bluuebunny/crossref_metadata_2025 huggingface dataset:
Heave and Settlement of Two Tall Building Foundations in Edmonton, Alberta
Authors: DeJong J. , Morgenstern Norbert R.
Published: April 2011

It is not often that there is an opportunity to obtain a detailed and overlapping record of ground displacements; that is, heave during excavation and settlement during and subsequent to building construction. This paper presents such a case record and describes briefly site stratigraphy, the instrumentation used, the data obtained, and its analysis. The structures in question are the 34 storey Alberta Government Telephones building and the adjacent 28 storey Oxford building, together comprising the A.G.T./Oxford Complex, located in downtown Edmonton.Heave points were embedded below the base of the 300 × 300 × 45 ft (91 × 91 × 13.7 m) deep A.G.T. excavation in over-consolidated soil. Their elevations were read several times during the phased 1-year excavation period, each time accompanied by measurement of the excavation dimensions. To January, 1972 2.5 years of settlement have been recorded from readings taken on more than 100 basement column plugs. In addition, visual observations were made, construction loading and piezometric data were obtained and laboratory soil tests were undertaken. Analysis of the data was initiated in an effort to gain a better understanding of the mechanisms governing the response of these over-consolidated soils to both loading and unloading.Heave response within the excavation area was found to be rapid and computable by elastic theory. Much of the heave occurred during excavation. The time dependent portion virtually ceased 2–3 months subsequent to cessation of excavation. The amount occurring at adjacent structures outside the excavation was less than that predicted from elastic theory. Analysis of settlement data indicates that during construction settlements are rapid at footing pressures less than the original overburden pressure and can be predicted using elastic theory. Subsequent settlement at higher footing contact pressures also occurs rapidly, but with a stress dependent modulus of deformation. In general, the moduli derived from laboratory test specimens were found to be unsuitable and unreliable. Several conclusions of importance to construction practice and foundation design are drawn relative to proximity effects and phasing of excavation and building construction.
Reticulate Ice Veins in Permafrost, Northern Canada
Authors: Mackay J. Ross
Published: April 2011

A reticulate ice vein network is of common occurrence in many lake and marine clays, glacial tills, and mudflow deposits in permafrost areas of northern Canada. The ice vein network may grade downward into high ice content soils at depth. Field observations suggest that the reticulate ice veins grew in vertical and horizontal shrinkage cracks, with much of the water being derived from the adjacent clay, in a semiclosed freezing system, rather than from an upward migration of water in an open system. The three-dimensional geometry of the ice vein network is a factor to be considered in drill hole sampling, thaw–consolidation studies, and differential settlement estimates.
Homogeneous triaxial tests on sand—criterion for homogeneity and measurement of volume changes
Authors: Raju V. S. , Deman F.
Published: April 2011

In triaxial tests with lubricated enlarged end platens on sand, the internal displacements have been measured using lead shots and x-ray technique. The strain distribution so obtained confirms the homogeneity of deformations. A comparison of the axial strain distribution over the height of the sample obtained with x-ray technique and from surface measurements using a precision theodolite revealed that the much simpler method of surface measurements can be used as a criterion for homogeneity of deformations.In addition a comparison of the volume changes measured using the more accurate x-ray technique and the simpler girth-gauges showed that even the most carefully made girth gauges will underestimate the volume increase and as such are to be used with caution.
Water flow induced by soil freezing
Authors: Arvidson Wayne D. , Morgenstern Norbert R.
Published: April 2011

A study to observe the effects of overburden pressure and other parameters on the freezing behavior of a saturated soil was undertaken. A linear relationship between effective overburden pressure and the flow of water into or out of a freezing soil was observed. The effective pressure at which no flow occurred was termed the shutoff pressure. At pressures less than the shutoff pressure water was sucked to the freezing front resulting in segregated ice, ice lensing, and heaving. This heaving could significantly exceed the heave due to the volumetric expansion of the in situ porewater. At pressures greater than the shutoff pressure water was expelled from the freezing front thereby reducing the volume of in situ water and resulting in a relatively small amount of heave. Shutoff pressure was observed to depend on soil type, stress history, and freezing temperature. The effects of overburden pressure upon flow of water in a freezing soil and frost heave were recommended as additional criteria for assessing soil frost susceptibility.
The stability of stage-constructed embankments on soft clays
Authors: Tavenas F. , Blanchet R. , Garneau R. , Leroueil S.
Published: April 2011

The stage construction of seven high embankments on soft clays on the north shore of the St. Lawrence Valley has provided an excellent opportunity to check the applicability of the concepts of limit and critical states to the analysis of the behaviour of clay foundations.The construction pore pressures have confirmed the development of a significant consolidation in the initial period of construction.The consequences of this consolidation on the behaviour of the clay, in particular in terms of available strength, and on the method of stability analysis have been found entirely consistent with the general model proposed by Leroueil, Tavenas, Mieussens and Peignaud.It is suggested that the so-called [Formula: see text] analysis based on the vane shear strength corrected according to Bjerrum gives the minimum factor of safety and may be too conservative during stage construction. Effective stress analyses are shown to be more representative of the true stability conditions, and they have been successfully used to accelerate the construction of the embankments.
Geotechnical problems encountered in moving the church at Most
Authors: Skopek J.
Published: April 2011

