ISSN:0008-3674    

DOI:10.1139/cgjauthor99

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The properties of marine deposits in a nearshore seabed at a land reclamation site in Hong Kong were investigated. A variety of laboratory and in situ tests were conducted to define the geotechnical and consolidation characteristics of the marine deposits. The reliability and applicability of various laboratory and in situ testing techniques in evaluating the coefficient of consolidation were examined. Coefficients of consolidation were calculated from conventional oedometer tests, large-diameter (250 mm) Rowe cell tests, field permeability tests, and piezocone dissipation tests. Three techniques were adopted to evaluate the horizontal coefficient of consolidationchfrom the results of in situ piezocone dissipation tests. Results from in situ pore pressure dissipation tests are compared with those from large-diameter Rowe cell tests performed on undisturbed samples under both vertical and horizontal drainage conditions and in situ permeability tests to provide reference values of the vertical coefficient of consolidationcvandch. The engineering implications, particularly those related to land reclamation work in the nearshore environment, of various laboratory and field tests are discussed.

ISSN:0008-3674    

DOI:10.1139/t99-063

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Several first-time landslides occurred in the Maskinongé area, Quebec, during the summer, which is rather unusual. They have been studied in detail, including a site investigation. The results show the following: (i) piezocone tests indicate that the clay mass close to the slopes of precarious stability is softened; (ii) the failure surface develops within the softened zone; and (iii) three of the four landslides occurred during the summer period when pore pressures are low, indicating that failure could be due to fatigue phenomena

ISSN:0008-3674    

DOI:10.1139/t99-069

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Recent methods to calculate the lateral earth force on a retaining wall have involved the method of slices and limit equilibrium concepts. An important issue in formulating the solution is the selection of an appropriate interslice force function (i.e., the ratio of the shear force to the normal force of vertical slices along the slip surface). This paper proposes interslice force functions that can be used to compute the active and passive earth forces in conjunction with the limit equilibrium method. An example problem involving a vertical wall with a horizontal backslope is analyzed using the general limit equilibrium (GLE) method and the proposed interslice force functions. The procedure recommended to compute the lateral earth force and the point of application of the force is outlined. The computed lateral earth forces, and the point of application, are compared with those from the classical solutions. For the active case, reasonable results were obtained when using an interslice force function that varies linearly from the starting point of the slip surface (at some distance from the wall) to the end point of the slip surface (adjacent to the wall). For the passive case, reasonable results were obtained when using an interslice force function that remains at zero from the starting point of the slip surface (at some distance from the wall) to the midpoint of the slip surface and then varies linearly from the midpoint of the slip surface to the end point of the slip surface (adjacent to the wall).

ISSN:0008-3674    

DOI:10.1139/t99-065

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The undrained shear strength behaviour of kaolinitic soils is shown to be quite opposite to that observed for montmorillonitic soils under different physico-chemical environments. The mechanism controlling the undrained shear strength behaviour of soils is a function of clay mineralogy of the soils. The present investigation proposes two mechanisms to explain the contradictory behaviour of kaolinitic and montmorillonitic soils under undrained conditions. The undrained shear strength of kaolinitic soils is a result of the net attractive forces and the mode of particle arrangement as governed by the interparticle forces, whereas that of montmorillonitic soils can be attributed to the viscous shear resistance of the double-layer water. The validity of the proposed mechanisms is confirmed by the results of the present investigation and those in the literature.

ISSN:0008-3674    

DOI:10.1139/t99-071

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

A two-dimensional model retaining wall system was developed to investigate the effect of the bending rigidity of a wall, supported at the top and bottom, on the lateral pressure distribution at completion-of-backfilling condition. A total of 120 000 pieces of 1.96 mm diameter stainless steel rods were placed piece by piece behind the 500 mm high walls in a parallel and dense stack. Ten two-component load cells were mounted to the inner face of the wall to obtain simultaneously normal and shear stresses acting on the wall. The stress-deformation characteristics of the steel-rod assembly and the friction angle between the steel rods and the stainless plate were investigated thoroughly to provide parameters of the backfill material used. Four types of walls with different bending rigidities were employed. The deflections at the half-height of the wall at the moment of completion of backfill ranged between 0.03 and 4.6 mm. A parameterRr, the relative degree of deflection at the half-height of the wall, was used to evaluate the lateral pressure distribution on the walls for their at-completion conditions. Both the lateral pressure coefficients and the patterns of lateral pressure distribution on the walls were strongly related toRr.

ISSN:0008-3674    

DOI:10.1139/t99-070

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

This paper is focused on seepage erosion causing liquefaction processes and rapid slope failures. One case history, which occurred along an old fluvial terrace in the Po Plain (northern Italy), is presented. The failure was the final consequence of a concentrated flow induced by the incisions due to tractor edged-blade-wheels cutting through the soil layer sealing the bottom of a flooded rice field. To clarify the evolution of the seepage and the erosion phenomena which preceded and characterized the collapse, numerical analyses and some experimental tests on small-scale models have been performed. The problems associated with the hydraulic and mechanical description of localized water flows in unsaturated soils, the three-dimensional conditions of the failure mechanism, and the liquefaction phenomenon are discussed.

ISSN:0008-3674    

DOI:10.1139/t99-062

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Centrifuge lateral load tests were performed on single battered piles at five pile inclinations founded in both medium-dense (relative density Dr = 55%) and loose (Dr = 36%) sands. The effects of pile batter and soil density on lateral resistance were studied. Pile batter had significant effects in dense sands but minor effects in loose sands. Based on the test results, nonlinearp-ycurves, wherepis the soil resistance in unit length andyis the lateral deflection of the pile, were developed for single piles at any angle (positive or negative) and sand density. The developedp-ycurves were subsequently used with a Winkler model (COM624, LPILE, FLPIER, etc.) to predict all the test results with reasonable accuracy.

ISSN:0008-3674    

DOI:10.1139/t99-072

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Large-scale marine reclamation has taken place on soft Hong Kong marine deposits (HKMD). More and more reclamation is to be undertaken due to the rapid development of infrastructures and housing projects. Properties and behavioural parameters (e.g., consolidation parameters) of HKMD are required for the design of reclamation or foundations on HKMD. The behaviour of HKMD is affected by clay content and other factors. This paper presents results dealing with the (i) composition (content of clay, silt, and sand), (ii) index properties, (iii) behaviour during oedometer consolidation, and (iv) strength and deformation behaviour in triaxial compression for HKMD deposits with different clay contents. Correlations of the behavioural parameters with clay content and index properties are obtained, presented, and discussed. The correlations and parameter values obtained in the present study follow the same trend as those published in the literature. Limitations on the application of these correlations are pointed out.

ISSN:0008-3674    

DOI:10.1139/t99-068

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Based on the observation that deposits of large rock avalanches consist predominantly of intensely fragmented rock debris, it is proposed that the processes of rock fragmentation are significant causes of the peculiar distribution of mass in these deposits, and of the correspondingly long runout. Rock fragmentation produces high-velocity fragments moving in all directions, resulting in an isotropic dispersive stress within the translating rock mass. A longitudinal dispersive force consequently acts in the direction of reducing mass depth and tends to cause the rear part of the avalanche to decelerate and halt and the front part to accelerate. The result is greater longitudinal spreading of the travelling mass compared with nonfragmenting granular avalanches. The longer runout results from this additional fragmentation-induced spreading.

ISSN:0008-3674    

DOI:10.1139/t99-067

出版商:NRC Research Press    

年代:1999

数据来源: NRC