bluuebunny/crossref_metadata_2025 huggingface dataset:
A potential systematic error in laboratory testing of very loose sands
Authors: Sladen J. A. , Handford G.
Published: June 2008

There is a potential error in the determination of specimen void ratio in triaxial tests on very loose sands. This error can be attributed to densification during final saturation. The result can be an error in the determination of the location of the steady state flow line in void ratio – stress space. Stress levels on the steady state flow line at a given void ratio may be in error by two orders of magnitude. If carried through to the analysis of susceptibility to liquefaction, this potential error could be extremely unconservative. Test results are presented that illustrate this potential source of error. A laboratory procedure is proposed that provides a simple calculation of final specimen void ratio and is potentially more accurate than presently used procedures. Key words: triaxial testing, sand, liquefaction, steady state.
Multiple-block plane shear slope failure
Authors: Stimpson B. , Barron K. , Kosar K.
Published: June 2008

Field examination of highwall slope failures occurring in some coal strip mines in Alberta in association with bentonite has led to the concept of a multiple-block plane shear failure mode in which a series of individual block failures regresses back into the slope for distances up to five times the slope height. These failures cause a rapid deterioration of the bench from which the dragline operates, reduce productivity, and necessitate bench maintenance to provide a safe, stable bench prior to the next pass of the dragline.A probabilistic limiting equilibrium analysis was developed to predict the positions of successive failure blocks and its predictions were compared with slope geometry and laboratory strength data from a producing coal strip mine in which a failure was active.Two slope failures reported in the literature (Folkestone Warren landslips and an Oxford Clay brick pit, both in England) were reanalysed using the multiple-block plane shear failure mode, and it is suggested that this mode of failure offers an alternative explanation for the slope kinematics observed.Finally, the most effective means of reducing the probability of failure or controlling the extent of slope failure retrogression is by dewatering. Key words: slopes, failure, coal mining, bentonite, clay bands, plane shear, case history, probabilistic analysis.
Settlement record of tower silos built on Champlain clays
Authors: Morin J. P. , Gervais R.
Published: June 2008

Research has been carried out at Université de Sherbrooke since 1975 on the behaviour of agricultural tower silos built in the St. Lawrence Lowlands in the Province of Quebec. The structures considered are built over soft sensitive Champlain Sea clays. The current foundation designs usually rely heavily on qualitative estimations of the performance of previously built silos. Settlement surveys are now available for a 10 year period for 19 silos out of an original group of 28. Sampling and laboratory testing have been carried out at 11 of these locations, while Nilcon vane shear testing has been performed at each site. Settlement and stability calculations have been made. It is thus possible to compare the observed and predicted behaviours of each silo over a substantial period of time. Foundation design recommendations are proposed as a result of these observations. It is shown that the factor of safety against failure can be used as an indicator of settlement behaviour. Key words: case history, settlement, sensitive clays, tower silos.
Subsurface fracture surveys using a borehole television camera and acoustic televiewer
Authors: Lau J. S. O. , Auger L. F. , Bisson J. G.
Published: June 2008

Borehole television survey and acoustic televiewer logging provide rapid, cost-effective, and accurate methods of surveying fractures and their characteristics within boreholes varying in diameter from 7.6 to 15.3 cm. In the television survey, a camera probe is used to inspect the borehole walls. Measurements of location, orientation, infilling width, and aperture of fractures are made on the television screen and recorded on computer data record sheets. All observations are recorded on video cassette tapes. With the acoustic televiewer, oriented images of fractures in the borehole walls are recorded on a strip–chart log and also on video cassette tapes. The images are displayed as if the walls were split vertically along magnetic north and spread out horizontally. Measurements of fracture characteristics are made on the strip–chart log, using a digitizing table and a microcomputer, and the data recorded on floppy diskettes. In both surveys, an inclined fracture is displayed as a sinusoidal curve, from which the apparent orientation of the fracture can be measured. Once the borehole orientation is known, the true orientation of the fracture can be computed from its apparent orientation. Computer analysis of the fracture data, provides a rapid assessment of fracture occurrence, fracture aperture, and statistically significant concentrations of fracture orientations. Key words: borehole, television survey, acoustic televiewer logging, fractures, distribution, orientation, aperture.
Probabilistic design of slopes
Authors: Li K. S. , Lumb P.
Published: June 2008

This paper discusses some improvements on the first-order second-moment (FOSM) probabilistic approach to slope design. The stability model by Morgenstern and Price is used for the formulation of the performance function, thus enabling the FOSM method to be applied to the probabilistic assessment of a general slip surface. A new solution scheme is also used herein for Morgenstern and Price's method. It does not require iterations for the calculation of the interslice forces and the derivatives of the performance function can be evaluated analytically. The reliability index βHL defined by Hasofer and Lind is used as an index of safety measure. It has the advantage of being "invariant," that is, its value does not depend on the format of the performance function, a property considered lacking in the conventional reliability index. Reference is also made to the probabilistic modelling of soil profiles. The importance of the correlation structure of soil properties is highlighted and its effect on the reliability index βHL is discussed. Key words: slope stability, safety factors, reliability index, probability of failure, general slip surface, rigorous stability model.
Work as a criterion for determining in situ and yield stresses in clays
Authors: Becker D. E. , Crooks J. H. A. , Been K , Jefferies M. G.
Published: June 2008