The present paper describes the transfer of a Gothic church in the town of Most from a site where exploitation of brown coal in an openpit mine is envisaged. In moving the building, the structure 30 m × 60 m in plan, weighing 10 000 t, was loaded on 53 transport cars and transported on a curved track for a distance of 842 m. On a 200 m long sector of the track the cars had to pass over an old openpit mine up to 34 m deep refilled with a heterogeneous fill. In order to avoid excess settlement during the moving of the church, a surcharge fill was constructed beforehand at this location. As a result of the surcharge load the original ground surface settled up to 99 cm in 17 months. After removal of the surcharge fill, the original ground level heaved up to 10 cm. During the moving of the church, settlement reached 5–7 cm. The method of transport is described as well as the transport equipment used, the underpinning of the church at the original site, and its foundation in the new position.
River erosion and bank stabilization — North Saskatchewan River, Edmonton, Alberta
Authors: Thomson S. , Townsend D. L.
Published: April 2011

The postglacial geology of the North Saskatchewan River valley in Edmonton is reviewed. Using radiocarbon dating by others, limited land survey, and aerial photography measurement, it is inferred that the river valley was quickly formed after glaciation during a period of rapid downcutting. Over the last 8000 years, the rate of vertical downcutting has been about 25 times slower than it was during the initial 5000 years following deglaciation. As the river reached its base level, lateral river migration occurred and erosion against the low-lying river terraces has been substantial. It is inferred that over the past century the lateral migration is probably at the rate of at least 30 m/century.Low-level erosion protection berms are required to stabilize the toe of a variety of landslides; however, they do not completely eliminate the causes of upper slope movement. The engineering considerations underlying the construction of four protective works are discussed and overall costs are presented.
Geotechnical considerations in the treatment of the foundations of the left abutment of King Talal Dam
Authors: Masannat Yousef M.
Published: April 2011

Geotechnical investigations revealed the presence of high hydraulic conductivity zones with high grout takes in the left abutment of King Talal Dam. Control measures were needed to protect the foundations against the anticipated high leakage losses as well as against the probability of piping erosion, which may develop along the weakness and high hydraulic conductivity zones. The porosity, hydraulic conductivity, and groutability characteristics of the geological formations of the left abutment were investigated in detail. The data were analyzed and conclusions were made concerning the heterogeneity of the geotechnical properties of the different geological formations, the effectiveness of cement–bentonite grouting in improving the hydraulic conductivity and groutability characteristics of the foundation materials, and the measures taken to safeguard the foundations of the dam against the potential dangers of piping erosion.
Prediction of hydraulic properties of synthetic nonwoven fabrics used in geotechnical work
Authors: Masounave J. , Denis R. , Rollin A. L.
Published: April 2011

The filtration performance of nonwoven thick synthetic fabrics used in soil stabilization, erosion control, and earth reinforcement is predicted from a proposed analytical method. The morphological analysis of many fabrics has been utilized to identify internal structure parameters responsible for their hydraulic properties and to predict percentage retention of soil particles in the analysed fabrics. Experimental data indicated a relationship between the water permeability and the fiber density of a fabric. Furthermore, data are given to enable one to predict the percentage retention of particles from fiber density.
The prediction of settlements and heave in clays
Authors: Kodandaramaswamy K. , Rao S. Narasimha
Published: April 2011

A simple hyperbolic relationship is proposed to characterize displacements with time for structures founded in clayey soils. These considered displacements are due both to settlement and swelling. The relationship proposed has an added advantage in that the ultimate displacement has been brought within the mathematical formulations. The data published by several investigators for a number of field cases have been used to establish this. The agreement between the observed and predicted values of displacement is good. The findings of this investigation have a potential value in the application to field problems.
Relict joints in completely decomposed volcanics in Hong Kong
Authors: Koo Y. C.
Published: April 2011

In a major cutting in the completely decomposed volcanics in Hong Kong, closely spaced relict joints were found throughout the residual soil. The persistence of the exposed joint surfaces varies from several centimetres to more than 10 m. The joint surfaces, which are generally smooth and sometimes slickensided, are usually coated with a thin black-brown deposit. The origin of this deposit is believed to be the precipitation of iron-manganese decomposition products that have filled the joints in the parent rock during the course of weathering. Chemical analyses carried out on typical specimens have confirmed a high concentration of iron and manganese oxides. Results of laboratory shear strength testing show that the peak strength parameters along joint surfaces and of the intact material are: c′ = 0, [Formula: see text] and c′ = 6 kPa, [Formula: see text] respectively. Analyses of joint survey data indicate that relict joint orientations occur in systematic major sets and that joint spacings roughly follow a Poisson distribution.
Thermal expansion, diffusivity, and cracking of rock cores from Darlington, Ontario
Authors: Lo K. Y. , Wai R. S. C.
Published: April 2011

