INFLUENCE OF PRE-EXISTING FAILURE PLANES ON CLAY SHEAR STRENGTH: A SLIDING BLOCK METHOD ANALYSIS

This thesis investigates the shearing behaviour of Speswhite Kaolin through triaxial testing under both saturated drained and undrained conditions, analyzing homogeneous specimens as well as those with pre-existing failure planes. The primary objective of the study was to evaluate the shearing response of the material under varying stress states and to determine if extended shearing tests up to 30% axial strains could reveal the material's residual condition. A novel analytical approach, the Sliding Block Method (SBM), was developed and compared against conventional methods to analyze the shearing stage behaviour more effectively. This innovative method is designed to provide a more accurate representation of stress states. The force equilibrium on the soil body is evaluated considering the actual forces acting on the external surfaces of the specimen during the shearing stage and incorporating a comprehensive area correction of the failure surfaces developed in the sample.Significant findings from this study indicate that the SBM enhances the interpretation of triaxial test data, especially by considering the friction between the specimen's top surface and the porous stone. In contrast to conventional methods, which often overlook such interactions, the SBM allows for a more detailed understanding of shearing process, particularly in the post-peak and post-sliding phases of testing.This thesis demonstrates that the SBM offers a realistic approach to interpreting shearing behaviour data, potentially applicable to other triaxial shearing tests. This method is beneficial for geotechnical engineering applications, providing deeper insights into the material's behaviour under stress. The integration of friction considerations into the SBM significantly refines the analysis, leading to more accurate predictions and a richer understanding compared to conventional methodologies.