A method of interpreting conventional oedometer test data using work per unit volume as a criterion for determining both in situ effective and yield stresses in clay is presented. This technique was applied to the results of oedometer tests carried out on samples of natural clay deposits and on specimens consolidated anisotropically from a slurry to a known effective stress state. The work per unit volume – effective stress relationship, using arithmetic scales, can be approximated or fitted using linear relationships. The intersections of these fitted lines are demonstrated to provide accurate values for in situ current and yield (preconsolidation) stresses. The yield stress is defined as the intersection of the initial fitted line and the linear relationship observed at higher stresses. The current effective stress is indicated by the first significant divergence of the data from the initial fitted line. These relationships apply to both conventionally (horizontally) trimmed specimens and to vertically trimmed oedometer samples. It is hypothesized that the in situ effective and yield stresses (in both the vertical and horizontal directions) in a natural clay can be determined by the work per unit volume interpretation of oedometer tests carried out on horizontally and vertically trimmed specimens. Key words: in situ, stress, yield, oedometer, interpretation, clays, work, state, K0, preconsolidation pressure.
Les éperons drainants dans les talus en déblai–présentation d'abaques de dimensionnement sur critères hydrauliques et mécaniques
Authors: Aigle P. , Desnouvaux F. , Prost J. P.
Published: June 2008

The object of this article is to present design charts that facilitate the design of a series of parallel drainage spurs in association with a drainage ditch used in cut slopes. The hypotheses, the operating instructions, and the field of utilization are fully detailed.The two needed dimensions are the depth and spacing of the drainage spurs.The design charts are of two main types:–simple dimensioning charts: providing information on possible combinations of depth and spacing that give the quantitative effect wished by the designer, such as lowering the level of the water table or increasing the safety factor;–optimization charts: proposing an estimation of the solution that minimizes the depth of the spurs per linear metre of slope, and subsequently the volume of the draining material.This article results from theoretical and experimental research carried out over several years. We have been using a composite analog model that allows the simulation of free-surface three-dimensional flows. Key words: drainage, cut slopes, slope stability, drainage spur, analog model, three-dimensional.
Cone penetration test calibration for Erksak (Beaufort Sea) sand
Authors: Been K. , Lingnau B. E. , Crooks J. H. A. , Leach B.
Published: June 2008

Interpretation of the cone penetration test in sands is generally based on empirical calibrations from tests in large-diameter calibration chambers. Although interpretation of these calibration data for clean sands in terms of the state parameter is expected to be broadly applicable to other sands, material-specific correlations are desirable for many projects. This paper describes a series of calibration chamber tests carried out on a sand dredged from the Beaufort Sea for construction of artificial islands. This Erksak sand is a uniformly graded, subrounded medium-grained sand with a fines content of 3–6%. The testing chamber described is 1.4 m in diameter, and allows independent control of vertical, horizontal, and back pressures on the sand sample. Samples of the sand were prepared by moist compaction to preserve the fines content, and then back pressure saturated.The chamber test data are presented and confirm that the Erksak sand fits the general trends observed for other sands very well. A method is also described that allows the interpretation to be consistent, even in the event that nonuniform void ratios occur in the samples. Measurements of horizontal stress behind the cone tip, which is a new development in cone penetrometer testing, are also presented. Key words: cone penetrometer, sands, in situ tests, state, calibration chamber, horizontal stress measurement.
Analytical and model studies of reinforcement of a layer of granular fill on a soft clay subgrade
Authors: Love J. P. , Burd H. J. , Milligan G. W. E. , Houlsby G. T.
Published: June 2008

The effectiveness of geogrid reinforcement, placed at the base of a layer of granular fill on the surface of soft clay, has been studied by small-scale model tests in the laboratory. In the tests, monotonic loading was applied by a rigid footing, under plane strain conditions, to the surface of reinforced and unreinforced systems, using a range of fill thicknesses and subgrade strengths. Continuous measurements were made of footing load and footing displacement, and deformations of the subgrade and of the geogrid reinforcement were measured from photographs. From these measurements the different mechanisms of failure in the unreinforced and reinforced system were established. Performance of reinforced systems was found to be superior even at small deformations, owing to the significant change in the pattern of shear forces acting on the surface of the clay, brought about by the presence of the reinforcement. Membrane action of the reinforcement only became significant at large deformations.A finite element computer program has been specially formulated to allow inclusion of a thin reinforcing layer, and to handle correctly the large deformations and strains induced in the physical models. This formulation is able to reproduce satisfactorily the main features of behaviour observed in the models, and may now be used with some confidence to perform accurate predictions for full-scale structures. Key words: bearing capacity, clays, finite elements, foundations, geotextile, granular materials, model tests, reinforced soil, roads.
Shape of creep curves in frozen soils and polycrystalline ice
Authors: Fish Anatoly M.
Published: June 2008