Measurements of the thermal diffusivity and expansion coefficient for rock cores of a limestone and granitic gneiss, recovered from a deep hole at Darlington Generating Station, Ontario were carried out. Results showed that the diffusivity decreases whereas the coefficient of expansion increases with temperature for both rock types. Thermal cracking occurs above a threshold temperature that is independent of the rate of heating as indicated by wave velocity measurements; this appears to be a result of thermal mismatch of the mineral constituents. These results are of direct relevance to the design of underground facilities in energy-related projects.
Elastic and pseudoviscous properties of coal under quasi-static and impact loadings
Authors: Klepaczko J. R. , Hsu T. R. , Bassim M. N.
Published: April 2011

An investigation of the elastic and viscoelastic properties of Nova Scotia coal was carried out over a wide range of strain rates (quasi-static to impact). High resolution stress–strain diagrams for the coal were obtained from compression tests for the lower and medium strain rates up to [Formula: see text] and with the split Hopkinson bar technique for the high strain rate region up to [Formula: see text].The elastic properties of the coal showed a moderate rate sensitivity at low and moderate strain rates.Above the strain rate [Formula: see text] both Young's modulus and the stress level of microcracking initiation σf0isplayed extreme rate sensitivity and was found to be a linear function of strain rate. The associated coefficient of viscosity perpendicular to the bedding plane was η* = 3.08 × 104 Pa∙s.The viscoelastic model so determined can be used to assess the elastic properties of coal at even higher strain rates, a situation that is similar to an explosive loading. Keywords: coal, strain rates, dynamic, viscoelastic properties.
Les échanges radiatifs et énergétiques et le bilan thermique du sol en Jamésie
Authors: Singh Bhawan , Taillefer Richard , Poitevin Jean
Published: April 2011

Detailed and regular measurements of the components of the radiation and energy balances and of the thermal and water regimes of the soil to a depth of 5 m were conducted from August 1979 to August 1980 in an open pine forest near lac Hélène, Baie James. The results deriving from these measurements indicate that temperature conditions and thus seasonal frost in the ground are explainable in terms of radiative and heat energy exchanges near the surface, of the physical properties of the soil, of snow accumulation, and of water concentrations and movements in the soil. Keywords: surface energy exchanges, ground temperature, seasonal frost penetration.
Research on geotextiles for heavy haul railways
Authors: Raymond G. P.
Published: April 2011

Research has been conducted over the last several years on the use of geotextiles for mainline heavy tonnage railroad tracks. A wide range of geotextiles was observed to provide improvements in many short-term applications. However, many of these improvements were not long lasting. For longevity of the application a much greater discrimination between geotextile types, geotextile weight, polymer types, and fiber denier was found to be desirable. Also found important was the necessity to match the geotextile properties with the soils engineering properties and to follow correct construction procedures.Drainage was found to be the most critical aspect for achieving long-term stability in the track structure. Excess moisture within the roadbed was found to reduce the subgrade strength and provide easy access for fine grain soils to foul the open ballast. Proper drainage techniques combined with geotextiles are given special consideration.Conclusions are drawn regarding the desirable attributes that should be specified in preparing quality requirements for geotextiles to be obtained under conditions of competitive tendering. Keywords: geotextiles, synthetic fabric, fabric, railroad, tracks, track support, rehabilitation, soil mechanics.
Bearing capacity of rigid piles under eccentric and inclined loads
Authors: Meyerhof G. G. , Sastry V. V. R. N.
Published: April 2011

The ultimate bearing capacity of instrumented vertical single rigid model piles in homogeneous loose sand and soft clay under vertical eccentric and central inclined loads has been investigated. The results of these load tests provide a more realistic lateral soil pressure distribution on the pile shaft and better theoretical estimates of pile capacity under pure moment and under horizontal load. For intermediate eccentricities and inclinations of the load, the bearing capacity can be obtained from simple interaction relationships between the axial load and moment capacities and between the axial and horizontal load capacities, respectively. The influence of lateral soil pressures due to installation of displacement piles in clay is examined in relation to the ultimate load of the pile. The analyses are compared with the results of model tests and some field case records. Key words: bearing capacity, clay, eccentric loading, horizontal load, instrumentation, model test, pile, sand.
Movement and stability analysis of the Beaver Creek landslide, Saskatchewan, Canada
Authors: Yoshida R. T. , Krahn J.
Published: April 2011

