bluuebunny/crossref_metadata_2025 huggingface dataset:
Delineating concealed faults and shallow subsurface geology along the Wasatch Front, Utah, USA, by integrating geophysical and trench data
Authors: Benson Alvin K. , Mustoe Nathan Brett
Published: November 2007

Planning and development along the Wasatch front must compensate for the geological hazards associated with faulting. Studies show that future ruptures will probably occur along already existing zones of weakness. Although any surface faults can be detected by surficial geological mapping others have no visible expression and can only be located by subsurface investigations. Geophysical methods, such as seismic refraction, gravity, magnetic, and radar can be integrated with geotechnical engineering methods such as drilling and trenching to obtain a better understanding of the subsurface geology at a specific site.

Seismic refraction, gravity and magnetic surveys conducted near Provo, Utah along the Wasatch Mountain front have helped delineate shallow, concealed faulting. The reduced, modelled gravity and magnetic data typically correlate well with the refraction depth sections generated using the General Reciprocal Method (GRM). Field observations coupled with the geophysical data facilitated the identification of a number of probable faults along Rock Canyon Road, allowing an estimate to be made of the magnitude and direction of throw on the fault.

A normal fault associated with a prominent north–south scarp near Rock Canyon Road was chosen for a case study. This fault scarp was later trenched by the Utah Geological and Mineral Survey (UGMS) and provided a direct comparison with the geophysical data sets. As all the data sets at this site correlate well with the subsurface geology, confidence is increased in interpreting other parts of the line. The characteristics of subsurface deformation can be used to gain a better understanding of the potential for surface rupture at a site and thereby in planning and site development and in devising remedial measures to mitigate the effects of earthquakes in populated areas.
The significance of faults for the Afulilo hydro scheme in Upolu, Western Samoa
Authors: Gudge H. J. , Hawkins A. B.
Published: November 2007

The geologically young Samoan Islands are situated in a seismically active area in the Pacific Ocean, at the northern end of the Kermadec-Tonga Trench. The paper discusses two faults not shown on the 1: 100 000 geological maps of the area. One of the faults, trending northwest/southeast, has been postulated as passing through the Afulilo dam site. The other fault trends northeast/southwest, displacing the line of the recent volcanic cones by up to 2.5 km. Any movement along this fault could affect the integrity of the hydroelectric powerhouse and a possible future intake structure.
The Kaiapit Landslide: events and mechanisms
Authors: Peart M.
Published: November 2007

The landslide at Kaiapit occurred on the morning of 6 September 1988 in the Finisterre Range of Papua New Guinea and resulted in 74 fatalities. The landslide involved an estimated 2 km
3
of debris which covered an area of 11.4 km
2
and left a back-scarp some 1600 m high. The debris ran out in three flows for approximately 6 km in 5 minutes and velocities of 180km/h have been estimated. No single cause for the initiation of the landslide has been determined. It is felt that its location in a tectonically and seismically active region, the tropical climate and an inherently weak rock mass were fundamental contributary factors. The failure mechanisms are considered to have been massive planar slides. The debris assumed a final angle of rest of 6°; this may be explained by a combination of the concepts of acoustic fluidization and air entrapment. The landslide debris resulted in the formation of four dams, which had all breached within eight months of the event. Active erosion of the debris is resulting in the aggrading of river bed levels in the area.
Hydrogeological investigation of a fault in clay
Authors: Sen M. A. , Abbott M. A. W.
Published: November 2007

Measurements of groundwater head and hydraulic conductivity have been made around a fault in the Oxford Clay in order to examine the effect of a fault on the hydraulic properties of a clay and on groundwater flow. Pulse tests performed in the clays gave values of hydraulic conductivity ranging from 5 × 10
-12
to 2 × 10
-8
ms
-1
. Although showing some overlap with the unfaulted clays, the hydraulic conductivity in the fault zone appears to be enhanced with respect to the adjacent unfaulted clays by up to one or two orders of magnitude. The groundwater heads in the mudrocks/clays are high compared with those in the underlying aquifers and appear to be relics from the period before major groundwater abstraction. Some outline numerical modelling suggested that both changes in fault geometry and varying fault properties could be invoked to explain adequately the measured head profiles using the traditional assumptions of Darcian flow. However, it is recognized that coupled flow processes may be of great significance in clay formations; in particular, the measured heads may result from hydraulic effects coupled with chemical and mechanical potentials.
The Channel Tunnel: geotechnical monitoring to breakthrough
Authors: Warren C. D. , Varley P. M.
Published: November 2007

The Channel Tunnel Project is one of the largest ground engineering projects currently being undertaken in the world. The scheme is being designed and built by Transmanche Link (TML), a consortium of British and French contractors for the client Eurotunnel (ET) and will provide a complete transportation system linking the UK with Continental Europe.

