Study on Dissipation of Excess Pore Water Pressure of Clay

Abstract

Dissipation of excess pore water pressure of saturation clay was discussed in the paper. Monotonic loading, unloading-reloading, and creep tests of one dimensional compression were performed to study the orderliness of dissipation of excess pore water pressure. In the drained consolidated tests, strain rate was changed step by step to check the effects of excess pore water pressure on effective axial stress. Creep tests were performed in different stage of loading and unloading procedure under different effective axial stress. In order to estimate the effects of excess pore water on effective axial stress more precisely, excess pore water pressure ratio was introduced. Test results show that: (1) excess pore water pressure changed gradually as strain rate changed abruptly, while excess pore water pressure ratio changed quickly; (2) excess pore water pressure maintained constant shortly after the change of strain rate during monotonic loading tests under small strain rate; (3) excess pore water pressure may be smaller than back pressure during unloading-reloading tests, in which, excess pore water pressure ratio is negative; (4) there neutral creep existed in unloading-creep-unloading procedure. Excess pore water pressure ratio equal to 0 and excess pore water pressure maintained a constant value equal to the back pressure in neutral creep.