This paper presents a case history of a multiblock landslide where the blocks move at varying rates along a common horizontal slip surface which follows the contact between stratified drift and underlying till. Movement measurements indicate that the blocks towards the toe move at a higher rate than blocks towards the scarp. Stability analyses show that the entire slide mass can be analyzed as a single unit as opposed to considering each block separately. This finding is compared with the analysis of other multiblock slides. The friction angle mobilized along the horizontal slip surface falls within the range of residual values measured in the laboratory. Key words: landslides, stability, analysis, translational slides, residual strength.
The measurements of soil parameters relevant to tunnelling in clays
Authors: Ng Robert M. C. , Lo K. Y.
Published: April 2011

A comprehensive laboratory program was carried out on specimens trimmed from 152 mm diameter piston samples of a soft silty clay and a varved clay at a tunnel site in Thunder Bay. Results of conventional triaxial tests as well as special tests for the determination of anisotropic elastic parameters, simple shear tests, and stress path tests are presented.Results indicate that the unloading moduli are about twice the loading moduli, the Poisson's ratios in unloading are about three times those in loading, but the independent shear modulus is relatively unaffected. While the modulus is sensitive to mode of consolidation, drainage, and direction of stress path, the stress states at failure of all the different types of tests fall close to a single envelope for compression and extension. The choice of soil parameters for the analysis of deformation in tunnelling in soft clays is discussed. Key words: clay, tunnelling, stress path, deformation modulus, shear modulus, anisotropic elastic parameters, failure envelope.
Field measurements of soil thermal conductivity
Authors: Goodrich L. E.
Published: April 2011

Data representing the seasonal variation of thermal conductivity of the ground at depths within the seasonally active freezing/thawing zone are presented for a number of different soil conditions at four sites across Canada. An inexpensive probe apparatus suitable for routine field measurements is described.In all the cases examined, significant seasonal variations were confined to the first few decimetres. In addition to distinct seasonal differences associated with phase change, quite large changes occurred during the period when the soil was thawed in those cases where seasonal drying was possible. Below the seasonally active zone, thawed soil conductivities did not differ greatly among the three nonpermafrost sites in spite of soil composition ranging from marine clay to sandy silt. The data suggest that, even within a given soil layer, quite significant differences in thermal conductivity may be encountered in engineering structures such as embankments, presumably because of differences in drainage conditions. Key words: thermal conductivity, field measurements, phase relationships, drying, permafrost, clay, silt, peat.
The mechanical behavior of the Kettle Point oil shale
Authors: Dusseault Maurice B. , Loftsson Matthias , Russell David
Published: April 2011

Samples of eastern black shale (Kettle Point oil shales, Ontario) were subjected to extensive mineralogical and geomechanical tests. We prove that the mineralogy, as measured by the ratio of quartz to illite, controls strength and deformation properties, and the organic material plays no significant role. The reason is that increasing clay content dilutes the rigid quartz–quartz grain contacts that are responsible for the high strengths and stiff behavior. Tests of temperature effects on point load strength of another low organic content oil shale confirm that organic matter is not important to mechanical properties in matrix-supported shales. Key words: shale, mineralogy, Brazilian test, triaxial strength, organic content, slake durability, thermogravimetry.
Creep behaviour of undisturbed clay permafrost
Authors: Savigny K. W. , Morgenstern N. R.
Published: April 2011

An in situ analysis of naturally occurring creep has been carried out at the proposed Canadian Arctic Gas pipeline crossing of Great Bear River in the Northwest Territories. This is the last of four papers that describe the study. Creep properties of natural and reconstituted frozen soils are briefly reviewed. A laboratory programme to measure creep properties of undisturbed ice-rich glaciolacustrine clay samples from the Great Bear River site is described in detail. The results are analysed to determine empirical parameters for constitutive equations that describe the stress–strain–time behaviour of the material. Key words: Mackenzie Valley, pipelines, slopes, ice-rich, soils, permafrost, geotechnical, creep, laboratory.
Hydraulic fracturing experiment at the University of Regina Campus
Authors: McLennan J. D. , Hasegawa H. S. , Roegiers J -C , Jessop Alan M.
Published: April 2011

A hydraulic fracturing stress determination was carried out during May and June, 1979, in a water well intended for the Geothermal Feasibility Project on the campus of the University of Regina, Saskatchewan. Four intervals between depths of 2062 and 2215 m were fractured successfully, one in the Winnipeg Formation (2034–2083 m), two in the Deadwood Formation (2083–2209 m), and one under the Phanerozoic sequence near the top of the Precambrian basement (2209–2215 m).Over the depth range (2062–2215 m) covered by this hydrofracture experiment, the results and inferences are as follow. Downhole breakdown pressure ranges from 42 to 45 MPa, and downhole shut-in pressure from 35 to 42 MPa. The minimum horizontal stress component, σhmin, is taken as being equal to the corresponding shut-in pressure. The vertical stress component, σv, is assumed to be essentially equal to the overburden pressure and varies from 51 to 56 MPa. Whereas σv and σhmin apparently vary smoothly across the Deadwood Formation, the maximum horizontal component, σhmax, appears to undergo a discontinuity in the upper part of the Deadwood Formation, as σHMAX varies from 40 MPa in the Winnipeg Formation to 53 MPa in the upper part of the Precambrian basement. In so far as seismotectonics is concerned, the physical implications of these measurements are that normal faulting should prevail in the Winnipeg (and overlying) formations whereas strike-slip faulting could occur in the Precambrian basement; however, the latter inference has not been firmly established. Breakdown pressure is a useful guide (upper limit) for the potential geothermal demonstration project. Key words: hydraulic fracture, fracture mechanics, faulting, stresses, in situ, breakdown, shut-in pressure, seismotectonics.
Dredged slopes at Thompson open-pit
Authors: McRoberts E. C. , Prochera R.
Published: April 2011