The rail link will be provided by two tunnels with their portals located at Castle Hill, north of Folkestone (UK) and Beussingue Farm, near Sangatte in France. Each tunnel is approximately 50 km long, of which 38 km is located under the seabed between Shakespeare Cliff and Sangatte (Fig. 1).

The system comprises two 7.6 m diameter running tunnels, 30 m apart, with a 4.8 m diameter service tunnel located centrally between them. For operational and safety reasons all three tunnels are connected by 3.3 m diameter transverse cross passages located at intervals of 375 m throughout the drive. In addition, 2 m diameter piston relief ducts pass between the running tunnels every 250 m. These will allow dissipation of the air pressure pulse in front of the train and thereby reduce aerodynamic drag.

At two points along the tunnel length i.e. km 27 and 45 approximately, there are large underground crossover chambers. These will allow trains to transfer between the running tunnels, for example whilst maintenance is being carried out in a particular section of tunnel.

The construction of the tunnels, crossover caverns, pumping stations and all ancillary works, involves the excavation, lining and ventilation
Lithological controls of mudrock durability
Authors: Dick J. C. , Shakoor A.
Published: November 2007

The effect of lithology on slake durability of 51 mudrock samples was investigated with the objective of developing a comprehensive durability classification. Grain size distribution, clay mineralogy, void ratio, micro-fracture frequency, Atterberg limits and scanning electron microscopy were used to characterize lithology, whereas second cycle slake durability index was used to measure durability. The mudrock samples were classified into five distinct lithologies that included 10 claystones, 18 mudstones, 12 shales, 5 siltstones and 6 argillites. In addition to clay content and presence of laminations, Atterberg limits were used to differentiate between these lithological classes.

The second cycle slake durability index was correlated with the lithological characteristics of each mudrock lithotype. The results indicate an exceptionally strong relation (r = -0.98) between the percentage of expanding clay minerals and slake durability index for claystones. Mudstones exhibit a strong relation (r = -0.94) between the ‘micro-fracture frequency index’ and slake durability index. A strong relation (r = -0.98) between void ratio and slake durability index is indicated for shales. These results underscore the importance of distinguishing mudrock lithology in durability investigations.
Natural mineral waters: a Scottish perspective
Authors: Robins N. S. , Ferry J. M.
Published: November 2007

Natural mineral waters are weakly to moderately mineralized untreated groundwaters of which 18 of the 37 recognized in the UK are Scottish. Aquifers in Scotland are small and have local, relatively shallow groundwater flow paths. Travel times from recharge areas to these sources may be only a few days or weeks for upland sources and years or tens of years for lowland sources. The catchments of some sources are protected by controlled land use, others by the principle of good neighbours. The hydrogeological criteria for the recognition of natural mineral waters are discussed.
Selecting appropriate numbers of increments for bulk samples of aggregates
Authors: Pike D. C.
Published: November 2007

The British Standard for testing aggregates, BS 812:1989, requires at least ten scoopfuls of sand to be taken from any stockpile to obtain a representative bulk sample. This does not necessarily provide a representative sample, however, as the number of increments should be related to the variability of the batch being sampled. This paper describes trials in which increments were taken from stockpiles of sand and subjected to two tests: determination of fines content by washing and sieving and assessment by methylene blue titration of harmfulness of fines. It was found that the minimum number of increments required to provide a representative sample could be as low as two or as high as seventeen. The approach could be extended to other combinations of aggregate grades, test methods and specification limits.
A new approach to studying complete rock engineering problems
Authors: Hudson J. A. , Harrison J. P.
Published: November 2007

With the increasing sophistication of our interpretative techniques, numerical analysis and rock characterization schemes, it is becoming more important to base rock engineering design and the associated site investigation, construction and monitoring procedures on a coherent structural understanding of the complete rock engineering problem. This includes not only the primary mechanisms and parameters, but also the interactions between them. This paper outlines a novel approach to listing and presenting the rock mechanics and rock engineering parameters so that all the interactive or coupled mechanisms and terms can be identified. At its lowest level, this provides a useful checklist for a project; at higher levels, it can provide the logic behind the entire design procedures.
The material strength of sandstones of the Sherwood Sandstone Group of north Staffordshire with reference to microfabric
Authors: Yates P. G. J.
Published: November 2007

Sherwood Sandstone exhibits a wide and uncertain range of engineering behaviour. Laboratory test results are presented and show that the material may range from sand to moderately weak rock. Microfabric analysis suggests that depositional and diagenetic processes have as much an influence on this variability as does weathering. A means of estimating the material shear strength of the weakest zones of Sherwood Sandstone is proposed.
Limestone to dolomite to dedolomite conversion and its effect on rock strength: a case study
Authors: Williams D. M. , McNamara K.
Published: November 2007

