Abstract:

Considering the effect of the intermediate principal stress rationally, the unified solution of shear strength for unsaturated soils in terms of two state stress variables is presented, which is based on the unified strength theory and shear strength for unsaturated soils in terms of two state stress variables. Good agreements can be found between the results of this study and some results reported in the literatures. The proposed unified solution of shear strength for unsaturated soils in terms of two state stress variables is validated. With different distributions of matric suction, the unified solutions of active and passive earth pressures for unsaturated soils are deduced, which can avoid the shortages of Rankine earth pressures. The effects of the intermediate principal stress and matric suction on earth pressures are discussed. It is shown that the active earth pressure decreases with increasing the unified strength theory parameter or matric suction, whereas the passive earth pressure inverses. The active and passive earth pressures do not change more quickly when matric suction decreases linearly in deepness than that is constant.

Key words: unsaturated soils, unified strength theory, shear strength, matric suction, earth pressure