摘要:

Geotechnical engineering embraces soil mechanics, rock mechanics, and engineering geology. In practice it employs a wide variety of techniques ranging from site mapping and characterization to advanced theoretical analysis and performance monitoring. This paper draws on the development of the Alberta oil sands as a case study to illustrate the breadth of application of geotechnical engineering in large-scale resource developments.A description of the resource base and common extractive procedures used in the Alberta oil sands is given. The geological setting and geotechnical characterization of the Athabasca deposit are summarized. Detailed discussions are presented on geotechnical contributions to surface mining and slope stability, waste handling and tailings dam construction, andin siturecovery processes. The substantial opportunities for geotechnical engineering to contribute to both safe and economical operations in the extractive industries are emphasized.Key words: oil sands, mining, slope stability, monitoring, dredging, shear strength, tailings dam, overburden, liquefaction, pore pressures, geotechnical engineering.

ISSN:0008-3674    

DOI:10.1139/t88-076

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Full-scale field testing for the bearing capacity and stability of inclined footings with anchors was carried out on a colluvial slope near the east portal of the Rogers Pass tunnel in British Columbia. The 35° natural slope was composed of granular material with an angle of shearing resistance. A series of small footings (area 1.14 m2) was loaded with anchor loads only and one large footing (area 2.66 m2) was loaded with both anchor and vertical loads up to 2100 kN. Bearing capacity coefficients were back calculated and compared with coefficients from bearing capacity theories. Elastic and deformation moduli were calculated from load–displacement curves during loading and unloading and creep rates were observed at intervals during the tests.Key words: inclined footings, instrumentation, bearing capacity factors, soil anchors, natural slopes, colluvial soils, soil creep, deformation modulus, elastic modulus.

ISSN:0008-3674    

DOI:10.1139/t88-077

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

A laboratory test program was undertaken to assess the effects of various ionic surfactants on the mechanical and hydric properties of a kaolinite. The tests showed that surfactants, particularly the cationic species, significantly modified the properties of the unsaturated clay (water absorption rate, absorbed water quantity, suction, swelling, etc.); however, the behaviour of the saturated soil was hardly changed. These results were correlated with measurements of the wettability characteristics of thin plates of consolidated clay. An original method, based on the concept of unit work of dewetting, was used to measure the solid – liquid – gas contact angle of the porous and rugose substrate. In the case of the kaolinite mixed with the cationic surfactant, the contact angle reaches 90° (instead of the 49° for the reference system), corresponding to a significant decrease in the soil suction. Such a decrease can explain the results obtained during infiltration and swelling tests.Key words: surfactants, wettability, unsaturated clays, suction.

ISSN:0008-3674    

DOI:10.1139/t88-078

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

By 1980, coal production and coal recovery at the Whitewood mine, Alberta, were unacceptably low as a result of poor groundwater and surface water control at the mine. A feasibility study conducted to determine the most cost-effective method to reduce groundwater inflows into the mine pit and reduce pore-water pressures in the mine walls concluded that a vertical well dewatering system, which would be located behind the highwall, was the most suitable. A finite difference computer model was constructed and successfully applied to design the dewatering system. The flexibility and ease of application of the model made it possible to determine the optimum number, production schedules, and locations of the dewatering wells, in conjunction with evolving mine plans. The implementation of the dewatering well program and improvements in surface water and in-pit drainage have resulted in increased coal recovery, a significant decrease in mine wall failures, and improved coal quality.Key words: dewatering, modelling, groundwater, open-pit mining, hydrogeology, pumping wells, optimization, monitoring, coal recovery.

ISSN:0008-3674    

DOI:10.1139/t88-079

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Fly ash and bottom ash obtained from coal-fired electric power generating stations can be used as alternatives to natural materials for the construction of structural fills. The engineering properties of coal ash pertinent to its use in structural fills are discussed. Four case studies of coal ash structural fills are presented. The performance of these fills was monitored during and after construction. These cases demonstrate that the physical behavior of fly ash is similar to that of silt and that it can be handled with similar methods. Groundwater monitoring data from existing fly ash fills are presented to show the impact that ash leachate migrating into the groundwater regime has on water quality. Results of long-term corrosion studies are presented to show that metals buried in ash, used in such structures as culverts, cable ducts, guard rails and streetlights, are not adversely affected. Ash leachate was found not to be detrimental to good-quality concrete structures.Key words: fly ash, fill, compaction, leachate, corrosion, concrete.