A series of cores from Carboniferous rocks in Co. Donegal, Ireland, revealed the presence of limestones, dolomites and dedolomites beneath the Cliff Dam. The conversion of limestone to dolomite probably occurred early in the rock's history, assisted by the presence of evaporite minerals such as gypsum. The conversion of dolomite to dedolomite was probably a later event related to fault-assisted ingress of meteoric waters during uplift of the rock mass. The compressive strength of the limestone is considerably affected by both processes. In this case, the conversion of limestone to dolomite resulted in an approximately 20 0ecrease in compressive strength whilst the limestone to dolomite to dedolomite conversion resulted in a 75 0ecrease. Thin-section study may be necessary in such cases to distinguish dedolomites from their associated country rocks.
A semi-analytical model for borehole catchments and time-of-travel zones which incorporates recharge and aquifer boundaries
Authors: Lerner David N.
Published: November 2007

A new computer model to predict catchments and time-of-travel zones to boreholes is described. It takes account of spatially varying recharge which is not included in the most commonly used analytical solution. The model can also accommodate four arrangements of aquifer boundaries, two of which represent strip aquifers while the other two are rectangular. The bases of the model are new analytical solutions for the velocity components due to both recharge and pumping from boreholes. Boreholes in rectangular aquifers are modelled by the method of images. Examples show that taking account of recharge and boundaries gives significantly different results for catchment sizes and shapes from the analytical solution commonly used. The size of time-of-travel zones can be significantly smaller when recharge is taken into account. The main uses of the model will be in reconnaissance and sensitivity studies.
Level-determined groundwater sampling from open boreholes
Authors: Bishop Philip K. , Gosk Edmund , Burston Mark W. , Lerner David N.
Published: November 2007

An important aspect of any detailed groundwater quality investigation is determining the vertical distribution of pollutants. This may best be achieved by using permanent sampling systems installed in dedicated boreholes. However, the availability of open boreholes in the UK, coupled with the relative expense of installing dedicated systems, has increased the value of methods for obtaining level-determined samples from such boreholes. This paper presents a qualitative appraisal of three such methods, based on the use of portable pumps and packers, frequently combined with flow logging. The methods were tested in four open boreholes penetrating a multi-layered aquifer. In the most successful applications, vertical profiles of chlorinated hydrocarbon solvent concentrations were defined which were thought to be representative of those in the aquifer.
The hydrogeological use of thin sections: inexpensive estimates of groundwater flow and transport parameters
Authors: Younger P. L.
Published: November 2007

The techniques of petrological microscopy are seldom applied to hydrogeological problems although they allow the direct measurement of grain size, pore size and porosity, from which it is possible to estimate hydraulic conductivity, specific yield and solute retardation factors; information clearly valuable where direct measurement of these parameters is impossible. Further comparison of microscopically determined values with direct measurements provides a physical basis for the development of accurate conceptual models of the micro-scale processes which control groundwater flow and solute transport. During the development of a catchment—scale model of the hydrological effects of land use change, petrological microscopy was successfully used as a means of extending the database. In particular, hydraulic conductivities estimated from thin section observations showed a clear positive correlation with permeameter-derived hydraulic conductivities for the same samples.
High-resolution shallow seismology: history, principles and problems
Authors: King R. F.
Published: November 2007

High-resolution reflection surveys have been used in watercovered areas for some time, but only during the last decade has serious attention been paid to the development of survey techniques to give comparable results on land. These techniques are now becoming well established. This paper gives an outline of the principles of reflection seismology and of the particular problems that arise when the method is applied to depths of 200 m and less.
Better than drilling? Some shallow seismic reflection case histories
Authors: Hill Ian A.
Published: November 2007

Seismic surveys have been conducted at several sites within the UK with widely differing geological lithologies and structures. The equipment and field techniques are briefly reviewed. The case histories for selected sites are presented showing both the benefits and problems of the seismic survey and the geological interpretations. Lithologies surveyed include mudstone/sandstone sequences, lignite, gypsum beds and evaporites. As all these sites have either been drilled or excavated since the survey period, it is possible to compare the actual geology with the seismic interpretation. In most cases the seismic surveys have added to the previously assumed geological model and subsequent data have confirmed the seismic interpretations. On the basis of the data reported here it can be concluded that shallow reflection seismics (SRS) gives a combination of resolution and penetration not possible with other geophysical methods.
Examples of the application of shallow reflection surveys in The Netherlands
Authors: Meekes J. A. C.
Published: November 2007

Several case studies show the impact of acquisition parameters on the quality of the data in high-resolution seismic reflection experiments aimed at imaging unconsolidated sediments in The Netherlands. Buried sources and hydrophones yield the best quality data. Seismic sections of good quality and high resolution were obtained from which information on the seismostratigraphy and on the lateral changes can be derived.
Use of computers in the engineering geology of the urban renewal of London's docklands
Authors: Howland A. F.
Published: November 2007

