Orientation of Deposition Planes and Shear Strength of Typical Clays from Pakistan

This study presents results of unconsolidated-undrained triaxial compression tests on two typical clays of different plasticities from Pakistan. Remolded soil specimens were prepared using a special assembly to explore possible effects of orientation of deposition planes, shear rate and plasticity on mechanical behavior of soils. A stronger soil behavior was observed for samples with deposition planes perpendicular to axial loading, and this interaction weakened as orientation of deposition planes gradually became parallel to the axial load. With increase in shearing rate, low-plastic soil sample showed larger increase in strength parameters relative to high-plastic soil. For vertical and inclined deposition planes, a splitting failure surface along deposition plane was observed, whereas for deposition planes normal to loading direction the samples bulged out with no apparent slip surface. It is anticipated that the results of this study can be useful for interpretation of mechanical behavior of soil profiles with different orientations of deposition planes, soil samplings and loading directions.