A new method was developed for determining creep parameters, particularly the time to failure, from a single linear plot in which an individual creep curve forms a straight line for primary and tertiary creep. Secondary creep is considered to be a principal point on this line that predetermines the onset of failure. The times to failure can be predicted even when creep tests are not complete by extrapolating information obtained for primary creep. Based upon T. H. Jacka's test data, prediction of creep strain was evaluated using the constitutive equation of A. M. Fish for entire creep and compared with the modified Sinha equation of M. F. Ashby and P. Duval for attenuating creep as well as with models for primary and secondary creep. It is shown that the shape of the creep curves, and thus the creep parameters, varies with stress, temperature, and other factors. Hence, a family of creep curves cannot be described by a constitutive equation with a single set of creep parameters that do not take into account these variations without loss in the accuracy of the creep strain calculations. Key words: frozen soil, polycrystalline, ice, creep, failure, time to failure, attenuation, constitutive modelling.
Piezo-friction-cone penetrometer testing in soft clays
Authors: Konrad J.-M.
Published: June 2008

A comprehensive in situ testing program using a 50-kN electric piezo-friction-cone penetrometer was carried out at three different sites in soft marine clays. In these soils, the measured penetration resistance and friction are less than 4% of the full design capacity of the load cells. Although the strain gauges are temperature compensated, the importance of temperature effects in these soil conditions is demonstrated. The paper outlines a testing procedure to minimize the errors associated with zero shift in cone testing and to obtain meaningful data in weak soils with 50-kN penetrometers.Pore-water pressure measurements along the shaft are essential to evaluate the in situ test results in soft soils. Pore pressure distribution along the shaft is dependent on soil type, and measurements should be made at both ends of the friction sleeve for complete soil characterization.Friction along the shaft is not uniform and is negligible over an initial length of about 2 cone diameters in soft clays. Key words: soft clays, pore pressure, friction, tip resistance, in situ testing.
Limit equilibrium method with local factors of safety for slope stability
Authors: Srbulov Milutin M.
Published: June 2008

Current design practice often involves the consideration of slope stability when the strength parameters of the soil or the pore pressures vary considerably within a slope. In these cases it is evident that, because of departures from homogeneity, the soil mass may slip along a noncircular surface and local overstress will occur if the factor of safety lies below a value of about 1.8. Overstress also occurs when a slope contains materials that activate their shear resistances under significantly different stress – strain relationships. Therefore, the objective of this paper is to describe a new limit equilibrium approach suitable for the consideration of the heterogeneous slopes. A new definition of local factors of safety distribution, not only along a trial sliding surface but also at the interfaces of wedge-shaped slices, is introduced considering the soil strain properties. The main features of the comptutational procedure are outlined. One illustrative example dealing with the stability of a heterogeneous slope is included. Key words: limit equilibrium, slope stability, local factors of safety.
Landsliding caused by Pleistocene glacial lake ponding–an example from central British Columbia
Authors: Eyles N. , Clague John J.
Published: June 2008

Sections cut through the Quaternary sediment fill of the Fraser River valley in central British Columbia provide evidence for large-scale landsliding during Pleistocene time. Especially notable are thick, laterally extensive diamict beds, consisting mainly of Tertiary rock debris, that occur near the base of glaciolacustrine sequences. These beds were deposited by subaqueous debris flows during one or more periods of lake ponding when advancing Pleistocene glaciers blocked the ancestral Fraser River. The association of diamict beds and glaciolacustrine sediments deposited during periods of glacier advance may indicate a genetic link between slope failure and lake filling. These observations (1) demonstrate the adverse effects of high pore pressures on the stability of slopes underlain by poorly indurated Tertiary rocks and (2) extend the known history of landslides involving these rocks back into the Pleistocene. Key words: landslides, debris flows, Pleistocene, glacial lake.
Comparison of predicted and observed responses of pipeline to differential frost heave
Authors: Rajani B. , Morgenstern N.
Published: June 2008

This paper describes the application of a simplified Winkler model to simulate the observed time-dependent responses of a pipeline at Caen, France, subjected to differential frost heave. The numerical Winkler model developed for a semi-infinite beam embedded in a creeping medium was used to evaluate the response of the Caen pipeline. Despite its simplicity, the Winkler model is able to predict the overall response of deflections and stresses which compares satisfactorily with observed data. In a previous study, the same Winkler analysis was applied to small-scale model steel pipelines embedded in polycrystalline ice, and satisfactory comparisons between the predicted and observed responses were obtained. Consequently, the analyses presented in this paper serve to reconfirm that the Winkler model can also be applied to analyze large-diameter pipelines subjected to differential frost heave. Key words : chilled pipelines, creeping foundation, frozen soils, frost heave.
Estimation of hydraulic fracture pressure in clay
Authors: Andersen Knut H. , Rawlings Colin G. , Lunne Tom A. , By Trond H.
Published: June 2008

