Abstract
Three kind of marine clays with various plasticity and silica sand were mixed at different proportions, and specimens were prepared either by water sedimentation or by pre-consolidation. A series of undrained triaxial compression tests was performed on the specimens under various confining stresses. Thus, soil samples with wide grain size distribution, i.e. ranging from sand to clay, were formed and, based on the test results, a unified method to evaluate the friction angle of sand-clay mixtures was proposed. When the fines content is low, phase transformation point appeared before reaching failure during undrained shear. On the other hand, the phase transformation point disappeared when the fines content exceeded Fc=30% in the case that fines were constituted of plastic clayey soils while it appeared at any fines content in the case of non-plastic fines.
