone; their treatment is discussed.
Discussion on ‘Peterhead Power Station cooling water intake tunnel: An engineering case study’ by
Authors: Barton N.
Published: November 2007

The authors' comparison of site investigation predictions and actual tunnelling conditions encountered at 50 m depth in partly weathered granite make interesting reading. In particular, it is encouraging to note the increasing use of classification systems as an aid to tunnel support design decisions. The authors state that ‘the support system generally used in the tunnel varied from that actually recommended in the site investigation report but lay within the range of alternatives suggested by Bieniawski’ (Bieniawski 1973). The contractor in fact elected to use steel ribs as primary (temporary) support ‘in distinct preference to the rather more sophisticated roof bolting with sprayed concrete’.

Application of Bieniawski (1973) had in fact shown that suitable
primary
support for the 4.6 m span tunnel should be found among the following alternatives:

(i) B l-1.5m + S(
mr
)30mm

(ii) S 100 mm (crown), 50 mm (sides) (with occasional mesh or bolts as required)

(iii) light steel sets 1.5 to 2.0 m spacing
where S = shotcrete, (
mr
) = mesh reinforcement, B = rock bolts of given spacing.

The
final
300 mm thick concrete lining cast to a finished diameter of 4.0 m was presumably dictated by other requirements, since the authors state that ‘the rock together with its primary support system (should) provide the principal structural strength of the tunnel whether empty and at atmospheric pressure or full of water under tidal pressure’.
With the above requirement in mind it is reasonable to apply the NGI Q-system of classification (Barton
et al
. 1974, 1975)
The collapse of the Dale Dyke dam in retrospect
Authors: Binnie G. M.
Published: November 2007

Introduction

The original Dale Dyke dam situated 9 miles west of Sheffield on the River Loxley, a tributary of the River Don, collapsed suddenly on the 11th March, 1864. Nearly 250 people lost their lives and there was considerable damage to property, including some in the city itself.
Amey (1974)
gives a very readable account of the disaster and its aftermath.

Expert opinion at the time was divided as to the cause of the collapse of the dam, sometimes referred to by contemporary writers as the Bradfield dam from its location near the village of Bradfield in Bradfield Dale. One school of thought maintained that it was due to leakage from pipes beneath the embankment and consequential erosion, and another that it was due to a landslide which encroached upon the downstream toe of the embankment. More than 100 years have passed since these and other theories on the cause of the breach were put forward. In the light of the experience that has been gained since then in the behaviour of earth dams, an attempt has been made to draw fresh conclusions from a review of the evidence.

Contemporary sources

An inquest on the disaster was held on 24th and 25th March 1864; a verbatim account is given in a contemporary Parliamentary report (
Sheffield Waterworks Bill 1864
). Both the Sheffield Waterworks Company, who owned the reservoir, and the Sheffield Corporation, who wished to buy out the waterworks company, engaged consulting engineers to investigate the failure and their reports are available
Discussion on ‘A numerical model for the perdiction of long term well yield in an unconfined chalk aquifer’ by B. J. Connorton & R. N. Reed
Authors: Puri S.
Published: November 2007

Connorton & Reed's paper on the use of a radial flow model is an interesting addition to the knowledge of chalk aquifers and their hydraulic response. There are, however, a number of points that arise and need comment.

The first of these is concerned with the use of a radial flow concept in aquifers that are recognised to have a marked anisotropy. The authors have dismissed this by stating that within a short distance of the well (up to 100 m) radial symmetry can be assumed. During studies of a number of pumping tests in the Middle Chalk in east Kent, which had the good fortune of having observation wells located at right angles to the pumped well, I noticed that radial symmetry of aquifer parameters almost never occurs, even at distances sis near as 50 m.

The second comment relates to the use of ‘saturated thickness’ and the associated corrections for its decrease. Assigning a value related to the frequency of fissuring implies complete absence of pore water, which plays an important role in the aquifer's hydraulic response. Owen & Robinson (1978) in the same study area suggest that these thicknesses range from 45 to 60 m, while the authors have implied it to be 100 m as shown by their use of adjusted T values for their modelling.

The complexities involved indicate that the best way to understand the interactions between various parameters is to use a simple model, such as the radial model. One of the greatest
Porewater composition in the unsaturated zone of the Chalk, with particular reference to nitrates
Authors: Spears D. A.
Published: November 2007

Thirty-seven samples of Upper Chalk from a borehole in the unsaturated zone near Manston in Kent were analysed for major elements and the mineralogy was determined. Porewaters were extracted and analysed for major cations and anions. Changes due to infiltrating water were not detected in the whole-rock analyses, but the porewater analyses generally show a decrease in concentration with increasing depth. The cause of the variations and the origin of the elements are discussed.
Morphological mapping in the Axmouth-Lyme Regis Undercliffs, Devon
Authors: Pitts J.
Published: November 2007

Morphological mapping has proved extremely useful in a renowned area of coastal landslipping.

