摘要:

Geotechnical engineering is playing an ever-increasing role in the design and construction of pipelines within the Province of Alberta and elsewhere in Canada. There is a growing geotechnical awareness developing within the pipeline industry that has been spurred, to some extent, by the high costs of geotechnical remedial measures and increased environmental concerns.This paper presents major geotechnical problems that the pipeline industry faces in the design, construction, and operation of pipelines within Alberta. Geotechnical considerations involved in the location of pipelines and specific methods incorporated in the design to ensure the stability of slopes and prevent erosion are presented. Recent improvements of existing methods used in the control of surface and subsurface water within the right-of-way are outlined.There have been cases where an operating pipeline has developed geotechnical problems, such as slope instability or severe erosion, that necessitate some form of remedial action. Methods used to monitor potentially unstable right-of-way slopes and the specific remedial measures implemented are presented.

ISSN:0008-3674    

DOI:10.1139/t83-001

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

A technique suitable for the analysis of lined tunnels constructed in soft soil is described. This technique permits consideration of the soil-lining interaction, lining weight, and plastic failure within the soil. Particular attention is given to the simulation of loss of ground including the annular void created by the difference between the tunnelling machine and lining diameters. The analysis is used in a parametric study to identify potentially significant factors affecting the prediction of surface settlement due to tunnel construction. Consideration is given to the effects of elastic modulus; the distance between the tunnel and the underlying rigid base stratum; plastic failure; initial stresses; ground loss (including the annular void); and the injection of clay grout into the tailpiece void. The results of this analysis indicate that elastic anisotropy, ground loss, and clay grout injection are all important factors that are not usually considered in analyses. In particular, a parameter called the gap is defined in the paper and is used in an attempt to incorporate practical tunnelling experience into the calculation of surface settlement. Furthermore, it is shown that in predicting surface settlements underestimation of the true elastic modulus below the tunnel may decrease the predicted surface settlement and lead to overestimation of the invert heave. Underestimation of the modulus above the tunnel may also decrease the predicted surface settlement for situations where there is limited ground loss and extensive plastic failure.

ISSN:0008-3674    

DOI:10.1139/t83-002

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

A multichannel electric cone penetrometer was used to perform a variety ofin situtests in saturated deltaic deposits.Factors affecting the tip bearing, friction sleeve stress, and pore-water pressures and their interpretation are studied and discussed. Pore pressure measurements were essential to evaluate thein situtest results. The effect of rate of penetration is discussed and the concept of effective bearing introduced as an attempt to interpret cone bearing in undrained or partially drained soil. Field values of consolidation characteristics from pore pressure decay are compared with traditional laboratory consolidation test results on undisturbed samples.The advantages of continuous electric cone logging to evaluate soil stratigraphy are demonstrated. Field and laboratory test results are presented from a test site where stabilization was used to reduce liquefaction potential of hydraulically placed sand and silt. The importance of pore pressure measurements is demonstrated along with examples and recommendations for the location of the porous element.Keywords: static cone penetration testing,in situtesting, pore pressures, consolidation, stratigraphy, liquefaction.

ISSN:0008-3674    

DOI:10.1139/t83-003

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The reported research established the relationships among the compaction variables (dry density, water content, roller type, and number of passes) and the shearing behavior of a residual clay (St. Croix) from sandstone and shale. Compacted material was tube sampled from test pads, and subjected to two test series: unconsolidated-undrained (UU), and saturated consolidated-undrainedtriaxials. Both test series were run at various confining pressures to approximate the end of construction and long-term conditions for several embankment depths.The UU tests showed an increase in strength with an increase in density or a decrease in water content. For the as-compacted samples, significant volume changes occurred during shear. The volumetric strain at failure decreased with increasing prestress effected by the roller.In thetesting program, sample behavior after saturation under confinement was interpreted in terms of initial compacted conditions (and confinement). The effective stress strength parameters were functions of the compacted water content and void ratio. For a given initial void ratio, as the compaction water content increased,c′ increased anddecreased. The volumetric strain upon saturation varied with the compacted water content, dry density, compactive energy, and the level of confinement. Skempton'sAfactor at undrained shear failure was dependent upon the initial void ratio and the degree to which the sample had been prestressed by the roller.Statistically valid regression equations for these dependent variables, viz., as-compacted strength, percent volume change due to saturation and consolidation, Skempton'sAparameter at failure, and the effective stress strength parameters, were developed for field compacted St. Croix clay. Uses for such equations are given.

