Pore water pressure characteristics of saturated intact loess under constant stress ratio stress paths

The undrained triaxial shear tests for K_0 consolidated saturated intact loess were carried out to study the pore water pressure characteristics under two types of constant stress ratio stress paths including axial loading-radial unloading and axial unloading-radial loading.It is found that: 1.the pore water pressure is positive and increases quickly at first and tends to slowly later under both types of stress paths;2.the stress path may significantly affect the pore water pressure characteristics,it increases with the increase of stress ratio under axial unloading-radial loading stress path but decreased with the increase of stress ratio under axial loading-radial unloading stress path;3.the pore water pressure of saturated intact loess is produced by both the spherical stress increment and deviator stress increment.The pore water pressure produced by the spherical stress increment is independent of the non-linear property of soil,but the pressure due to shear stress is linearly related to shear stress.