For offshore drilling, and in particular when drilling from fixed platforms in deep waters, the mud pressure will be high compared with the hydraulic fracture pressure (i.e., the formation strength) close to the sea floor. The first casing (the conductor) should therefore be installed to a depth where the formation strength is sufficient to prevent hydraulic fracturing of the soil. The consequences of hydraulic fracture could be mud flowing into the formation and loss of mud circulation. This slows down the drilling and, in cases where large quantities of mud flow into the formations beneath the platform, may even threaten the integrity of the foundation soils and create a safety problem. A conservative approach with too deep conductor setting depths will, on the other hand, lead to high unnecessary costs. This paper presents a new approach for calculating hydraulic fracture pressures. The new calculation approach considers two important factors that are generally not covered by theories found in the literature: nonlinearity of the stress–strain properties of the soil, and pore-pressure changes in the soil due to changes in total normal stress and shearing of the soil. The stress–strain properties and the shear-induced pore pressure are determined from laboratory tests. The proposed calculation approach has been verified against a series of laboratory model hydraulic fracture tests and in situ hydraulic fracture tests carried out at numerous offshore sites. The paper also presents a rational approach to establish the maximum allowable drilling mud pressure in clay formations and recommends partial safety coefficients that depend upon the consequences of hydraulic fracture and the quality of the soil data. Key words : hydraulic fracture, boreholes, clay, conductor setting depth, model tests, in situ tests, calculations.
The analysis of relaxed criteria for erosion-control filters
Authors: Adel H. Den , Koenders M.A. , Bakker K.J.
Published: June 2008

To optimize the design of erosion-control filters a transport model is presented for moving base material in horizontally loaded filters that are not geometrically stable. Supporting experimental work is used to obtain the parameters in a descriptive quantitative mathematical model. A set of three fixed parameters describes most experiments. Exceptions are where the filter to base grain-size ratio is so small that geometrical obstruction takes place and where this ratio is so large that the turbulences in the flow cause the sand surface under the filter to ripple. The latter case is described with a slightly amended parameter to allow for the amount of fluctuation in the problem. Key words : filtration, transport, experiments, theory, granular material, barriers.
Effect of pile driving on adjacent piles in clay
Authors: Poulos H.G.
Published: June 2008

When a pile is driven into clay, horizontal and vertical movements are developed in the soil surrounding the pile. These movements will tend to develop axial forces and bending moments in adjacent piles that have already been installed. Possible consequences for these piles are (i) structural damage or cracking (of concrete piles) arising from the induced bending moments, (ii) tensile failure of the piles due to the induced axial forces, and (iii) lifting-off of the pile tip from the bearing stratum due to the axial induced movements. This paper describes the results of a theoretical analysis of the bending moments and axial forces developed in a pile due to driving of an adjacent pile in clay. The analysis uses approximate distributions of horizontal and vertical soil movements caused by pile driving, developed from a "strain-path" analysis, together with inferences from model pile test data. An examination is made of various factors that may influence the induced bending moments and forces, including pile spacing, depth of penetration of the adjacent pile, and number of piles driven. For a number of published case histories comparisons are made between theoretical and measured axial and lateral pile movements. In general, satisfactory agreement is found. Key words : foundations, lateral movements, pile driving, settlement, soil displacement.
The hydrogeological and contaminant-transport properties of fractured Champlain Sea clay in Eastern Ontario. Part 1. Hydrogeological properties
Authors: O'Shaughnessy Vince , Garga Vinod K.
Published: June 2008

Hydrogeological and geochemical investigations were conducted on four fractured Champlain Sea clay deposits in Eastern Ontario. The results from water level monitoring, maximum seasonal variations, and hydraulic head profiles revealed a hydraulically active fractured zone existing at all four sites. The depth of this fractured zone varies from site to site, ranging from 3.2 to 6.0 m. Slug test analysis indicated that bulk hydraulic conductivity values in the upper fractured zone range from 1.8 × 10−8 to 2.0 × 10−5 m/s. In contrast, the measured hydraulic conductivity values from the deepest piezometers range from 8.2 × 10−10 to 1.4 × 10−9 m/s. The geochemical analysis indicated the presence of three hydrochemical facies: a shallow "active" facies, a deep "inactive" facies, and an intermediate "transition" facies. The presence of tritiated groundwater well below the groundwater table indicates that the upper fractured zone at all four sites is hydraulically active. Key words : fractures, Champlain Sea clay, in situ testing, hydrogeology, geochemistry, hydraulic conductivity.
The hydrogeological and contaminant-transport properties of fractured Champlain Sea clay in Eastern Ontario. Part 2. Contaminant transport
Authors: Garga Vinod K. , O'Shaughnessy Vince
Published: June 2008

