摘要:

The ultimate lateral resistance and the lateral deflection at working loads of rigid vertical walls and piles with a free head subjected to horizontal load and embedded in two-layered soils of sand and clay have been investigated. Part 1 deals with the behaviour of rigid walls, and the analyses are compared with the results of model wall tests in layered soils. Part 2 treats the behaviour of rigid piles, and the analyses are compared with the results of model tests on piles and pile groups in layered soils and some field case records.

ISSN:0008-3674    

DOI:10.1139/t81-021

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The selection of the type of drilling or production platform appropriate to a particular off shore site depends, chiefly, upon the likely severity of the marine environment, the nature of the seabed, and the geotechnical properties of the underlying soils and whether there exists a requirement for on-site oil storage. Although these physical factors have all played important roles in shaping the evolution of offshore structures, particularly in the North Sea, economic considerations and the national preferences of client companies have on occasion been decisive.This paper traces the evolution of offshore oil production structures for the North Sea with particular emphasis on the role played by geotechnical engineering during the conception, design, and construction of some of the largest movable structures in the world.

ISSN:0008-3674    

DOI:10.1139/t81-022

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Since the commencement of mining at the strip coal mine at Goonyella, Queensland, Australia, serious stability problems have been experienced in both the spoil piles and the highwalls. A collaborative investigation was commenced in 1974 and the significant factors influencing stability have now been defined. This paper outlines the results of field and laboratory studies associated with the investigation and describes the various numerical methods used to analyse stability. The main conclusions, which are similar for both the spoil piles and the highwalls, are that the failures generally occur along two or three planar surfaces; that the shear strength in the basal areas is controlled by the sensitivity of the materials to moisture and shear strain prior to failure; and that tensile cracking due to stress relief and blasting is the dominant factor in the upper or escarpment areas. Possible control and remedial measures are discussed briefly.

ISSN:0008-3674    

DOI:10.1139/t81-023

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Recent laboratory hydraulic fracturing experiments have shown that fluid penetration into the rock mass adjacent to the borehole being pressurized has a significant influence on the magnitude of the breakdown pressure. One factor affecting the degree of penetration of the pressurizing fluid is the permeability of the rock mass, which in turn is a function of the state of stress present in the rock mass. To study this permeability–stress relationship, a radial permeameter was constructed and three rock types tested. Derived expressions show that during radially divergent and convergent flow in the permeameter, the state of stress in the rock specimen is tensile and compressive respectively. The radial permeameter test results show that the permeability of rock increases significantly under tensile stress conditions and reduces under compressive stress conditions. The results from this study were used to develop a conceptual model which explains the dependency of breakdown pressure levels on the pressurization rate.

ISSN:0008-3674    

DOI:10.1139/t81-024

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Historical landslides in the urbanized Vancouver region, southwestern British Columbia, have almost commonly occurred along escarpments within and at the margins of gently rolling upland surfaces underlain by Pleistocene unconsolidated sediments. The most common and most destructive landslides are debris avalanches and debris flows. They are triggered by intense autumn and winter rainstorms, when water infiltrates and saturates the surficial layer of weathered colluvium. After failure the veneer of debris gains momentum and picks up additional soil and uprooted vegetation. Debris avalanches may temporarily block gullies swollen with runoff water, thus changing into rapidly moving debris flows.A severe rainstorm in December 1979 was accompanied by destructive debris avalanches and debris flows in urban areas in the vicinity of Vancouver. A search of local newspapers and meteorological records back to 1900 indicates that this event was not unique, for at least 26 other comparable storms have triggered landslides in the Vancouver region during this century. Thus it is likely that landslides similar to those of December 1979 will occur repeatedly in the future. The danger of such landslides to life and property will grow if potentially hazardous sites are urbanized without appropriate protective measures.