A systematic collation of geotechnical information has given engineering geology an important role in the renewal of London's docklands. It has provided a ready source of information to other parties and allowed an improvement in the understanding of the regional engineering geology of the area. A microcomputer database, termed GEODASY, was devised specifically to store the data. This allowed for a projected 10 000 boreholes and holds both stratigraphic as well as field and laboratory test data. The data can be retrieved in a variety of formats. The basic output is a tabulated format which collates and unifies the presentation of the data. Other graphical output produces scaled plans or long sections while preprocessing by the system during enquiry gives
X-Y
plots allowing a high level of interpretation of the data. The approach could be similarly used wherever there is a strongly defined area of interest.
Treatment of expansive soils for reducing swell potential and increasing strength
Authors: Stamatopoulos A. C. , Christodoulias J. C. , Giannaros H. Ch.
Published: November 2007

The area 60 km northwest of Athens is underlain by swelling soils, mostly of the 'terra-rossa' type. Laboratory tests were performed in order to examine the effectiveness of various methods in alleviating the adverse results of seasonal swelling-shrinking especially in connection with roads and foundations of buildings. It was found that the order of effectiveness of additives was (i) 4% cement and 2% lime, (ii) 6% lime, (iii) about 6% cement, (iv) 6% polymer (polybutadiene) and (v) lime in the free water. It was also found that swelling can be reduced substantially by simple mechanical stabilization, i.e. surcharge and/or dissociation and recompaction.
Prediction of permeability of fissured tills
Authors: Hossain Delwar
Published: November 2007

Fissures of varying sizes, orientations and surface coatings present in Scottish lodgement tills influence their mass permeability and consolidation rates, inducing three-dimensional anisotropy in these properties. Satisfactory laboratory measurements require the costly testing of large specimens. This paper calculates the contribution of a discontinuous fissure to the flow through a fissured region by use of the finite element method and presents a method of prediction of mass permeability and its three-dimensional anisotropy by empirical computer-aided models based on the observed properties of the fissures and of the intact blocks. The results of such predictions have been found to compare satisfactorily with those from actual tests on relatively large undisturbed till samples of various orientations from three sites in West Central Scotland. Such a method is expected to reduce sampling and testing requirements for the above properties of fissured tills and possibly other similar soils.
Permeability of fracture zones in a Precambrian granite
Authors: Banks D. , Solbjørg M. L. , Rohr-Torp E.
Published: November 2007

Prior to the excavation of a 4 km subsea tunnel in the Precambrian Iddefjord Granite of southeast Norway, major fracture zones were located by use of aerial photographs and seismic techniques. When encountered during tunnel construction the majority were found to be of low transmissivity and to be filled with secondary clay minerals. Water inflows to the tunnel tended to occur through lesser, simpler fractures not detected by the preliminary investigations. This finding is supported by experiences from other tunnels and implies that the identification of major fracture zones by geophysical and remote sensing techniques may not always be a satisfactory method of locating groundwater resources in hard rock aquifers.
Tuen Mun New Town, Hong Kong
Authors: Hadley David
Published: November 2007

Tuen Mun is one of a series of large new towns being developed in Hong Kong's New Territories as part of the Government's strategy of decentralization from the highly congested urban areas of Kowloon and Hong Kong Island. It is located in and around Castle Peak Bay in the west of the Territory, about 30 km from Kowloon.

In order to obtain the necessary land to accommodate the town and much of its infrastructure, an extensive reclamation was required in Castle Peak Bay. Additional land was provided by raising fiat low-lying areas and by excavating large terraces into the surrounding mountains and hills. These operations have resulted in more than 1200 ha of new land being formed for the town. More than 30 million cubic metres of dredged and land-won material were used during the reclamation work.

The solid geology of the Tuen Mun area is dominated by Mesozoic volcanic and intrusive igneous rocks, mainly comprising andesitic lavas and tufts and fine-medium grained granites. The valley is also underlain in part by Palaeozoic sedimentary rocks. A mantle of weathered material typically overlies the bedrock in most of the area. Superficial deposits occur onshore and offshore and comprise alluvial and marine sequences together with debris flow deposits, which are common in valleys and also as large fans in downslope areas. Debris flow deposits can also occur offshore beneath the recent marine sediments.

Numerous land and marine ground investigations have been carried out throughout the development area over a number of years
A note on seepage from retaining wall weepholes
Authors: Au S. W. C. , Pang K. K.
Published: November 2007

This paper reports an investigation into the source of seepage from weepholes of a retaining wall. The findings explain the reasons for the lack of pattern commonly encountered in seepage from retaining wall weepholes. They also provide an insight into the mode of underground water flow in typical Hong Kong ground conditions.
Use of AASHTO classification to evaluate soils for road construction in Jamaica, West Indies
Authors: Maharaj Russell J.
Published: November 2007

