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This paper presents the results of field tests performed to investigate the installation effects of pre-bored grouted planted (PGP) pile in deep clayey soil. The variation of horizontal soil displacements, excess pore water pressures and lateral soil pressures was measured in the PGP pile installation process. The test results show that the drilling and grouting process induced large horizontal soil displacements in the soil within a radial distance of 2 d (d is pile diameter), and the maximum horizontal soil displacements induced by the drilling and grouting process were smaller than 15.9 mm when the radial distance reached 4–5 d. Moreover, the horizontal soil displacements decreased along the soil layer depth, as the superficial soil layers were of small deformation modulus and lateral soil pressure. The drilling process brought large excess pore water pressures in the soil when the radial distance was less than 3 d, and the excess pore water pressures induced by the drilling stage were all less than 55 kPa when the radial distance reached 4–6 d. The drilling process also induced some lateral soil pressure increases in the soil within a radial distance of 3 d, while the measured maximum lateral soil pressure increases were smaller than 10.9 kPa when the radial distance increased to 4 d. On the whole, the excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile were much smaller than that induced by the installation of driven PHC pile. Moreover, the horizontal soil displacements, excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile all recovered rapidly after the installation of pile, as the cemented soil in the pile hole was in liquid state after the drilling and grouting stage. [ABSTRACT FROM AUTHOR]

Despite the advancement of the knowledge of unsaturated soil behaviour developed over the past decades, the understandings remain largely at the macro or element scale. Existing testing systems allow simultaneous in situ loading and X-ray imaging to facilitate the studies at micro or pore scale, but the soils of concern are normally two-phase (i.e., dry or saturated). This paper develops a new suction-controlled miniature triaxial apparatus for studying the micro-hydro-mechanical behaviour of three-phase unsaturated soils via in situ quantification of the evolutions of soil microstructures, aided by micro-X-ray computer tomography imaging. The apparatus can independently control combinations of net mean stress and matric suction whilst permitting high-resolution full-field imaging of the entire samples through the image analysis via methods of pore network modelling and discrete digital image correction. Results reveal that at equilibrium, suction at the "transition zone" of the soil does not necessarily mean to have both the air and water phases continuous, as otherwise recognized at the element scale. This phenomenon leads to nonuniform distributions of local void ratio and degree of saturation. Post-peak strain localization and shear band development are explained by the movements of pore fluid and the associated influences on local soil void ratio change. [ABSTRACT FROM AUTHOR]

The p–y method as a simplified analysis tool has been widely used to analyze the behavior of laterally loaded piles. This paper develops a novel cyclic p–y elastoplastic model within the framework of the single-surface bounding surface theory. The model can capture the soil stiffness degradation during cyclic loading by incorporating the cumulative plastic displacement to an interpolation function of the elastoplastic resistance coefficient. The model is relatively simple with only four parameters that can be determined from standard soil properties and stress–strain responses measured in direct simple shear tests. The performance of developed model is validated by predicting the cyclic lateral response of piles installed in soft clay during field and centrifuge tests published in the literature. The model can reliably simulate monotonic and cyclic responses of piles under different lateral loading patterns, and capture main characteristics of the pile-head load–displacement curve, such as nonlinearity, hysteresis, displacement accumulation, and stiffness degradation. It can also predict the evolution of the lateral deflection and sectional bending moment along the pile during cyclic loading. [ABSTRACT FROM AUTHOR]

The geomechanical behavior of rock salt has been investigated extensively over the years. Experimental studies have identified distinctive features associated with nonlinear inelastic response that shows strong time and loading history dependencies. In this paper, a relatively simple constitutive model is presented and implemented into the numerical code FLAC, and then applied to analyze the time-dependent behavior of excavations in salt mines. The unified creep-plasticity model includes an internal state variable (ISV) with an evolution law that induces progressive strain hardening (SH) until a steady state is reached. Numerical analyses are performed with the proposed ISV–SH model to evaluate material parameters, based on creep test results on natural rock salt, and to simulate the response of a circular opening and of rectangular mining excavations created in sequence. The results are analysed and compared with those obtained with the well-known Norton power law equation, commonly used in salt mine engineering. The time-dependent calculation results illustrate key aspects of rock salt behavior and highlight the major influence of transient inelastic behavior and stress redistribution on the response of underground openings. The proposed modelling approach constitutes an advantageous alternative to analyses based on stationary creep laws, often used in rock salt mining operations. [ABSTRACT FROM AUTHOR]

