Garga, Vinod K.,Khan, Md. Mahbubul A.2009-03-232009-03-2319931993Source: Dissertation Abstracts International, Volume: 55-08, Section: B, page: 3463.9780315896734http://hdl.handle.net/10393/6929http://dx.doi.org/10.20381/ruor-11530The purpose of this research was to study the strength-deformation behaviour of a weathered clay crust in the Ottawa region. This study includes an extensive experimental programme, covering both field and laboratory tests. The field testing methods used were the field vane, the dilatometer, the piezocone, and the self-boring pressuremeter. Triaxial shear and consolidation tests were conducted in the laboratory testing programme. Conventional triaxial tests, in both compression and extension, and non-conventional stress-path tests covering various stress-paths in the triaxial space, were performed in this study. Constant rate of strain, constant rate of load, controlled gradient, as well as the conventional oedometer tests were conducted in the consolidation testing programme. In order to perform the laboratory experiments, a computer-operated triaxial stress-path control system and an automated consolidation apparatus were developed. The software for the automation of the above apparatus was also developed in this research. A laboratory method for the evaluation of in situ K$\sb0$ for highly overconsolidated soil has been proposed. Such a method is necessary for the stress-path triaxial tests, where reconsolidation of the triaxial sample to in situ state of stress is required. A new method of interpretation of field vane (FV) test, for anisotropic soil, has also been developed. In this method, the original equation for the interpretation of FV has been reformulated which includes the strength anisotropy of the soil, non-uniform stress distribution around the FV, effect of rate of shearing and the disturbance due to vane insertion. From the analysis of the laboratory triaxial and consolidation tests, for various depths within the crust, a well defined yield envelope was obtained. This yield envelope can be used to estimate the elastic and plastic strains for any stress-path in the field. The test results obtained from various laboratory and field tests have been compared with two case studies from the same site, and demonstrate the importance of the consideration of the in situ stress state.380 p.Engineering, Civil.Thesis