The engineering properties of selected soil samples from Upper St Andrew, Jamaica and their suitability as sub-grades and sub-bases for road construction are presented. A few soil samples are potentially good for sub-bases (17 out of 42), namely the highly granular, non-plastic to low plasticity soils developed over highly fractured, slightly weathered igneous lithologies, coarse clastics or limestones. Clay-rich soils are unsuitable as sources of sub-grades. These were either bauxitic clays or clays within Alluvial Terrace and Alluvial Deposits, developed over mudrocks or highly altered igneous lithologies. Coarse granular soils with low plastic fines, developed over moderately weathered igneous lithologies or interbedded mudrocks and coarse clastics rated fair to poor as sub-grades but may be suitable if adequately drained and compacted and additional thicknesses of base courses added.
A suggested method for the classification of rock mass weathering by a ratings system
Authors: Price D. G.
Published: November 2007

The author expresses the doubts that many have with regard to the efficacy of the present methods of describing rock mass weathering. As an alternative to these methods the author recommends the use of a ratings system which classifies weathering in terms of engineering significance. The author also recognizes that all ratings systems which are successful have been developed over the years as a consequence of the experience of many users, but proposes, as a starting point for further discussion, a ratings system developed during engineering geological fieldwork in Spain.
Engineering geology of North Lantau, Hong Kong
Authors: Franks C. A. M. , Woods N. W.
Published: November 2007

Results of an engineering geology study of the northern part of Lantau Island in the west of Hong Kong are described. Over the next few years this area will be subject to major changes as a result of the planned new international airport at Chek Lap Kok. As a consequence of the airport, high-speed road and rail links are also planned along the coast of North Lantau, together with two new towns, industrial developments and a major port development at the eastern end. The study identified specific engineering geological problems and hazards with major safety or economic implications for the planned developments.

The western end of the island is mostly rugged mountainous terrain with elevations rising to more than 900 m above sea level. Towards the east, the topography is more subdued, although hillslopes are generally still steep.

The solid geology of the area is dominated by volcanic and intrusive igneous rocks of Mesozoic age, including volcanic tuffs and lava, granites and quartzphyric and feldsparphyric rhyolite dykes. These have weathered and a mantle of saprolite and residual soil covers much of the terrain. The onshore superficial soils include colluvium and alluvium whilst offshore, thick deposits of Holocene marine muds and Pleistocene alluvium overlie the weathered bedrock.

The main geological and geotechnical constraints to development on land in the North Lantau area are: the possible adverse effect of relict joints on the stability of cut slopes, potential stability problems on natural slopes due to steep, colluvium covered slopes, boulder fields and the possible remobilization of colluvium within drainage courses during rainstorms. Difficulties may also be encountered with piled foundations due to the presence of large boulders in deposits of alluvium and colluvium. Offshore, the presence of thick deposits of compressible marine mud represents the main difficulty for the planned reclamations along the coastline.
Geotechnical evaluation of untreated and cement-treated Ajali Sandstone from southeastern Nigeria
Authors: Eze E. O. , Suoware O. P.
Published: November 2007

The grain size analysis and the Atterberg limit values indicate that the Ajali Sandstone falls into the A-3 and SP-SW classes of the AASHTO and the Unified Soil Classification systems respectively. The low values of the coefficient of uniformity 2.9-3.4 show the deposit is uniformly graded and the soil is deficient in silt-clay fractions. At the optimum moisture content of 8% the untreated soil has a maximum dry density of 1.77 Mg/m3. The CBR of the soil when compacted to the standard Proctor optimum and soaked for three days is 10%. To establish the effective cement requirement of the soil, 5, 7, 9 and 110y weight of Portland cement was added to the soil. Results show that 80f the stabilizer meets the required minimum CBR of 100% and the 7-day uniaxial compressive strength of 1.4MPa (l.4 N/mm2). On ageing, the stabilized A-3 soil gains appreciably in strength.
Decay of building stones: a mineralogical model for Konark Sun Temple, India
Authors: Raymahashay B. C. , Sharma S.
Published: November 2007

The rapid decay of the famous sun temple at Konark is mainly due to the use of a highly weatherable khondalite rock as the construction material. A computer based weathering model indicates that the measured porosity of 7 to 8 0n weathered khondalite could have been produced if an original rock with 3 : 1 quartz to garnet weight ratio decayed to such an extent that 70 to 900f the garnet was altered. From the kaolinite and goethite generated as weathering products, the mole fractions retained would be 0.5 and 0.1 respectively.
A photographic method for rapid assessment of landslide displacement
Authors: Kalaugher P.G. , Grainger P.
Published: November 2007

During the summer months when the local demand for water is heavy the supply for Lyme Regis in Dorset, UK, relies on water pumped from a nearby spring at Pinhay in the lower levels of the area of landsliding known as the ‘undercliff’ (Pitts 1983). From cliffs that reach a height of 160 m AOD retrogressive slumping of the Chalk and Chert Beds has occurred mainly into the underlying Foxmould, which is a silty fine sand susceptible to liquefaction. These Cretaceous formations together constitute an aquifer that unconformably overlies the much less permeable mudstones and limestones of the Lower Lias. The debris from the degraded slumping of the Cretaceous strata has a high water table and forms a shallow apron of weak material which spills over the low cliff of Lias on to the foreshore.