The development of an open-pit mine at Thompson, Manitoba, required the excavation by dredge of 17.6 × 106 m3 of overburden. The overburden consisted primarily of normally consolidated glaciolacustrine soils found beneath Thompson Lake. The paper reviews the geological and geotechnical characteristics of the varved deposits and the basis for establishing the overburden slope configuration. Previous experience on similar dredging projects in Manitoba and northwestern Ontario is reviewed. Performance data collected during the excavation of the dredged slopes are presented. Key words: dredging, slope stability, open-pit mine, glaciolacustrine deposit, varved soil, piezometric response.
A technique for long-term storage of clay samples
Authors: Rochelle P. La , Leroueil S. , Tavenas F.
Published: April 2011

This note describes a technique for sealing and storing clay samples so as to prevent aging effects during long periods of storage. It also gives the results of a study carried out on samples stored from 3 to 8 years, which prove the efficiency of that technique; the liquid limits, the liquidity indices, and the pH values remained constant during these long periods of storage. Key words: sensitive clay, storing, sealing, aging.
Field pile load tests in saline permafrost. I. Test procedures and results
Authors: Biggar K. W. , Sego D. C.
Published: April 2011

A pile load test program carried out in Iqaluit, Northwest Territories, to provide design information for the Short Range Radar sites is described. The program consisted of testing 10 steel pipe piles with various surface modifications backfilled with clean sand and 4 Dywidag bars backfilled with Ciment Fondu™ grout. All tests were performed in saline permafrost. This paper describes the site conditions, installation procedures and pile uplift load testing procedures, and results of the pile load tests. The beneficial effect of modifications to the pile surface and backfill material is identified. The analysis and discussions of the results are presented in a companion paper. Key words : permafrost, saline, piles, load tests, field, in situ, capacity.
Kinematically and statically plausible calculations for sheet walls
Authors: Mortensen Knud
Published: April 2011

The state of failure for an anchored sheet wall has been considered. Statical plausibility is achieved by demanding that it must not be possible to indicate an unstable logarithmic spiral starting from a point on the wall passing to another point on the wall or on the surface. Kinematical plausibility is achieved by assuming that the unit earth pressure attains the maximum statically plausible value where the wall moves towards the soil and the minimum statically plausible value where it moves away from the soil. For practical design, a spread sheet program has been developed taking the following factors into account: exterior vertical, horizontal, and moment loads acting on the wall; partial surcharge on the soil surface; stratification in the soil; tension cracks in cohesive soil; water pressures on the wall; all three equations of equilibrium for the wall; inclination of the anchor; different partial factors of safety on actions and strengths involved. When the characteristic parameters are determined and the partial factors selected in accordance with Danish practice, the results appear to be in good agreement with the most relevant practical experience at hand. Key words : earth pressure, sheet walls, theory of plasticity, ultimate failure.
Preloading thick compressible subsoils: a case history
Authors: Ripley Charles F.
Published: April 2011

A case history of preloading and surcharging a more than 300 ft (1 ft = 0.3048 m) thick compressible subsoil is presented, with data on the settlement analysis, the fill design, other measures used for control of settlements, and the 24 year postconstruction performance. The essential factors for successful application of preloading to thick compressible subsoils are discussed. Key words : preloading, settlement analysis, construction control, settlement behaviour.
Behaviour of water-jet mined caverns in oil sand and shale
Authors: Wong Ron CK
Published: April 2011

Cavern of up to 10 m in diameter were mined in oil sand and shale formations at depths of 500 m in Cold Lake, Alberta. The cavens were subjected to high-pressure water jetting, pumping bitumensand slurry to the surface, cyclic water pressurization and depressurization, and gas exsolution. Roof and wall shapes were monitored by sonar logs. Numerical models are proposed to explain the roof and wall sloughing mechanisms in oil sand and shale.