The undercliffs form a coastal strip nearly six miles long, and up to 500 m in width. The antiquity (possibly late Pleistocene in part), and the large scale of much of the landslipping have assisted in the development of a mature, luxuriant vegetation cover, which masks much of the ground detail. However, the main back and side scars have often remained clear from the air, enabling photogrammetry to be used to produce base maps at a scale of 1:2500. Ground details where added to the base maps from fieldwork clearly reveal the patterns of mass movement. Examples of the final geomorphological maps are presented.

Some 19th century interpretations of the mechanisms of landslipping indicate the advantages of observing the features in a fresh, lightly vegetated state. The present programme of morphological mapping has, hopefully, revealed a sufficient quantity of the detail to enable a reassessment of the area in the light of modern theory. Detailed morphological mapping is also presented as a site investigation technique of considerable merit in areas of difficult access and terrain, or in protected areas.
Problems of engineering-geomorphological mapping on impermeable surface materials and in karst regions
Authors: Lang S.
Published: November 2007

The author outlines the type of information which should be presented on engineering-geomorphological maps, and stresses the need to show the relationship between this data and the possibility of natural catastrophes. For example, it is proposed that a system of maps covering areas where there is a high probability of landslipping should be devised, with priority to be given to populated tropical and equatorial regions. The mapping of other ‘problem’ areas (e.g. arid, polar, and karst regions) is also discussed. However, it is concluded that, in all areas, an overall evaluation of climatic, morphological, and lithological factors is essential for engineering-geomorphological mapping.
Engineering geomorphological mapping as a technique to elucidate areas of superficial structures; with examples from the Bath area of the south Cotswolds
Authors: Hawkins A. B. , Privett K. D.
Published: November 2007

From the literature and the geological maps it is known that superficial structures occur extensively associated with the Jurassic strata in the south Cotswolds. There is some discrepancy in the representation of superficial structures on the small-scale geological maps (1:63,360 and 1:50,000 scales).

Examples from the Bath area have been selected and engineering geomorphological maps of some superficial structures are presented. It is concluded that valley bulges and cambers are difficult to delimit using this technique but landslips, especially the more recent, large-scale ones, and mudflows can often be clearly depicted. An important consideration is the subsequent ‘smoothing’ of natural features by hillwash or intensive agriculture and associated ploughing. It is concluded that this form of mapping is no substitute either for geological mapping or for a proper site investigation; it can, however, add valuable data.
The representation of the morphology of slopes on engineering geomorphological maps with special reference to slope morphometry
Authors: Kertész A.
Published: November 2007

Engineering geomorphological maps are expected to represent the characteristics of surface morphology in relation to economic and technical planning in a concise and easily understandable form. The most satisfactory means of attaining this objective is to use morphometric methods for the characterization of relief. Morphometric methods include quantitative description of the relief.

Hungarian engineering geomorphological maps indicate the stability of slopes, the nature, intensity, and direction of slope processes, as well as the delineation of slope categories. Among these factors only the latter gives quantitative morphometric information, the others being qualitative classifications. This paper presents methods of representing the above properties and reviews morphometric methods of representing slopes, such as:

the values of average and extreme slope angles, which are equally important for engineering applications. Among slope maps those representing
slope categories
are particularly successful.

slope morphology maps show the slope direction, the average slope angle and the slope form (convex, concave, rectilinear, and compound) within the pattern of the drainage network

isotangent maps give information on the surface gradients

relative relief maps represent the maximum relative level differences relating to territorial units.

These techniques complement engineering geomorphological maps; some of the information can be transferred to general engineering geomorphological maps. But, most importantly they are used in the precise and quantitative definition of certain types of relief.
Beach and dune interactions during storm conditions
Authors: Leatherman S. P.
Published: November 2007

Recently, coastal investigators have questioned the function of barrier dunes during storm conditions. Dunes were believed to interfere with swash processes by constricting the beach profile over which the energy must be dissipated. Also, some researchers believed that dunes act as seawalls and reflect a significant portion of the incident wave energy. Either of these two possible effects would result in accelerated beach erosion. Considering the worldwide importance of coastal dunes as a protective barrier system, it was paramount to gather information by which to further examine these hypotheses. In this paper, the author reports field data collected to date during storm conditions and summarizes the pertinent laboratory investigations. Finally, a new model is conceptualized regarding the functioning of barrier dunes during storms versus flow dissipation by overwash.
The Portavadie dry dock, west Scotland: a case history of the geotechnical aspects of its construction
Authors: Clark A. R. , Hawkins A. B. , Gush W. J.
Published: November 2007

The paper discusses the construction of a dry dock in western Scotland designed for the fabrication of offshore concrete oil production platforms. The project involved the excavation of some 830 000 m
3
of soft material and rock from a tidal inlet to a base level between 11 and 13 m below Chart Datum. The construction period was limited through the necessity to meet a climatic window for float out. The progress achieved and the organizational relationships of the project are described.

The site investigations prior to commencement of the site work were limited. These and the subsequent investigations carried out during the course of the works are described. The authors also discuss methods of construction, and show how certain aspects of these and the original designs were modified as the work proceeded.