This paper presents the results of a series of cyclic nonsymmetrical thermally loaded model-scale tests conducted on floating pile groups, with and without a rigid cap in saturated clay. The energy pile in each group was subjected to 10 two-way (heating–cooling) thermal cycles with an amplitude of 15 °C to investigate the potential effects of a rigid cap on the thermomechanical behavior of energy pile groups. It was found that the rigid cap restrained the expansion/contraction of the energy pile in response to temperature change and reduced its irreversible settlement, resulting in a lower differential settlement between the energy and nonenergy piles. Consequently, a lower tilting was observed in the pile group with a rigid cap. In addition, the thermally induced axial load was significantly increased (especially in cooling mode) due to the restriction of a rigid cap. The thermomechanical load transfer profile of the energy pile was also affected by it, resulting in the downward transmission of shaft resistance. [ABSTRACT FROM AUTHOR]

Fines migration associated with the multiphase flow in the exploitation of hydrate-bearing sediments (HBS) usually induces local clogging and sand production around wells, and thus its behavior with multi-field coupling is of vital importance but still poorly discovered. This paper establishes a coupled thermo-hydro-mechanical-chemical (THMC) model incorporating fines migration in HBS from micro- to macro-scale. Two typical hydrate pore habits, i.e., grain coating and pore filling, are simulated with the discrete element method (DEM) under different depressurization modes, water flow is simulated using computational fluid dynamics (CFD), and heat transfer and chemical reactions are also considered in coupled CFD-DEM simulations. Two distinct fines migration modes and their consequence on the mechanical and hydromechanical properties are revealed. For the grain-coating habit, the coarse particle size reduction induced by hydrate dissociation under an intense depressurization decreases the constriction size, increasing the local pore-clogging probability and reducing the growth rate of the hydraulic conductivity. Conversely, the fine particle size reduction in the pore-filling habit facilitates fines migration and thus sand production, with hydromechanical properties of HBS evolving oppositely compared to the clogging case. [ABSTRACT FROM AUTHOR]

The main objective of this paper is investigation of clayey soil setup effects on axial "resistance" and "stiffness" of small-scale piles with special attention on "overconsolidation ratio" (OCR) and "installation method". A consolidation chamber is developed and an instrumented model pile is either driven or jacked-in through saturated consolidated Kaolinite clay at different OCRs of 1.2 (normally consolidated, NC) and 4.8 (over consolidated, OC). The pile was static load tested at different time intervals of 1 h through 90 days. Higher pore pressures are induced during pile installation in NC compared to OC clay. The frictional resistance of OC soil is higher than NC at end of drive as well as end of setup in both driven and jacked-in piles. The frictional resistance of jacked-in piles is greater than driven piles at end of drive, but due to higher rate of setup, the long-term frictional resistance of driven piles is shown to be greater, attributed to more disturbance of the soil during installation of driven piles. Attempts are made to differentiate between the contributions of dissipation of excess pore pressure and non-pore pressure components for each consolidation condition and pile installation method. A relation is proposed to quantify the pile stiffness variations over time due to soil setup. [ABSTRACT FROM AUTHOR]

The performance of a 56 m deep circular excavation supported by a double-wall system, consisting of an inner circular diaphragm wall and an outer rectangular cut-off wall, in Shanghai soft ground is studied in this paper. The surveyed data (e.g., lateral wall deflections (δh), horizontal displacement of soil (δs), ground surface settlement (δv), soil rebound (δv+), earth pressure (P), pore water pressure (Pw), and soil stress path) are systematically investigated. The results show that the maximum lateral wall deflections are 0.002% ∼ 0.03% of the excavation depth (He). The maximum ground surface settlement (δvm) is generally larger than δhm, which is located at 0.4 ∼ 0.6He. Moreover, an innovative formula is proposed to estimate the ground settlement. It is able to distinguish various characteristics of surface settlement in different zones of the settlement profile. The ground surface settlements are mainly induced by surcharge loading and continuous excavation, and they are related to the change in confined water level. The lateral earth and pore water pressures in the active zone are relatively insensitive to the excavation, while the correlation becomes obvious in the passive zone. The findings from this study can be helpful to the design of other similar deep excavations in soft clay. [ABSTRACT FROM AUTHOR]