The Earth Resources Centre of the University of Exeter has been monitoring, by a combination of surveying and photographic techniques, the displacements across the major scarps and the toe area of those landslides which directly affect the continued operation of the Pinhay pumping station (Grainger
et al.
1985, 1996; Grainger & Kalaugher 1995). Of particular concern are the displacements of the toe in the area immediately seaward (south) of the pumping station, which threaten eventually to undermine its foundations. From near the seaward edge of this toe area the view to the west along the beach and wave-cut platform includes a group of very large boulders derived from the Chert Beds. These boulders form a
Interpretation of field and laboratory shear strength data of a soft marine clay
Authors: Indraratna B.
Published: November 2007

Soft Muar Clay in Malaysia is of marine origin, and is characterized by a high water content that is close to or greater than its liquid limit. The variation of
in situ
vane shear strength is compared with various undrained laboratory tests conducted on undisturbed specimens recovered from different depths. The effects of the overburden pressure and Atterberg limits on the vane shear strength are discussed. Correlations between the field vane shear strength and the cone penetration resistance are also determined, and the effect of plasticity index on the normalized cone resistance is discussed. The results obtained for the Muar Clay are compared with other available data for selected soft marine clays. The use of the corrected and uncorrected vane strengths in the prediction of slip surface is also discussed.
Swelling characteristics of Madinah clays
Authors: Hossain Delwar , Matsah Mohammad Ibrahim , Sadaqah Bahaeldin
Published: November 2007

Six expansive clays from the city of Madinah, Saudi Arabia have been investigated. The expansive nature of these clays is due primarily to the presence of smectite. The basaltic lava around Madinah is considered to be the source of this mineral. Kaolinite and illite also present in these clays are thought to be derived by the alteration of smectite. Calcite occurs only in the ‘white clayey silt’ and in the ‘upper brown clay’. Qualitative estimates using plasticity index and clay fraction data suggest ‘low’ to ‘very high’ swell potentials of these clays. Laboratory swell-consolidation tests indicate that for initial liquidity index in the range of -0.91 to +0.32, the percent swell for these clays is 1.02% to 13.2% and the swell pressure range is from 58 kPa to 770 kPa, the higher values of these two parameters being observed for grey-green clays with liquid limit less than 120% and particularly at low moisture contents. The swelling characteristics of expansive clays depends on numerous factors making the prediction of volume change and swell pressure difficult. This paper discusses the use of multi-variate analysis to aid the prediction of these parameters for the Madinah grey-green clays. The progressive lowering of the groundwater table in the Madinah area is likely to promote more severe desiccation of Madinah clays in the future. In view of the high swell potential of Madinah clays, there are important implications in relation to foundation design in Madinah.
Pore size distribution and the durability of a porous limestone
Authors: Ordóñez S. , Fort R. , Garcia del Cura M. A.
Published: November 2007

A comparison of durability estimations based on mercury porosimeter data and experimental salt crystallization tests carried out on Bateig Stone from Alicante, Spain, establish that the main factor in the salt crystallization durability test is the ‘ink bottle’ pore system, identified by the presence of residual mercury in large pores after porosity testing. In addition, the results suggest that the commonly used indirect durability tests may not be considered a scientific definition of building stone behaviour.
Hydrogeochemistry of coal mine drainage and other ferruginous waters in north Derbyshire and south Yorkshire, UK
Authors: Banks David , Burke Sean P. , Gray Colin G.
Published: November 2007

Fifteen coal mine drainage waters from the Millstone Grit and Coal Measures of Derbyshire and Yorkshire have been compared hydrochemically with other iron-rich waters from spoil tips, natural springs and lead mine soughs in the area. The coal mine waters typically contained several tens of mg/l iron, with a range from 0.1 to 101 mg/l, and sulphate from 60 to over 1000 mg/l. The waters are undersaturated with respect to siderite. There is a strong linear correlation between iron and sulphate indicating that pyrite weathering is the dominant source of these parameters, although iron appears to be preferentially removed by precipitation or adsorption within the mines. The pH values of coal mine water are typically
c
. 6, although one water has a pH of 3.6, contains some 17 mg/l aluminium and lacks the saturation relative to gibbsite and kaolinite present in the other waters. The coal mine waters may be net acidic or net alkaline: there is some evidence to suggest that the former are typically derived from unsaturated, underdrained (i.e. drained from underneath the workings) shallow workings and the latter from saturated, overflowing workings.

