Assessment of Shear Strength Parameters of Marine Dredge Sand

Cohesion and friction angle represents the shear strength parameters of soils. Linear Mohr–Coulomb envelope is the widely used theoretical concept to describe the shear strength of the soils which are related to the geotechnical analysis and designs. However, sand deviates considerably from linear Mohr–Coulomb envelope due to the effects of factors such as confining pressure, relative density, mineralogy, particle crushing, particle size distribution and fines content. The Colombo port city development project, which is in coastal region, reclaimed dredge sand over 13 m depth. This project was proposed to include low rise and high rise buildings all over the reclaimed land where the type of foundation may vary depending upon the structural loads and subsurface conditions. Therefore, determination of shear strength parameters for different loading condition is of utmost importance to determine the bearing capacity and to select the dimensions of foundations. In this study, basic engineering properties of reclaimed sand collected from Colombo port city project were examined. A series of laboratory direct shear tests were conducted to determine the variation of shear stress over different normal stresses. From the analysis of experimental data, it was revealed that shear stress of dredged sand varies linearly with normal stress up to 100 kPa and showed nonlinear behavior thereafter.