Contaminant-migration characteristics of fractured Champlain Sea clay were evaluated through laboratory studies and parametric simulations. Two different laboratory diffusion experiments were performed on five unfractured Champlain Sea clay samples. One test involved the placement of a single salt solution (NaCl) in contact with a fully saturated undisturbed clay sample, thus allowing downward chemical migration throughout the sample by diffusion only. The second test involved the placement of deionized water in contact with the undisturbed saturated clay, thus allowing an upward chemical migration by diffusion only. At the termination of the test, the soil samples were sectioned to determine the pore-water and adsorbed concentrations as a function of depth. Diffusion coefficients and retardation factors were determined from plotted data.Simulated profiles were fitted to the field data by using one-dimensional analytical models that represented solute transport in both fractured and unfractured porous media. The fractured simulations using laboratory measured effective diffusion coefficients and retardation factors with advective parameters measured during field investigations provided the best fit. The effectiveness of fractured Champlain Sea clay to retard contaminants migration is significantly reduced when dealing with low- and non-reactive contaminants. Parametric analyses of four hypothetical cases indicate that landfill sites on these clays should be designed with an engineered liner and a leachate collection system. Key words : adsorption, diffusion, laboratory study, contaminant transport, fractured clay.
Overview of the liquefaction assessment and seismic stability of Duncan Dam: Specialty session, 46th Annual Canadian Geotechnical Conference Saskatoon, Saskatchewan, September 27–29, 1993
Authors: Imrie Alan S.
Published: June 2008

This overview introduces a series of six papers describing the approach taken in a recent dam safety study to evaluate the liquefaction potential and deformation behaviour for the current seismic setting of Duncan Dam. The dam was originally designed and built in the mid-1960s and is an embankment structure founded on a thick sequence of glacial sediments. The papers were initially presented by a team of B.C. Hydro and their consultants at a specialty session held at the 46th Annual Canadian Conference in Saskatoon in September 1993. The papers provide an excellent summary of the current state of practice in evaluating liquefaction and post-liquefaction behaviour. Key words : embankment, liquefaction, seismic, specialty session.
Ground freezing and sampling of foundation soils at Duncan Dam
Authors: Sego D.C. , Robertson P.K. , Sasitharan S. , Kllpatrick B.L. , Pillai V.S.
Published: June 2008

In situ ground freezing to obtain undisturbed samples of a loose sand beneath the Duncan Dam in British Columbia is described. This was the first known use of ground freezing to assist in obtaining samples at depth greater than 10 m in Canada. Once frozen, the sand was cored and brought to the surface using a Cold Regions Research and Engineering Laboratory core barrel, which is used extensively in permafrost regions. The design, installation, and performance of the liquid nitrogen freezing systems are described in detail. The drilling, sampling, and preparation of the frozen core for transport to the testing facility are also outlined. The quality of the core retrieved during the sampling was judged to be excellent, and good agreement was found between the void ratios measured using both the frozen core and high-quality gamma–gamma density logging techniques, which were performed adjacent to ground-freezing and sampling locations. Key words : ground freezing, cohesionless soils, undisturbed sampling.
Results and implications of seismic performance studies for Duncan Dam
Authors: Byrne P.M. , Imrie A.S. , Morgenstern N.R.
Published: June 2008

Screening-level studies indicated large zones of the foundation soil beneath Duncan Dam could be triggered to liquefy under the design earthquake, resulting in flow slides that could lead to breaching of the dam. In these studies, estimates of the key soil parameters were obtained from an indirect procedure using penetration tests and Seed's chart, which is based on field experience during past earthquakes together with empirical correction factors for high confining stress and static bias. This is state-of-the-practice procedure in North America and is used because of the difficulty in retrieving and testing undisturbed samples of sand. With the high confining stresses present at the site, the indirect approach gave very low values of the key liquefaction properties of the soil, and the use of such low values in analyses indicated that major and costly remedial measures were required. Thus a more direct approach was undertaken. This involved both direct and semidirect determination of the key soil parameters through an extensive laboratory study based on testing of undisturbed samples obtained by freezing in situ. The results showed that both the triggering resistance and the residual strength values of the soil were very much higher than those obtained from the indirect approach. Analyses carried out using direct measurement of the key soil parameters indicated that the dam, in fact, would be stable. Key words : embankment dam, foundation liquefaction, sand, seismic performance, triggering resistance, undisturbed sample.
Excess pore pressure in a poroelastic seabed saturated with a compressible fluid
Authors: Yue Z.Q. , Selvadurai A.P.S. , Law K.T.
Published: June 2008