Key words: oil sand, shale, cavern, water jetting, collapse mechanism.
Pile response due to unsupported excavation-induced lateral soil movement
Authors: Poulos H G , Chen L T
Published: April 2011

In this paper, a two-stage analysis involving the finite element method and the boundary element method is used to study pile response due to excavtion-induced lateral soil movements, focusing on unsupported excavations in clay layers. It is shown that the pile response in this case is different from that caused by excavations which are braced. Design charts for estimating pile bending moments and deflections are presented for free-head single piles, and these may be used in practice for assessing the behaviour of existing piles due to the excavation. However, proper account should be taken of the pile head condition, which has been found to have a major effect on the pile bending moment. The application of the charts is demonstrated via a study of a published case history. Comparisons are presented between measured pile behaviour and that predicted both from the chart solutions and the computer analyses, and reasonably good agreement is found between them.

Key words: analysis, boundary element, excavation, finite element, pile, soil, movement.
On the determination of the stress-strain curve of clay from the undrained plane-strain expansion of hollow cylinders: a long-forgotten method
Authors: Silvestri V
Published: April 2011

This paper presents the method to obtain the shear stress curve of clay from the undrained plane-strain expansion of hollow cylinder triaxial tests. No prior knowledge of the constitutive properties of the material is required. The theory also indicates that when the outer radius of the cylinder is very large compared with the inner radius, the equation used to interpret pressuremeter tests in clay is recovered.Key words: hollow cylinder, expansion tests, clays, plane strain, undrained condition, shear stress curve.
Identifying crack initiation and propagation thresholds in brittle rock
Authors: Eberhardt E , Stead D , Stimpson B , Read R S
Published: April 2011

Recent work at the Underground Research Laboratory of Atomic Energy of Canada Limited in Pinawa, Manitoba, has shown that high compressive stresses near the tunnel face significantly contribute to the loss of strength, and eventual failure of the rock, through stress-induced brittle fracturing. A program of laboratory testing has been undertaken to investigate the effects of brittle fracture on the progressive degradation of rock mass strength. The work carried out in this study involves a detailed analysis of the crack initiation and propagation thresholds, two key components in the brittle-fracture process. This paper describes new techniques developed to enhance existing strain gauge and acoustic emission methodologies with respect to the detection of these thresholds and their effects on the degradation of material strength.Key words: tunnel, rock failure, brittle fracture, crack initiation, crack propagation.
The Frank slide: a reexamination of the failure mechanism
Authors: Benko Boris , Stead Doug
Published: April 2011

The Frank slide, involving an estimated 30 million m3 of rock occurred in 1903 on the east face of Turtle Mountain, southwestern Alberta, Canada. It resulted in the loss of approximately 70 lives. Numerous authors have discussed the mechanism of the slide, with both limit equilibrium and elastic finite element analyses being conducted. This paper represents the first published account of the application of elasto-plastic finite difference and distinct element techniques to the Frank slide. It constitutes an attempt to improve our understanding of the ground deformation processes involved. The results of an extensive elasto-plastic modelling study illustrate that although the prime cause of the slide was the adverse geological structure, mining at the base of Turtle mountain could have acted as a final triggering mechanism. This appears to be in agreement with accounts published at the time of the disaster.Key words: landslides, numerical modelling.
Electroosmosis-enhanced preloading consolidation via vertical drains
Authors: Shang J Q
Published: April 2011

An analytical model of electroosmosis-enhanced preloading consolidation via vertical drains is developed for the design of the combined preloading and electroosmotic consolidation of clay soils. The excess pore pressure and average degree of consolidation are computed and examined for the effects of surcharge load, electric field intensity, treatment time, spatial configuration of electrodes, drainage path, and soil properties. The model is evaluated using the results of a well-known electroosmotic consolidation field test reported in the literature.Key words: consolidation, electroosmosis, surcharge preloading, vertical drains, soil improvement, soft clays.
Evaluation of active earth pressure by the generalized method of slices
Authors: Chen Zuyu , Li Songmei
Published: April 2011

The generalized method of slices, commonly used in slope stability analysis, can be extended to determine active earth pressures applied to various types of supports. The governing force and moment equlibrium equations are given. In a similar manner to slope stability analysis, the methods of optimization are used to define the critical slip surface that is associated with the maximum wall pressure. Examples show that the approaches give active earth pressures identical to the Rankine solution for gravity walls. For other types of support, such as anchored or strutted walls, the earth pressure is determined by assigning appropriate locations of the point of application on the wall. It has been found that applying the restrictions of physical admissibility is more vital in earth pressure problems than in slope stability assessments.Key words: earth pressure, limit equilibrium method, the method of slices, retaining walls.
A numerical solution of cavity expansion problem in sand based directly on experimental stress-strain curves
Authors: Ladanyi Branko , Foriero Adolfo
Published: April 2011