The design of shallow foundations typically proceeds by using the load and resistance factor design (LRFD) methodology to avoid various limit states with some probability. This paper looks at the sliding limit state of shallow foundations, and the sliding resistance factors required for the LRFD approach are estimated using reliability analyses of surface strip foundations. Cohesive and frictional soils are separately studied under wind loading conditions. Monte Carlo simulations are used to estimate the sliding failure probability of foundation designs on cohesive soils, and an analytical method is developed for frictional soils. The results indicate the existence of a "worst case" correlation length for cohesive soils, and the sliding resistance factor required to achieve target maximum lifetime failure probabilities is around 0.4–0.65 for moderate soil variability. For frictional soils, the required sliding resistance factor is about 0.5–0.85 for νϕ′ = 0.15. Overall, the sliding resistance factors recommended here agree well with the resistance factors of ϕgu = 0.6 for cohesive soils and ϕgu = 0.8 for frictional soils stipulated by geotechnical LRFD code provisions in Canada. The analyses can be used to estimate the reliability of current designs and can also aid the calibration of geotechnical design codes. [ABSTRACT FROM AUTHOR]

Determination of the critical state of tailings is essential to the stability analysis of tailings dams, especially to assess the susceptibility to flow liquefaction failures. In contrast to the peak resistance, which can be determined in triaxial tests at relatively small strains, the critical state is often reached at higher strains. Therefore, determining the critical state in triaxial extension tests is more difficult than in compression tests because the concentration of stresses and strains in extension tests is more severe and usually inevitable, resulting in necking that may greatly affect the computed deviatoric stress and void ratio (if the test is drained). This paper presents a simple and cost-effective method of necking correction using photography. The method was used in the determination of the critical state in drained triaxial extension tests. A sample of silty sand tailings obtained from the reservoir of the Fundão dam two years prior to its collapse was used. The critical state friction angle was approximately the same in compression and extension, showing that the proposed method is promising as many authors consider that the critical state friction angle is the same in these two conditions. [ABSTRACT FROM AUTHOR]

Soft soils often contain important fractions of fines and organic matter which are characterized by high shrinkage potential. Investigating the shrinkage behaviour of soft soils is of primary importance to assess the durability of infrastructures exposed to climatic stresses. This paper investigates the influence of soil fabric on the shrinkage properties and the change in the microporosity structures over drying. Soil shrinkage tests were performed on Shenzhen soft clay (SZ soft clay) and fibrous peat. The effect of the initial fabric was investigated by comparing the samples at natural and reconstituted states, and the reconstituted peat samples with different fibre contents. To assist in the interpretation of the results, microstructural changes in the soil fabric were investigated by mercury intrusion porosimetry, scanning electron microscopy, and micro-CT scan. As the water gradually drains from the multilevel pores, different drying stages were identified. Pore refinements occurred during the drying process, accompanied by a progressive reduction in the peak pore entrance. Contrary to SZ soft clay, intensive shrinkage occurred in the last stage of fibrous peats, due to the collapse of interpores and cracks created during drying. The results showed that the magnitude of the intensive shrinkage increased with the fibre content. It suggests that fibres act as an unstable element in peat upon drying. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The stress crack resistance (SCR) and standard oxidative induction time (Std-OIT) reduction of high- density polyethylene (HDPE) geomembrane (GMB) fusion seams is examined for a 12-year old 1.5 mm HDPE GMB when welded using nine welding parameter combinations. The GMB experienced a decrease in Std-OIT from 135 to 87 min between manufacturing and welding. Welding did not significantly decrease the Std-OIT in the heat-affected zone (HAZs). In general, individual seam SCR failure times fell between the notched and unnotched sheet, with adhered squeeze-out bead seams exhibiting individual failure times closer to the notched sheet and an average time until nominal failure (tNF) ∼21%–35% shorter than the unnotched sheet. Differences in tNF are attributed to residual stresses and (or) accelerated craze formation in seams with adhered squeeze-out beads. Non-adhered squeeze-out seams exhibited a slower tNF similar to that of the unnotched sheet, indicating a seam tNF less than that of the sheet may not be intrinsic to all HDPE fusion seams. High sheet temperatures at the time of welding and higher heat-applied welding parameters are thought to increase the likelihood of squeeze-out bead adherence. This paper shows that squeeze-out adherence can have a deleterious effect on seam SCR. [ABSTRACT FROM AUTHOR]