The spoil tip waters are neutral to alkaline and saline. A possible explanation for this is the leaching of residual pore-water brines from the deep (several hundred metres) mined strata. The spoil tip leachates are poor in iron, which may be retained as iron hydroxides, sulphates or even siderite within the spoil.
Water from sand rivers in Botswana
Authors: Herbert R.
Published: November 2007

The term ‘sand river’ is used in Botswana for a particular type of ephemeral river channel similar to the ‘
wadi
’ of North Africa and elsewhere. Figure 1 shows a typically linear stretch of the sand river near Chadibe in Botswana. Up to 100 m across, sedimentological studies show sand rivers to be filled with a complex mixture of clays, silts and sands. The most recent deposits overlie the main water-bearing deposits and were laid down since the last major flood which has been dated as occurring about 100 years ago. At Borolong the river was 50 m wide, the most recent deposits were 0.5 m thick, the full depth was 3.5 m and the high yielding sands were 10 m from the crystalline embankment.

There is perennial groundwater flow in the sand rivers even though the riverbed is dry for most of the year. It has been estimated that a total of over 900 km of sand rivers in Botswana could supply as much as one third of the country's domestic water needs from the water stored in them.

Collector wells

One of the most efficient ways of extracting water from thin shallow aquifers is via collector wells. These are large diameter shafts from the base of which an array of horizontal holes extends into the aquifer. Figure 2 illustrates how a collector well works. Collector wells have been constructed by the BGS in several parts of the world in weathered rock and flood-plain deposits. Sand rivers present special drilling
Point load testing of weak rocks with particular reference to chalk
Authors: Bowden A. J. , Lamont-Black J. , Ullyott S.
Published: November 2007

The Point Load Test (PLT) was developed as an index test to predict the Uniaxial Compressive Strength (UCS) of core too broken for UCS testing. A correlation factor (
K
) between UCS and PLT strength of 24 has been proposed although this value is disputed. This paper investigates the value of
K
for chalk and other weak rocks using published and unpublished data sets and concludes that
K
is not a unique value even for a single set of specimens but is strength dependent, generally being between 10 and 20 for weaker rock (>25 MPa). It is often less than 10 for rocks of 5 MPa strength or less. Operator error is evaluated and considered to contribute to much of the reported scatter in Point Load Test results. The PLT is considered an appropriate and useful test for predicting the UCS of weak rocks provided that the ISRM methods are strictly observed and that samples with a range of strengths are tested to determine the variation in the correlation factor
K
with change in strength.
Influence of rainfall intensity and duration on slope stability in unsaturated soils
Authors: Ng C. W. W. , Shi Q.
Published: November 2007

Rain-induced landslides are major geotechnical hazards. The influence of infiltration under various rainfall, ground conditions on slope stability is still poorly understood. In this paper, a finite element parametric study was carried out to investigate the influence of different rainfall events and ground conditions on transient pore water distributions in unsaturated soils. A steep, unsaturated colluvium hillside in Hong Kong was chosen: the initial water table, rainfall intensity and rainfall duration were variables. Pore water pressures predicted during the transient seepage analyses were used as input groundwater conditions for subsequent limit equilibrium analyses of the stability of the slope. Shear strength variation due to the presence of matrix suction was also taken into account. It was found that the factor of safety not only depended on the intensity of rainfall and the initial groundwater table, but also on rainfall duration. A critical rainfall duration was identified, when the factor of safety was the lowest.
Discussion on ‘Reappraisal of time-dependent subsidence due to longwall coal mining’ by N. R. Goulty & S. Y. S. Al-Rawahy(Quarterly Journal of Engineering Geology, 29, 83–91)
Authors: Wilson E. J.
Published: November 2007

E. J. Wilson writes: Goulty & Al-Rawahy conclude
that, since different mechanical processes are involved in
active and residual subsidence, one should not attempt
to predict the duration of residual subsidence from
observations of active subsidence. Whilst this is obviously
true in a literal sense, the possibility that active
subsidence may result in delayed and possibly prolonged
residual subsidence should be considered.

The authors quote two cases by Orchard & Allen
(1975) in the Durham Coalfield where the presence of
thick competent strata prolonged residual subsidence to
six years (Peterlee) and delayed the onset of residual
subsidence by four years (North Durham). It is significant that both cases showed broadened subsidence profiles.
They go on to quote Pine & Randon (1986) who
recorded bedding separation below the thick Lower
Magnesian limestone in the Selby Coalfield, where active
subsidence at the Wistow Mine had produced less than
half the predicted settlement, and concluded that bridging
in the Permo-Trias can persist until the adjoining
panels are worked out. Reference is made to further
examples presented by Orchard & Allen (1975) and
Collins (1978). In one of the cases quoted by Collins at
Pengam, residual subsidence came to a stop after 2.5
years, and was noted by Collins to form a large proportion
of the active subsidence. In that case however
the active subsidence had only been about half of that
predicted. At Pengam, as also at Bedwas, prolonged
residual subsidence was ascribed to the presence of very
thick Pennant Sandstone in the
Spheroidal weathering of Deccan Basalt: a three-mineral model
Authors: Chatterjee A. , Raymahashay B. C.
Published: November 2007