ISSN:0008-3674    

DOI:10.1139/t88-080

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The field observations made during a sloped excavation in a soft sensitive clay are presented. The test site is located in Saint-Hilaire, in a typical Champlain Sea clay deposit, of 30 m depth. The trench was 8 m deep and 60 × 60 m square and its slopes were at 45, 34, 27, and 18° to the horizontal. The induced pore pressures and total lateral stresses have been recorded with vibrating-wire instruments since the beginning of the excavation. The steepest, 45° slope completely failed 1 day after excavating and the 34° slope, 2 weeks after. The piezometer readings have shown that the groundwater regime was modified proportionally to the changes in total stresses; these modifications took place within a time period of 5 months, after which the heads became more or less constant. The total stress cells indicated significant rotation of the principal axes at the toe of the slopes. Stability analyses using the lowest vane strength profile gave minimum factors of safety of 1.15 for the 45° slope and 1.23 for the 34° slope, thereby underestimating the risks of failure. Back analyses using regional effective shear strength parameters were made and the parameters mobilized at failure were found to beand.Key words: case record, excavation, soft clay, slope stability, back analysis.

ISSN:0008-3674    

DOI:10.1139/t88-081

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The foundation material at the Ridgway Dam site is broadly classified as mudstone. The observed foundation settlements along the invert of the river outlet-works conduit at Ridgway Dam are on the order of 0.3 m. Numerical analyses were performed to estimate the deformation properties for a foundation material that under the existing embankment loads would deflect in a manner similar to the settlements surveyed along the invert of the outlet-works conduit. The foundation deformation properties determined from these analyses are compared with those obtained through the laboratory testing of the site-specific foundation materials and the published data. The results of the analyses, the field instrumentation data, the site geology, and the laboratory data provided an input to the decision-making process for the rehabilitation of the river outlet- works conduit.Key words: foundations, settlements, embankment dams, mudstones, analysis.

ISSN:0008-3674    

DOI:10.1139/t88-082

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Ice cover movements and stresses were measured near Adams Island from November 1984 to May 1985. The average horizontal movement rate was 0.1 m/day. Global compressive and tensile strains were less than 1 and 4%, respectively. Strain rates (measured over 1 – 2 month periods) were of the order of 10−9 s−1. Maximum stresses and forces in the ice cover were 500 kPa and 400 kN/m, respectively.Key words: ice movements, ice stresses, ice forces, Canadian Arctic Ocean.

ISSN:0008-3674    

DOI:10.1139/t88-083

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

This paper explores the feasibility of using optimization methods to search for the minimum factor of safety in slope stability analysis. The routine procedure includes comparing a number of admissible surfaces that are basically selected by random searches. Low efficiency and unreliability are the problems commonly encountered.Optimization methods allow a mathematically rigorous and reliable search for the minimum factor of safety and its associated "critical slip surfaces." This paper employs simplex, steepest descent, and Davidon – Fletcher – Powell (DFP) methods. The results of a number of test problems, in conjunction with closed-form and grid search solutions, showed that all the above-mentioned methods can provide reasonable results. Case history analyses supported the feasibility of the methods. Modifications to the DFP method were found to be essential for successful implementation of the minimization procedure.Key words: slope stability, landslide, analysis, limit equilibrium, interslice forces, factor of safety, spline function, optimization methods, case history.

ISSN:0008-3674    

DOI:10.1139/t88-084

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

For parts of the western Canadian plains, high-altitude airphotos and satellite images frequently show a simple pattern of preferred fracture lineament orientations. Fracture lineaments are composite linear topographic, drainage, vegetation, moisture, and tonal features. A long search for their origin and repeating characteristics is described. It is held that certain elements of fracture lineament networks are selectively inherited from preexisting regional fracture systems and structures in the underlying rocks, and can therefore be correlated with subsurface geological, hydrogeological, and geophysical and near-surface geochemical data. A number of case studies illustrate how remotely sensed lineament data are applied in geological, hydrogeological, and geotechnical investigations for resource exploration, development, and management.Key words: remote sensing, fracture lineaments, propagation, hierarchy, domain, stress field, salt tectonics, data correlation, application.

ISSN:0008-3674    

DOI:10.1139/t88-085

出版商:NRC Research Press    

年代:1988

数据来源: NRC