Experimental Study On Deformation Characteristics Of Saturated Soft Clay Under Three-dimensional Cyclic Stress State

The stress components acting on the subgrade soil,involving the cyclic variation of major,intermediate and minor principal stresses,and the amplitude of the minor principal stress can be neglected.In this paper,a series of undrained cyclic true triaxial tests of saturated clay have been carried out,considering the factors of cyclic shear stress ratio?CSR?,coefficient of cyclic intermediate principal stress (b_cyc) and over-consolidation ratio?OCR?.Emphasis is put on the effects of these factors on the characteristics of major and intermediate principal strains,and resilient modulus in the direction of major principal stress.The main results are as follows:?1?The variation of major and intermediate principal strains,and resilient modulus in the direction of major principal stress are significantly correlated with the coefficient of cyclic intermediate principal stress (b_cyc).It is an appropriate parameter to characterize the cyclic characteristics of soil in three-dimensional cyclic stress state.?2?Based on the shakedown theory,the concept of allowable cyclic stress ratio is put forward.The relationships of permanent major and intermediate principal strains,resilient modulus against CSR is discussed.The values of allowable cyclic stress ratio under different b_cyc are determined.It was found that the one-way cyclic shakedown behavior of saturated clay is related to bcyc but independent of OCR.?3?The empirical models are proposed to predict the long-term deformation of saturated soft clay under three-dimensional cyclic stress state.?4?The critical value of the coefficient of cyclic intermediate principal stress (b_cyc) is obtained by the variation of the principal strain in the study.?5?The relationship between CSR&intermediate principal stress on pore pressure,effective stress path,strain path and hysteresis loop are studied.