Spheroidally weathered boulders occur in Deccan Basalt near Sagar, India. A simplified weathering model was developed to depict the alteration of the three primary minerals bytownite, augite and magnetite to an assemblage of beidellite, kaolinite and goethite. It was concluded that the thin concentric shells characteristic of the boulders resulted from an increase in volume during weathering. An iterative computer program showed that maximum expansion can be achieved through an appropriate combination of initial modal composition, fraction of each mineral altered and the relative proportions of beidellite, kaolinite and goethite in the weathered rock.
The micro-scale hydrogeological properties of the Lincolnshire Limestone, UK
Authors: Greswell R. , Yoshida K. , Tellam J. H. , Lloyd J. W.
Published: November 2007

As part of an integrated study of the ‘dual porosity’ hypothesis, a detailed micro-scale hydrogeological study was conducted of the rock material from a quarry excavated in the Lincolnshire Limestone. Permeability and porosity determinations allow comparisons to be made with the lithostratigraphy and show that the matrix hydraulic conductivities are inconsequential in terms of groundwater flow. The relatively high porosities typical of these limestones, combined with large surface areas associated with the major bedding plane fissures, provide a mechanism in which diffusive transport can become a significant factor in contaminant migration. The diffusion coefficients (
D
*) of three tracers used in field investigations (bromide,fluorescein and amino g acid) were measured in each of the main rock materials from the site using both double reservoir and reservoir depletion techniques. In addition, an assessment was made of
D
* estimation using an electrical resistivity method. Alteration of the matrix due to calcite dissolution of the fissure faces creates a zone of enhanced permeability and porosity. The presence of a fissure fill results in a ‘multiporosity’ interface between the fissure and the matrix that may significantly increase the mass of contaminant entering the pore fluid by diffusion in comparison with a simplistic conceptualization of this zone.
The glacial succession in lowland Northern England
Authors: Hughes D. B. , Clarke B. G. , Money M. S.
Published: November 2007

The landscape of Northern England has been subjected to glacial activity several times during the Quaternary period. Successive ice sheets may have ‘swept clear’ the bedrock surface in places, but may also have incorporated materials from previous glaciations into later formations, and eventually into the present cover of glacial till. Hence, almost all the till materials now existing over Northern England were deposited during the last major ice sheet glaciation, which is known as the Late Devensian or Dimlington Stadial. These glacial tills are engineering soils, and the variable and often complex successions in which they occur have frequently led to problems on civil and mining engineering projects. Many theories have been proposed to explain the complex distribution and succession for the Late Devensian tills, which have involved the waxing and waning of the ice sheets, variations in the directions of ice flows, and other changes in the glacial and post-glacial environments. This paper attempts to summarize the published research and compare this with the authors' own experience and observations gained mainly from opencast coal mining operations in the exposed lowland coalfield areas of Cumbria, Northumberland, Tyne & Wear and County Durham. Finally, the implications for ground investigations, plus the design of stable excavations and other earthworks, are briefly discussed in the light of this experience.
Intrinsic compression and swelling properties of a glacial till
Authors: Clarke B. G. , Chen C.-C. , Aflaki E.
Published: November 2007

The heterogeneous tills of Northrn England and Scotland are difficult to sample and test if using standard UK site investigation practice which was primarily developed for soft to stiff sedimented clays and sands. Application of empirical correlations and theoretical models to help select design parameters that were developed from standard tests on natural and reconstituted sands and clays may not be correct for tills because of their different mode of deposition and spatial variation in particle size and type. A geotechnical model is needed to explain the behaviour of tills which includes studies of the deposition and post-depositional processes, intrinsic properties of reconstituted till, and a database of results of natural till.

Results of one-dimensional and isotropic consolidation tests on reconstituted tills, reported here, have produced compression data that define the intrinsic compression line (ICL) and a band encompassing swelling lines over a pressure range of 6 kPa to 5 MPa. The intrinsic normal compression curves for the reconstituted tills agree with the ICL, therefore developments in the application of the ICL can be applied to tills. Furthermore, a unique band, defining the intrinsic swelling properties, has potential for a baseline for the interpretation of mechanical tests on natural till.
The Cilfynydd flow slide of December 1939
Authors: Bentley S. P. , Davies M. C. R. , Gallup M.
Published: November 2007

This paper describes an investigation of the 1939 flow slide in colliery spoil at Cilfynydd Common, South Wales. The investigation concentrated on the geomorphological features and other aspects that were to be destroyed by a proposed reclamation scheme. The overall aim of the work was to compile a database of factual information on ground and material conditions at the flow slide site. The work involved geomorphological mapping, a site investigation which involved 18 trail pits and a detailed programme of laboratory testing including fabric analyses. The results of the study indicated distinctly different fabrics for materials from different locations in the failed mass of the landslide. In triaxial stress path tests excess pore water pressures were generated very rapidly during shearing, indicating the susceptibility of slopes formed of colliery spoil to fail by flow slide.