A numerical solution of a spherical and cylindrical cavity expansion problem in sand is presented herein. The underlying theory is unbiased in that it is based directly on experimentally determined stress-strain curves. The solution makes it possible to follow the continuous variation of strains, stresses, and volume changes produced by cavity expansion. It essentially uses the "strain path" approach to determine the state of stress around the cavity, taking into account large strains and the effect of spherical stress variation on the mobilized shear resistance and the associated volume strains. A limited comparison with experimental data shows a reasonable agreement between theory and measurements.Key words: cavities, expansion, sand, stress-strain curves, numerical solution.
The eleventh annual R.M. Hardy Keynote Address, 1997: Centrifugation in geoenvironmental practice and education
Authors: Mitchell R J
Published: April 2011

Geotechnical practitioners and educators may correctly regard the major contributions of centrifuge modelling as relatively substantive and expensive research enterprises. There are, however, many everyday applications of centrifugation that could be made available to both practitioners and educators at a modest cost. Centrifuge modelling and testing at relatively low gravitational levels are particularly relevant to geoenvironmental practice and education; the following applications are typical: (1) centrifuge modelling to produce realistic data on the movement and fate of contaminants in ground water for the validation or further development of numerical simulations; (2) centrifuge testing for the determination of geoenvironmental properties such as hydraulic conductivities and diffusion coefficients in fine-grained soils; (3) centrifuge model design using dimensional similitude for continued education and a better understanding of geoenvironmental concepts. Large commercial modelling centrifuges are beyond the budget of most soils laboratories but smaller dedicated centrifuges, with limited modelling capabilities, can be economically constructed for educational purposes and to produce independent design information that is cost competitive with bench testing.Key words: centrifugal modelling, geoenvironmental practice, education, laboratory centrifuges.
The effect of brine on the creep behaviour and dissolution chemistry of evaporites
Authors: Lee R , Souza E De
Published: April 2011

To evaluate operational problems in evaporite deposit utilization associated with brine, halite, sylvinite, and carnallitic ore were creep tested under unconfined conditions, both with and without added brine. Axial deformation and dissolution chemistry where observed throughout the tests. In both the sylvinite and carnallitic ore tests, selective dissolution of sylvite and carnallite minerals was associated with the precipitation of halite. The nature of this process was dependent on temperature and initial brine and ore composition. Generally, the presence of brine caused a decrease in the resistance to creep deformation. It is suggested that observed weakening in evaporites under dilatant conditions and in the presence of brine is due primarily to the enhancement of fracture mechanics processes through selective dissolution from stressed areas in the rock, such as fracture-process zones and asperities acting as barriers to slip. Correlation of results with a variety of practical environments, including brine inflow problems, waste salt backfilling practices, and underground storage facilities, was possible. Since there is always inherent brine in salt rock deposits, the results also add to the existing body of knowledge regarding advanced evaporite rock mechanics in general.Key words: evaporite, potash, salt, brine, creep, mining.
Instrumentation and monitoring of an engineered soil cover system for mine waste rock
Authors: O'Kane M , Wilson G W , Barbour S L
Published: April 2011

The ability of the soil cover system at the Equity Silver Mine to limit oxygen and water fluxes to underlying waste rock was evaluated using a detailed instrumentation program. Field instrumentation was installed to monitor temperature, gaseous oxygen, and gaseous carbon dioxide in the waste rock piles. Lysimeters were constructed at the base of the soil cover system to monitor infiltration across the soil cover. Sensors to measure matric suction, soil temperature, and water content were installed. An automated weather station was also installed to monitor climate conditions at the mine site. The field data indicates that the lower compacted layer maintained a high degree of saturation (i.e., 90% or higher) during 3 years of data collection (August 1992 to August 1995). This is a positive result, since the lower compacted layer was designed as an oxygen limiting barrier. The average measured infiltration from lysimeters placed at the base of the soil cover system was 5% of precipitation (from October 1992 to August 1993). The measured matric suction data indicates that the hydraulic gradient within the soil cover system is predominantly upward except for relatively short periods of heavy rainfall and snow melt in late fall and early spring.Key words: waste rock, soil cover, instrumentation, monitoring, unsaturated soil, soil-water characteristic curve.
In situ multiphase fluidization ("upflow washing") for the remediation of hydrocarbon contaminated sands
Authors: Niven Robert K , Khalili Nasser
Published: April 2011

A new in situ remediation method is described, "upflow washing," in which contaminants are flushed to the surface within an in situ fluidized zone produced by a jet inserted into a granular formation. The suitability of the method for LNAPL (light non-aqueous phase liquid) remediation is examined by experiments on diesel-contaminated soils within column and tank settings. The experiments indicate significant reductions in diesel levels (96-99.9%) may be achieved by fluidization with water and gas (gas-liquid upflow washing, GLUW) for a wide range of initial diesel concentrations (10 000 to 150 000 mg/kg) and for soil fines contents of 0 to at least 10%. Final diesel levels of <1000 mg/kg in a uniform fine sand and <200 mg/kg in clayey sands can be achieved. The efficiency is much higher than that of fixed bed flushing (simulated pump-and-treat), as the method overcomes the trapping of NAPL ganglia. Fludization with water alone (liquid upflow washing, LUW) is less effective than fixed bed flushing in the uniform sand, but approaches that of GLUW in clayey and silty sands. The results are explained by theoretical analysis of the removability of isolated NAPL droplets and mixed solid - NAPL particles from a fluidized bed due to buoyancy and elutriation, which may be represented using a "removability regime map" for the diesel-water-sand system.Key words: fluidization, in situ, remediation, NAPL, diesel.
The behavior of a compressible silty fine sand
Authors: Huang An-Bin , Hsu Huai-Houh , Chang Jia-Wei
Published: April 2011