ISSN:0008-3674    

DOI:10.1139/t81-025

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Direct simple shear tests have been conducted on a variety of reconstituted frozen soils and on ice in order to investigate the load transfer process associated with the adfreeze bond to piles, and to obtain creep properties of frozen soils. The test develops uniform shear strain between plates of different roughnesses provided the applied shear stress is less than the ad freeze strength of the pile. Tests have been performed at about −1°C for durations up to 45 days to explore ultimate creep rates. The long-term flow of ice in this test is consistent with previously published power law relations. The experimental data on the frozen soils indicate how creep rate tends to decrease with increasing density except for dirty ice, which displays creep rates slightly higher than those observed for pure ice.

ISSN:0008-3674    

DOI:10.1139/t81-026

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

This contribution presents a recent review of equipment and field techniques applicable to offshore seabed survey work and site investigation, with particular reference to Canadian interests.During the past decade many advances have taken place in equipment design and in under standing the behaviour of mechanical sampling devices and the inadequacies of data derived from samples physically removed from the site. There has been a significant improvement in the ability of both remote and contact sensory systems to characterize and resolve differences in the physical and mechanical properties of bottom sediment materials, and the use of even simplistic remotely sensed data, if rapidly obtained and processed, offers significant economic advantages. The trend towards greater use ofinsitutests will continue.The application of facies concepts, in planning field surveys, may provide opportunities for improved sample recovery, reduced sampling, and greater confidence in data interpretation.Data, comments, and examples refer to a number of Canadian situations, for example, deep ocean studies, shelf studies (such as on the Labrador Shelf, the Scotian Shelf, and the Beaufort Sea), inter-island studies in the Canadian Arctic, and inland studies in the Great Lakes and smaller lake and river systems.

ISSN:0008-3674    

DOI:10.1139/t81-027

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A convenient and economical finite layer method of analysing the behaviour of footings on a non-homogeneous soil is outlined. This method of analysis is used to investigate the elastic response of strip footings for a wide range of soil profiles involving a weathered crust overlying a main deposit. The stiffness of the crust is considered to be either constant or to decrease with depth while the stiffness of the underlying deposit increases with depth.The effect of layer depth, crust depth, and the rate of variation of stiffness within the crust and the underlying soil are examined. The influence of this non-homogeneity upon settlement profile, differential settlement, and consolidation settlement are discussed and the results obtained from this detailed analysis are compared with results obtained from the approximate use of existing homogeneous elastic solutions.The results of this study are presented in the form of influence charts which may be used in hand calculations to estimate the settlement of footings for a wide range of practical cases. The applicability of the solutions and the determination of soil parameters is briefly discussed.

ISSN:0008-3674    

DOI:10.1139/t81-028

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The behaviour of circular footings resting on a non-homogeneous elastic soil with a crust is investigated. The stiffness of the crust is assumed to be either constant or to decrease with depth, whereas the stiffness of the underlying soil increases linearly with depth.Consideration is given to the effect of layer depth, crust depth, and the rate of variation of stiffness within the crust and the underlying soil upon the settlement profile. The behaviour of circular footings is then compared with that of strip footings and the relative importance of the crust and the underlying soil parameters is discussed.The influence of cross-anisotropy upon footing response is briefly examined and the effects of neglecting anisotropy are indicated for a number of soil profiles.The results of this study are presented in the form of influence charts which may be used in hand calculations to estimate the settlement of circular footings for a wide range of practical cases. The use of these charts is illustrated by means of a worked example.

ISSN:0008-3674    

DOI:10.1139/t81-029

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The one-dimensional consolidation of a thick clay layer, initially consolidated fully under its own weight, is considered. Account is taken of the variation of the coefficients of permeability and compressibility as consolidation proceeds. To render the theory consistent finite strains are permitted. Comparisons with conventional theory, in a practical example, show that nonlinear finite strain theory predicts the progress of consolidation settlement to be substantially swifter than indicated by conventional theory, although the dissipation of excess pore pressure may be slower. The consequences of this indicate that conventional consolidation theory has the potential to seriously underestimate the excess pore water pressure in a soft layer. As a result, the estimated shear strength would, if an effective stress analysis were used, be overestimated; a potentially unsafe design could emerge.

ISSN:0008-3674    

DOI:10.1139/t81-030

出版商:NRC Research Press    

年代:1981

数据来源: NRC