This paper presents an analytical investigation on the excess pore-fluid pressure in a finite seabed layer by taking into account the influence of a compressible pore fluid. The seabed layer is modeled as a poroelastic layer saturated with a compressible pore fluid and resting on a rough, rigid impermeable base. The surface of the poroelastic seabed layer is either completely pervious or completely impervious, and subjected to a normal surface traction induced by offshore structures. The paper presents analytical and numerical results to illustrate the time-dependent behaviour of excess pore pressure in the poroelastic seabed. The results demonstrate that the presence of a compressible pore fluid reduces the generation of excess pore pressure in the poroelastic seabed layer. Key words : excess pore pressure, poroelastic seabed layer, soil consolidation, compressible pore fluid, integral transforms.
Experimental verification of the theory of consolidation for unsaturated soils
Authors: Rahardjo Harianto , Fredlund Delwyn G.
Published: June 2008

An experimental program was designed to study the behavior of unsaturated soils during undrained loading and consolidation. A Ko cylinder was designed and built for the testing program. Simultaneous measurements of pore-air and pore-water pressures could be made throughout a soil specimen using this Ko cylinder. Four types of tests were performed on a silty sand. These are (1) undrained loading tests where both the air and water are not allowed to drain, (2) constant water content tests where only the water phase is not allowed to drain, (3) consolidation tests where both the air and water phases are allowed to drain, and (4) increasing matric suction tests. Undrained loading tests or constant water content loading tests were conducted for measuring the pore pressure parameters for the unsaturated soil. Drained tests consisting of either consolidation tests or increasing matric suction tests were conducted to study the pore pressure distribution and volume change behavior throughout an unsaturated soil during a transient process. The experimental pore pressure parameters obtained from the undrained loadings and constant water content leadings agreed reasonably well with theory. The pore-air pressure was found to dissipate instantaneously when the air phase is continuous. The pore-water pressure dissipation during the consolidation test was found to be faster than the pore-water pressure decrease during the increasing matric suction test. The differing rates of dissipation were attributed to the different coefficients of water volume change for each of the tests. The water volume changes during the consolidation test were considerably smaller than the water volume changes during the increasing matric suction tests for the same increment of pressure change. Key words : consolidation, Ko loading, matric suction, pore-air pressures, pore-water pressures, unsaturated soils
Modelling the effect of vertical drains in two-dimensional finite element analyses of embankments on soft ground
Authors: Hird C.C. , Pyrah I.C. , Russell D. , Cinicioglu F.
Published: June 2008

A recently developed method for modelling the effect of vertical drains in plane strain finite element analyses of consolidation beneath embankments on soft ground is applied to three case histories. Analyses are reported for the consolidation of the soil served by a single drain (a unit cell) under conditions of no lateral strain. In all three cases a good match was obtained between the average degrees of consolidation in an axisymmetric unit cell and the equivalent plane strain unit cell. This suggests that the method could be used to facilitate full two-dimensional analyses of many embankments. The results of the analyses are also compared with the available field data. Key words : vertical drains, consolidation, finite elements, embankments.
Design of reinforcing piles to increase slope stability
Authors: Poulos Harry G.
Published: June 2008

This paper describes an approach for the design of piles to reinforce slopes, involving three main steps: (1) evaluating the shear force needed to increase the safety factor to the desired value; (2) evaluating the maximum shear force that each pile can provide to resist sliding of the potentially unstable portion of the slope; and (3) selection of the type and number of piles, and the most suitable location of these piles within the slope. For step 1, stability analyses can be used to assess the required additional shear force for stability. Step 2 involves the use of a computer analysis for the response of a pile to laterally moving soil. This analysis can be implemented via a computer program ERCAP, and enables the resisting shear force developed by the piles to be evaluated as a function of pile diameter and flexibility and the relative depth of the soil movement in relation to the pile length. Step (3) involves the use of engineering judgement in conjunction with the analysis results from steps 1 and 2. The paper describes the ERCAP analysis and the characteristics of pile behaviour it reveals. The application of the approach to a highway bypass problem in Newcastle, Australia, is described in detail. In the final design, a total of 64 bored piles 1.2 m in diameter were used over a total length of slope cutting of about 250 m. The pile lengths ranged between 6 and 12 m, with the spacings varying between 3.2 and 6.0 m. Key words : analysis, boundary element, piles, soil–pile interaction, slope stabilization, soil mechanics.
An effective stress model for creep of clay
Authors: Morsy Mohammed M. , Chan D.H. , Morgenstern N.R.
Published: June 2008

An effective stress constitutive model to study the problem numerically of creep in the field is presented. A double-yield surface model for the stress–strain–time behaviour of wet clay is described. The model adopts the concept of separating the total deformation into immediate and delayed components. The yield surfaces employed are the modified Cam-clay ellipsoid and the Von Mises cylinder inscribed in the ellipsoid. The proposed numerical scheme incorporates the pore pressure based on field observations into a finite element analysis. An interpolation technique is used to determine the pore pressure at every element. A field example is presented to illustrate the interpolation technique procedure. The scheme not only avoids the complexity of making predictions of pore-water pressure, but also allows the analysis to be carried out in terms of effective stresses based on the actual observed pore pressure. Two stress integration algorithms based on the implicit calculation of plastic strain are implemented and tested for the double-yield surface model. A numerical simulation of stress-controlled drained creep tests confirms the numerical procedure. Key words : constitutive equations, creep, finite element, stress integration algorithms, effective stress approach, pore-water pressure.
Predicting creep settlements of foundations in permafrost from the results of cone penetration tests
Authors: Ladanyi Branko , Lunne Tom , Vergobbi Pierre , Lhuillier Bernard
Published: June 2008