This paper presents results of a series of monotonic and cyclic direct simple shear laboratory tests performed on reconstituted samples of two silty sands and one sandy silt. The laboratory program aimed to determine the cyclic shear strength and deformation characteristics of soils to be used in the offshore wind turbine foundation design. Various cyclic contour diagrams including cyclic shear strength and average and cyclic shear strains for different number of cycles were provided. The effect of strain rate for drained monotonic tests and overconsolidation ratio effect on both monotonic and cyclic properties were discussed. This study indicated that the fines content plays an important role in static and cyclic shear strength of silty soils, in addition to mineralogy and coefficient of uniformity. [ABSTRACT FROM AUTHOR]

The paper deals with three issues relevant to the application of TDR methods for monitoring water content in compacted clay soils: (i) the dependence on dry density, (ii) the ability to monitor changes in water content in clay soil approaching saturation, and (iii) difficulties in performing efficient and reliable calibrations. A calibration scheme which inherently controls dry density of the specimen has been developed and applied. The methodology creates continuous calibration curves over a range of volumetric water content from a single test specimen. The new approach has been applied in monitoring the advance of a wetting front through a compacted swelling clay in a laboratory environment. [ABSTRACT FROM AUTHOR]

This paper presents realistic discrete element method (DEM) simulations of mixtures of sand and rubber grains. The shape of the grains and the deformability of the rubber are accounted for in the model. A set of 1D compression tests and triaxial compression tests are performed on samples with different rubber contents. It is shown that the model can accurately predict the mixture behaviour at macro-scale. The insights from a micro-mechanical analysis of force chain network, coordination number, and side-wall friction indicate that deformability plays a key role in exhibiting realistic behaviour. Finally, a new criterion is presented to determine the limits of sand-like and rubber-like behaviour. [ABSTRACT FROM AUTHOR]

Unsaturated soils with a high degree of saturation (HDS) are commonly encountered in marine and lacustrine sediments. In these soils, the gas phase generally exists in the state of discrete bubbles, which is sensitive to stress and temperature changes and can dramatically change the soil's engineering properties. This paper explores the thermal-induced behaviour of HDS soils using an efficient extended precise integration method (XPIM). Biot poroelasticity theory, extended to include thermal effects and compressibility of gas–water mixture, is employed to analyze the soil behaviour under non-isothermal conditions. Based on the Laplace–Fourier transform and Taylor series expansion, such problems can be solved by XPIM. The robustness of XPIM was confirmed by comparing the present results with analytical solutions and test data. Extensive parametric studies are undertaken to examine both the effects of soil grain thermal expansion and anisotropic permeability on soil behaviour and temperature effects on the degree of saturation (Sr). The thermal-induced variations in Sr are more pronounced with lower initial values (e.g., 90% compared to 99%). These quantitative results demonstrate the benefits of the proposed method, which proves to be extremely efficient and several orders more precise than conventional numerical approaches, with its precision limited only by the computational effort used. [ABSTRACT FROM AUTHOR]

The article provides information on the discussers' perspectives on the implications of the study of Xiong Zhang and Robert L. Lytton on the new modelling approach for unsaturated soils using independent stress variables. The author stated that the material properties Kvs and Kvp are not independent on each other. In addition, the selection of the parameters must consider the principle of elastoplasticity. Moreover, the discussers believe that an easy way to select Kvs and Kvp may be define the elastic and elastoplastic surfaces.

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article offers information on the R.M. Quigley Award is given out each year to the best paper published in "Canadian Geotechnical Journal (CGJ)" in the previous year and presents the abstracts of the winning paper as well as the three papers that were given Honourable Mention for the 2021 R.M. Quigley Awards.