ISSN:0008-3674    

DOI:10.1139/t83-004

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The exact distributions of gravity stresses are obtained within slopes of finite height inclined at various angles, −β (β = π/2, π/3, π/4, π/6, and π/8), to the horizontal. The solutions are obtained by application of the theory of a complex variable. In homogeneous, isotropic, and linearly elastic slopes under plane strain conditions, the gravity stresses are independent of Young's modulus and are a function of (a) the coordinates, (b) the height, (c) the inclination angle, (d) Poisson's ratio or the coefficient of earth pressure at rest, and (e) the volumetric weight. Conformal applications that transform the planes of the various slopes studied onto the upper half-plane are analytically obtained. These solutions are also represented graphically.

ISSN:0008-3674    

DOI:10.1139/t83-005

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Influence diagrams are presented for the gravity stresses arising in excavated finite elastic slopes inclined at various angles, −β (β = π/2, π/3, π/4, π/6, and π/8), with respect to the horizontal. These influence diagrams are calculated for a value of the earth pressure coefficient at rest,K0, equal to 0.50. Several examples are worked out and adequately illustrate the application of the influence charts and of the general solution. Finally, the results obtained from the exact solution are compared with those published in the literature, which were obtained by means of numerical (finite element) and experimental (photoelasticity) methods.

ISSN:0008-3674    

DOI:10.1139/t83-006

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

In current methods for evaluating the liquefaction potential of soils, there are many uncertainties. A new approach to this problem is presented which shows that the macrofeatures of liquefaction and the earthquake damage modes of the ground can be predicted by analyzing aerial photographs that show the local microgeomorphic conditions of sites in strongly seismic areas. Using the new approach, a more reliable assessment of the liquefaction potential can be achieved, forming an important basis for the general planning and design of construction projects.This paper deals with the soil liquefaction potential problem using the vast area of the Tangshan earthquake as a model. The macroscopic patterns of liquefaction are divided into three categories, each with three subtypes. The mechanism of formation and the damaging effect of each pattern is discussed.There is evidence that, for given similar soil conditions, local geomorphic characteristics have a decisive effect on the macrofeatures of liquefaction and damage on the ground. This might provide a new basis for the avoidance of liquefaction-prone areas.

ISSN:0008-3674    

DOI:10.1139/t83-007

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Several analytical methods for the prediction of total heave of desiccated, expansive soils have been proposed for various geographic regions. The proposed method herein is based on a general theory for unsaturated soil. Thein situstress conditions, as assessed from the corrected swelling pressure and the required soil moduli, are deduced from the constant volume oedometer test.Verification of the proposed method was accomplished using data accumulated from the monitoring of movements of a floor slab in a light industrial building in north-central Regina, Saskatchewan. A leak in a water line buried under the floor slab resulted in a maximum heave of about 106 mm. Of the three final pore-water pressure distributions assumed, the one where pressure is constant with depth and equal to atmospheric pressure appears to be representative of the field conditions corresponding to the maximum measured heave. The measured heave represents 89% of the predicted heave for the zero pore-water pressure distribution. It is concluded that the proposed method of analysis, based upon a general theory for unsaturated soils, provides a practical method to accurately assess total heave.

ISSN:0008-3674    

DOI:10.1139/t83-008

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Drynoch landslide, located along the Thompson River, British Columbia, is a large volume, slow-moving earthflow. Geotechnically, it is classified as a zonal, infinite slope soil failure. Geological evidence indicates that it began to move approximately 3000–6000 years ago. Until the early 1800's, movement of the slide only affected the lifestyle of the early Interior Salish Indians, the inhabitants of the area. Since that time the landslide has had a direct influence upon the Cariboo Road built in the 1860's (which later became British Columbia Highway 1 and more recently the Trans-Canada Highway) and the Canadian Pacific and Canadian National railway lines. The history of Drynoch landslide is entwined with the geographic and geologic exploration of British Columbia and the development of the interior of the province. Over the past hundred years many geologists and engineers, some quite eminent, have recorded a number of theories on the possible cause and failure mechanism of this notable slide. Suggested and attempted methods of controlling the movement of Drynoch landslide have been numerous, and have met with various degrees of acceptance and success.

ISSN:0008-3674    

DOI:10.1139/t83-009

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Extensions are suggested to the generalized method of slices that is commonly used in slope stability analysis. It is shown that restrictions exist on the assumptions used to make the problem statically determinate. In addition, a numerical procedure has been developed to find the bounds to the factor of safety, subject to additional requirements of physical admissibility. As a result of these developments it has been possible to produce a revised computer program that appears to overcome the problems of convergence experienced by other programs in current use. Results obtained with this new analysis confirm the reliability of several methods of analysis used in practice.

ISSN:0008-3674    

DOI:10.1139/t83-010

出版商:NRC Research Press    

年代:1983

数据来源: NRC