As a joint research project sponsored by the French–Norwegian Foundation for Scientific and Industrial Research, the Norwegian Geotechnical Institute, Geodia/Geocean, and École Polytechnique have carried out in the summer of 1990 a series of special in situ pressuremeter and cone penetration tests at a permafrost site in Longyearbyen, Svalbard. The purpose of the testing program was to compare the results of the two different field testing methods and to check the potential of such methods for serving as a basis for prediction of the behaviour of foundations in permafrost. As pressuremeter test results have been presented in a previous publication, this paper shows only the results of cone penetration tests and their interpretation in terms of strength and creep parameters of the frozen soil. Subsequently, the same data are used to predict the behaviour under long-term axial load of two prefabricated and one cast-in-place concrete pile that were tested by the Selmer Furuholmen Anlegg A.S. in cooperation with the Norwegian Geotechnical Institute at the same site for 3 years. Key words : permafrost, cone penetration tests, piles field loading tests, creep settlement.
Shear wave velocity to evaluate in situ state of cohesionless soils
Authors: Cunning J.C. , Robertson P.K. , Sego D.C.
Published: June 2008

Shear wave velocity (Vs) measurements were carried out in a triaxial testing program on three different cohesionless soils. The Vswas measured using bender elements during consolidation and at ultimate steady state. After consolidation the soil samples were loaded in shear under constant strain rate triaxial compression either drained or undrained to determine their ultimate steady or critical state (USS) at large strains. The Vsmeasurements were used to develop relationships between the void ratio (e), mean normal effective stress (p′), and Vs. The shear loading results were expressed within the framework of critical state soil mechanics. The results of the Vsand USS information were combined with the state parameter concept to develop an equation to use field measured Vsto estimate the in situ consolidation state within a soil. Thus, the contractive–dilative boundary with respect to vertical effective stress for large strain loading can be determined from in situ measurements of Vs. These can then be used as a design aid to determine if a soil deposit is potentially susceptible to flow liquefaction. Worked examples to illustrate the procedure are given. Key words : shear wave velocity, cohesionless soil, in situ state, state parameter, liquefaction, laboratory testing.
Estimating the undrained strength of sand: a theoretical framework
Authors: Fear Catherine E. , Robertson Peter K.
Published: June 2008

A framework for estimating the ultimate undrained steady state shear strength of sand (Su) from in situ tests, which combines the theory of critical state soil mechanics with shear wave velocity measurements, is presented. For a particular direction of undrained loading, samples of a given sand at a constant void ratio will reach the same Su, despite the magnitude of the initial effective confining stresses. Unique Su/p′ or [Formula: see text] ratios for a given direction of loading exist for a particular sand only if state parameter is constant throughout the deposit. Normalized shear wave velocity, Vs1, can be correlated with void ratio and is therefore used to estimate Su for a given initial state and direction of loading. Strengths in triaxial compression are examined in this paper; however, the same framework can be used to estimate strengths under other directions of loading. The Su–Vs1 relationship is shown to be relatively sensitive and should be used more as a screening tool rather than an accurate means of predicting Su. Vs1 is converted to equivalent values of SPT (N1)60 and CPT qc1, and the results are compared with the current methods of estimating Su. Key words : in situ testing, liquefaction, sand, undrained strength.
The high pore pressures within embankment dams: an unsaturated soil approach
Authors: St-Arnaud Guy
Published: June 2008

Pore pressures substantially higher than expected are frequently measured within the cores of large dams. Typical observations are presented, and various hypotheses proposed to explain this phenomenon are summarized and briefly discussed. The hypothesis suggested herein is that the pore pressures are influenced by the free gases trapped during the submergence. These gases are compressed at the ambient pore pressure, which is decreasing in the flow direction. The degree of saturation and, therefore, the permeability decrease in the same direction. The pore pressures are thus higher than predicted in a uniform permeability condition. Free gases are dissolved in the water due to the increase of the pore pressures. They are carried in the seepage flow and come out of solution in the core or finally in the downstream filter after some decrease of the pore-water pressures. The increase of pore pressure with respect to the steady-state conditions is a function of many factors and is necessarily transient. Key words : pore pressure, embankment dam, unsaturated soil, permeability, seepage.
Standard penetration tests and pile behaviour under lateral goads in cohesioniess soils
Authors: Meyerhof G.G.
Published: June 2008