This note presents the application of the mobilisable strength design (MSD) method to the monitoring results of the multi-propped excavation in the south area of the British Library Euston, constructed in a highly overconsolidated stiff clay deposit. The MSD method is an energy-based approach (a nonlinear finite-element method for a single-degree-of-freedom soil-wall system) introduced to develop a simplified design methodology that satisfies both ultimate and serviceability limit states. Wall displacement predictions based on the MSD method are compared with considerable field monitoring data. The sensitivity of the method to reasonable variations in input parameters is considered. A spreadsheet and python code demonstrating the MSD analysis from this paper are provided in the online supplement alongside details of the mathematical formulation. [ABSTRACT FROM AUTHOR]

In this paper, eight shear tests were carried out utilising a double shear with infilled shear interfaces after determining an appropriate experimental design and modified testing scheme. For this, two rock bolts, 20 and 30 tonnes, were tested with modified double shear testing apparatus at different pretension loads. The infilled test scheme was conducted with 5 mm thick sandy clay infilled shear interfaces. A 40 MPa small aggregate concrete was used for all samples to simulate the host rock. Based on the shear profiles, it was found that all samples followed a three-part failure profile consisting of elastic, strain softening, and failure regions. The results of double shear tests revealed that the 20 tonne rock bolt saw a significant overall decrease of approximately 30% in its failure displacement response as opposed to the 30 tonne samples, which saw a 6% increase. Also, it was concluded that the 30 tonne samples outperformed the 20 tonne rock bolts by up to 30%, irrespective of initial pretension settings. Comparing the physical failure characteristics of the samples found that both the 20 and 30 tonne samples exhibited the same response to increased pretension. As the pretension increased, the angle experienced at the hinge point also increased incrementally. [ABSTRACT FROM AUTHOR]

Integral bridges are built without expansion joints to avoid many of the persistent issues with joint degradation and maintenance problems regularly experienced by traditional bridges. In the absence of expansion joints, the cyclic thermal displacements of the integral bridge would be transferred unmitigated by the joints to the abutment resulting in accentuated soil–structure interactions. Previous studies have mainly focussed on the rotational mode of integral abutment movement while the translational mode of movement and backfill deformations have received much less attention. This paper presents the results of laboratory tests conducted on a semiscale (1:2) physical model, which was designed using dimensional analysis to achieve field stress and strain similarity with a full-scale 1.92 m high-prototype integral abutment. The comparative effects from five tests covering low to high cyclic translation amplitude on backfill surface settlement and heave, and lateral earth pressures behind the abutment were investigated over assumed 120 seasonal cycles. Asymptotic settlement depth of the backfill was obtained in each test. Full passive failure surface was observed when the cyclic translation amplitude of the test exceeded the threshold amplitude. The findings also suggest that the settlement depth seemed to be linked to the development of passive failure surface in the following sense—the asymptotic settlement depth in those tests which developed full passive failure surface would attain the same (ultimate) asymptotic depth; conversely, when the passive failure surface had not or only partially developed in that test, the asymptotic settlement depth was dependent on the cyclic translation amplitude, but it was less than the ultimate observed for full passive failure surface. Lateral earth pressure only stabilized to an asymptotic state for the test with the lowest cyclic translation amplitude during the 120 cycles. Shakedown limit state was observed for this case. At larger cyclic translation amplitudes, the lateral earth pressure did not stabilize but continued to evolve with the elapsed cycles, and shakedown limit state was not observed for these cases. [ABSTRACT FROM AUTHOR]

The shear stress–shear displacement relationship and shear strength parameters of the interface between the pipe and the surrounding soil are important for designing the jacking force. One most commonly used method to measure the shear strength of the pipe–soil interface is the direct shear test. This paper presents the results of a series of direct shear tests conducted in the laboratory on the pipe–soil interfaces for different moisture contents. Simultaneously, digital image correlation is used to supplement the research of the horizontal displacement field of the interface. The results show that the increase of normal stress will makes the interface more prone to strain hardening during the shearing process, and the influence of the change of specimen moisture content on the interface strain characteristics gradually weakens. The shearing process of the specimen mainly involved shearing contraction, and slight shear dilation occurs only when the moisture content is small. We proposed a unified model for describing the shear volumetric change caused by the combined action of moisture content and normal stress. The shear displacement field presents a layered distribution, which is related to the shear displacement corresponding to the shear stress. [ABSTRACT FROM AUTHOR]

