Experimental study on time-dependent behavior of silty mudstone from the Three Gorges Reservoir Area, China

Short-term and creep tests were performed on saturated silty mudstone obtained from the Three Gorges Reservoir area. Based on the triaxial creep test results, the variations of creep strain and creep rate of silty mudstone with time were analyzed in detail, and the differences between the axial and lateral creep parameters were quantitatively studied at different deviatoric stress levels. The longterm strength of silty mudstone was obtained. The results demonstrate that the lateral creep characteristics are more significant than the axial creep characteristics for silty mudstone in the tests. Analysis of the lateral creep characteristics of the rock is a reasonable approach to determine whether creep failure occurs in the silty mudstone. The long-term strength of silty mudstone decreases remarkably, and it is actually the lateral long-term strength of the rock. According to the triaxial creep curves of silty mudstone, a new nonlinear viscoelasto-plastic creep model was proposed by connecting in series the nonlinear viscoplastic body with the sixcomponent model. Comparing the model curves with test results, this model was determined to reflect the creep properties of silty mudstone accurately. Finally, the selection of the creep model parameters was achieved by considering the axial and lateral creep characteristics of silty mudstone.