Previous analyses of the ultimate resistance and displacements of flexible piles under lateral loads in cohesioniess soils have been reevaluated by using simple correlations based on standard penetration tests. Reasonable agreement is found between observed and predicted behaviour, and the new estimates are similar to those from the previous more elaborate methods. Key words : cohesioniess soils, displacements, lateral loads, soil resistance, standard penetration tests.
Analyse des performances do profigomètre
Authors: Garneau Christian , Tanguay Marc G.
Published: June 2008

Amongst the equipment included in instrumentation programs for the construction of embankments on compressible soils, the full profile gage makes it possible to determine the profile of the vertical settlement by measuring the hydrostatic pressure in a flexible pipe filled with liquid and placed horizontally under a structure. Four full profile gages were installed under OLGA-C, which is a test fill built by Hydro-Québec near Matagami. On the site of OLGA-C, settlement tubes, located near the full profiles gages, have provided data that could be closely compared with those given by the full profile gages. Equipped with high accuracy pressure transducers (±0.1%), the full profile gages have shown settlement values within 1 cm, on the average, of the values obtained with vertical tubes. Key words : full profile gage, instrumentation, geotechnic, settlement data, fill construction, test fill. [Journal translation]
A MODIFIED JOINT INVENTORY POLICY FOR VMI SYSTEMS
Authors: GOU QINGLONG , LIANG LIANG , XU CHUANYONG , ZHA YONG
Published: June 2008

Vendor managed inventory (VMI) is a supply-chain initiative in which the vendor is authorized to manage inventories of agreed upon stock-keeping-units at retail locations. In this paper, a modified joint inventory policy is introduced for VMI systems where the vendor takes a standard (s, S) policy and the retailers utilize can-order policies.

Under the regime of a can-order policy, each retailer's inventory is controlled by three variables s, c and S. Once the inventory position of retailer k reaches its must-order level s(k), a dispatch from the vendor to retailers is triggered. At the same time, any retailer j, with inventory position at or below its can-order level c(j), is included in the dispatch and thus an economical consolidated dispatch quantity accumulates.

To formulate the policy, a renewal theoretic model for the case of Poisson demands is developed. Due to the complexity of the problem, it is difficult to get the analytical solution and thus simulations are utilized to obtain an approximate optimal decision. Finally, the results from simulations show that about 5 to 20 percent of the cost can be saved from utilizing of the modified joint policy, comparing with the standard joint (s, S) policy where both the vendor and retailers take (s, S) policies.
SURF — STRUCTURAL UNDUPLICATED REACH AND FREQUENCY: LATENT CLASS TURF AND SHAPLEY VALUE ANALYSES
Authors: LIPOVETSKY STAN
Published: June 2008

Lazarsfeld's Latent Structure Analysis (LSA) is applied to problems in marketing involving the choice of products with maximum customer coverage. The LSA is combined with Total Unduplicated Reach and Frequency (TURF) technique, and also with a tool from cooperative game theory, the Shapley Value (SV), also known as the fuzzy Choquet integral. SV is used for ordering the items by their strength in covering the maximum number of consumers, which provides more stable results than TURF. Structural Unduplicated Reach and Frequency (SURF) analysis is introduced as the LSA segmentation of customers with different preferences across the products. The blending of LSA with TURF and SV yields new abilities of the latent structured TURF and SV. The marketing strategy based on using these techniques permits the identification of the preferred combinations in media or product mix for different population segments.
PROFITABILITY ANALYSIS OF FREE UPGRADE POLICY
Authors: ZHU JISHAN
Published: June 2008

We consider a firm selling two similar products with different prices. When the lower-priced product is out of stock, the firm supplies the customer a higher-priced product with the lower-priced product price. The policy is called free upgrade. In this paper, we study the profitability of such policy. We formulate the problem as a two-product newsvendor problem, and prove that the firm achieves more profit with the free upgrade policy. We propose a simulation algorithm to find the solution and demonstrate our findings with some numerical examples.
RANKING DECISION ALTERNATIVES BY INTEGRATED DEA, AHP AND GOWER PLOT TECHNIQUES
Authors: LI HAN-LIN , MA LI-CHING
Published: June 2008

Data Envelop Analysis (DEA) and Analytic Hierarchy Process (AHP) are widely used methods in ranking decision alternatives. However, current DEA models are difficult to discriminate decision-making units through articulating the decision makers' preferences. While AHP and Gower plot models have to specify complete pairwise preferences without providing assisting information. This study develops an iterative method of ranking decision alternatives by integrating DEA, AHP and Gower plot techniques. The developed method first utilizes a modified DEA model to narrow the ranges of a decision maker's preferences. Then, the tentative ranks of the decision alternatives, computed by embedding the decision maker's preferences, are depicted via Gower plots to illustrate the cardinal and ordinal inconsistencies of these preferences. The decision maker then adjusts the preferences iteratively until the inconsistencies are within the tolerance.