This study offers an analytical solution for radial consolidation that captures the biogeochemical clogging effect in acid sulfate soils. Field sites and personal communication with industry practitioners have provided evidence of piezometers exhibiting retarded pore pressure readings that do not follow conventional soil consolidation and seepage principles when installed in coastal acidic floodplains. This retarded response together with a variation in pH, ion concentrations, and piezometric heads provided evidence of clogging at and around the piezometers. This paper uses the proposed biogeochemical clogging model, which is an analytically derived system of equations to estimate the excess pore water pressure dissipation of piezometers installed in clogging-prone acid sulfate soils. The inclusion of the total porosity reduction attributed to biological and geochemical clogging improves the predictions of the retarded dissipation of excess pore pressure, especially after about 1 year. This method is validated for two previously identified acidic field sites in coastal Australia, where piezometers measured a very slow rate of dissipation. It is concluded that this model has potential to accurately monitor the performance of critical infrastructure, such as dams and embankment foundations built on acidic terrain. [ABSTRACT FROM AUTHOR]

Fluid fine tailings (FFT) are a by-product of the process used to extract bitumen from surface-mined oil sands in Alberta, Canada. One of the FFT reclamation techniques involves mixing centrifuged FFT with coarse sand tailings to form non-segregating tailings (NST). While NST provides a means to achieve mine closure and reclamation objectives, the self-weight consolidation of NST takes years to complete in full-scale testing. This paper examines the use of bench-scale centrifugation for physical modelling of the consolidation of NST under centrifuge loading. A series of bench-scale centrifuge tests is conducted on NST specimens reconstituted at different sand–fines ratios (SFRs), along with conventional oedometer and standpipe tests. Micro-computed tomography technique with high resolution is used to quantify the internal structure of the centrifuged specimens, and to infer the segregation and consolidation behaviour of NST specimens under 1-g and centrifuge loading. No segregation is detected in NST specimens under 1-g loading, while segregation occurs in NST specimens with low SFRs under centrifugal loading. Thus, only consolidation behaviour of NST specimens without segregation is investigated and compared to those determined from conventional oedometer tests. Limitations on use of bench-scale centrifuge in physical modelling of consolidation behaviour of oil sands tailings are addressed. [ABSTRACT FROM AUTHOR]

Helical piles are used extensively for low and medium rise developments and are a popular foundation solution in cases where resistance to significant uplift loads is required. The ability to re-use helical piles and recent interest in their use as foundations in offshore wind and solar energy applications has renewed interest in improving existing design methods. This paper presents the results from field investigations in medium dense and dense sand that examine effects on the axial tension and compression capacity of varying the helix pitch, shaft diameter, advancement ratio and shaft tip geometry. The results from the 20 pile tests conducted (many of which included instrumentation) indicate low sensitivity to a range of the investigated parameters and a strong correlation of the capacity to the cone penetration test resistance. A design method based on these findings is proposed for typical helical pile geometries and is shown to provide predictions that are generally within 10 to 15% of the axial capacities reported for 30 other well documented pile tests reported in the literature. The method, referred to as UWASP-22, incorporates a simple means of estimating the load-displacement response of a helical pile as well as a formulation enabling prediction of the installation torque which is a common quality control measure for helical piles. [ABSTRACT FROM AUTHOR]