Publications associated with sands are often limited to clean (i.e., little fines content), uniform, uncemented silica or quartz sand. On the other hand, the importance of mineral content, particle shapes, as well as gradation to the behavior of sand has long been recognized. Although systematic studies of sands other than clean quartz sand have been limited, there is increasing attention being paid to sands with an appreciable fines content. Because of a major construction project, extensive field and laboratory experiments were performed on a silty fine sand from Mai-Liao, which is located on the central west coast of Taiwan. Results show that Mai-Liao Sand (MLS), a silty sand, can be significantly more compressible than clean quartz sand under static load. The particles of MLS have moderate strength, and significant crushing can be induced by triaxial shearing. As a result, MLS has low dilatancy and a relatively small range of peak friction angles. Cone penetration tests in MLS were conducted in a calibration chamber. Analyses of the data indicate that interpreting cone tip resistance in MLS using methods developed based on clean quartz sand without considering the differences of compressibility can be unrealistic. This paper documents results of the experimental studies on MLS.Key words: silty fine sand, strength, dilatancy, compressibility, crushing, in situ test.
Identification expérimentale d'une loi de tassement du ballast
Authors: Guérin Nathalie , Sab Karam , Moucheront Pascal
Published: April 2011

Le ballast et le rail sont les composants majeurs intervenant dans la qualité de l'infrastructure ferroviaire. Or, le comportement du ballast demeure mal connu. Pour identifier une loi de tassement du ballast dans le plan vertical, un essai à échelle un tiers, intitulé « Microballast », est proposé. Pour cela, des lois de similitude décrivent le passage des grandeurs associées au modèle réel à celles du modèle réduit. Elles sont basées sur la conservation du matériau ballast et la conservation des champs de contraintes au sein de l'éprouvette. L'éprouvette de ballast est soumise à un chargement vertical reproduisant la charge appliquée sur le ballast lors du passage d'un bogie de train à grande vitesse (TGV). Les résultats de cet essai servent à établir la loi de tassement du ballast qui relie un incrément de tassement à la déflexion élastique de l'ensemble formé par le ballast et le sol sur lequel il repose. Les paramètres intervenant dans le chargement, la qualité du sol supportant le ballast et l'épaisseur de la couche de ballast sont discutés. Mots clés : voie ferrée, ballast, comportement mécanique, chargement cyclique, tassement.
Numerical simulation of pullout response for planar soil reinforcements
Authors: Gurung N , Iwao Y
Published: April 2011

This paper presents a series of numerical simulations for laboratory and field pullout tests. A nonlinear differential expression for interface pullout from simple equilibrium of forces and hyperbolic interface model for shear displacement variation along the length of the planar reinforcement is utilised. Finite difference numerical method and nondimensional expressions are adopted for wider application. The relative stiffness and relative displacement parameters are defined and related to the interface pullout interaction mechanism. A parametric study to develop computer-simulated interface design charts for a practical range of relative stiffness and relative bond resistance is theoretically illustrated. The pullout model is capable of simulating the responses of inextensible as well as highly extensible planar reinforcements. The model responses compared satisfactorily with the available theoretical and experimental pullout test results for steel straps, polymer strips, geotextiles, geomembranes, nylon geosynthetics, and geogrid reinforcements.Key words: geosynthetics, extensible reinforcement, numerical simulation, parametric study, pullout testing, reinforced soil.
Freeze-thaw dewatering of oil sands fine tails
Authors: Dawson R F , Sego D C , Pollock G W
Published: April 2011

Laboratory and field experiments demonstrate that substantial dewatering occurs when the waste clay from oil sands operations is subjected to one cycle of freeze-thaw. The enhanced permeability resulting from the freezing process causes further dewatering and accompanying strength increases during post-thaw consolidation. The findings presented here were guided by a number of different materials handling scenarios which take advantage of the freeze-thaw process and are driven by the appropriate geotechnical, geochemical, and geothermal input parameters. Different conceptual design scenarios are examined to demonstrate how this process might be feasibly implemented at the commercial scale. Emphasis is placed on the large-scale requirements, sensitivity to input parameters, and the coupling of the continuing applied research with the conceptual materials handling models. The latter point is of generic interest to those involved in mine waste management.Key words: mine wastes, freeze-thaw, volume reduction, disposal, large strain consolidation.