Excessive settlements or failure of piles observed in some Brazilian unsaturated soil sites indicates that the shaft resistance can vary with the seasonal variability of top soil water content, especially in the case of foundations of transmission towers or installed at the periphery of buildings, situations in which the soil is more susceptible to suction fluctuation due to the higher exposure to rainfall action. The objective of the research described in this paper was to provide field evidence with the purpose of alerting practising engineers and to help researchers to better understand the contribution of matric suction on pile capacity. For this aim, the seasonal variability of the shaft resistance of Continuous Flight Auger (CFA) piles in a typical Brazilian unsaturated tropical soil was evaluated by performing axial tensile load tests on eight instrumented CFA piles in different periods of the year. Soil suction was monitored throughout the period of tests, and the results indicate that the shaft resistance of the pile upper part varies considerably during the year and tends to decrease with decreasing soil suction. This work provides valuable insights into the application of unsaturated soil mechanics, which is usually disconnected to classical geotechnical practice. [ABSTRACT FROM AUTHOR]

The authors respond to R. Ganesh's discussion of their research paper "Analysis of Passive Earth Pressure Modification Due to Seepage Flow Effects." They thank Ganesh for his comments on the paper on the potential impact of seepage flow on the development of passive earth pressure behind a vertical retaining wall. They note that the paper used Fourier series expansion based on the boundary conditions in order to obtain an analytical solution to the flow field.

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The author comments on a study related to estimating the skeleton void ratio of grave-sand mixtures. Topics covered include how the study's method of relating the grain size distribution properties of the coarse and fine materials and the ratio of the diameter corresponding to 50% of the coarse materials and the fine materials seem to be promising, and observations related to the methods of analysis and definition of coarse and fine materials.

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ultimate parameter of interest in engineering design of compacted subgrades and support fills for highways, railroads, airfields, parking lots, and mat foundations is often the soil modulus. Modulus of compacted soils depends not only on dry unit weight and moisture but also on matric suction and soil structure (or fabric) resulting from the compaction process. However, these relationships in the as-compacted state (i.e., immediately after compaction) have not yet been extensively explored. This paper presents an experimental laboratory study of the shear modulus – matric suction – moisture content-dry unit weight relationship using three compacted subgrade soils. Compacted subgrade specimens were prepared over a range of molding water contents from dry to wet of optimum using enhanced, standard, and reduced Proctor efforts. A nondestructive elastic wave propagation technique, known as bender elements, was used to assess the shear wave velocity and corresponding small-strain shear modulus (Go) of the compacted subgrade specimens. The matric suctions were measured with the filter paper method. An empirical relation that takes into account the effect of compaction conditions is proposed for the Go – matric suction – molding water content relationship of compacted subgrade soils. Le paramètre ultime d’ingéniérie qui est d’intérêt dans le calcul d’ingénieur des infrastructures compactées et des remblais de soutien pour les autoroutes, les voies ferrées, les aéroports, les aires de stationnement, et les nattes de fondations est souvent le module du sol. Le module des sols compactés dépendent non seulement du poids volumique sec et de la teneur en eau mais aussi de la succion matricielle et de la structure du sol (ou fabrique) résultant du processus de compactage. Cependant, ces relations dans l’état tel que compacté (c.-à-d. immédiatement après compactage) n’ont pas encore été abondamment explorées. Cet article présente un étude expérimentale en laboratoire de la relation module de cisaillement – succion matricielle – teneur en eau – poids volumique sec en utilisant ces sols d’infrastructure compactés. Des échantillons d’infrastructure compactés ont été préparés dans une large plage de teneurs en eau de moulage en partant du côté sec au côté mouillé de l’optimum et en utilisant des efforts Proctor augmentés, standard, et réduits. Une technique de propagation d’ondes élastiques non destructives au moyen de languettes piézocéramiques a été utilisée pour évaluer la vitesse de l’onde de cisaillement et le module correspondant de cisaillement à faible déformation (Go) des spécimens d’infrastructure compactés. Les succions matricielles ont été mesurées avec la méthode du papier filtre. On propose une relation empirique qui prend en compte l’effet des conditions de compactage pour la relation Go – matrice de succion – teneur en eau de moulage des sols d’infrastructure compactés. [ABSTRACT FROM AUTHOR]

The article presents a response to the discussions made by Robert K. Barrett and Dov Leshchinsky on the authors' paper "The influence of facing stiffness on the performance of two geosynthetic reinforced soil retaining walls." They appreciate the comments raised by Barrett and Leshchinsky. In doing so, they clarify and elucidate a number of points related to the details and contingents of the test program described in the referring paper. Moreover, they provide various implications to current practice.

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)