不同加载路径下饱和砂土的静力液化失稳试验研究OA

[Purposes]To investigate how loading path affects the static liquefaction responses of the saturated sand.[Methods]The static liquefaction responses of saturated loose sand were investi-gated by performing the triaxial tests involving varied loading paths.[Results]The test results show that the saturated loose sand liquefies with different confining stresses when subjected to undrained tri-axial compression loading path.The presence of initial shear prior to the undrained triaxial compres-sion accelerates the onset of static liquefaction related instability.The suppressed contraction occurs in the saturated loose sand sample when constant deviator stress is imposed in the undrained condition,which leads to a slow build-up of the excess pore water pressure and spontaneous liquefaction.The un-drained loading is not a necessity to trigger the static liquefaction related instability.Under the drained condition,static liquefaction related instability arises in the saturated loose sample when subjected to the loading path involving the increase of the deviator stress as well as the drop of the effective radial stress with a rate of-0.5 kPa/s.The effective stress ratio(q/p′)of the saturated loose sand under the varied loading paths is approximately 0.74,and the corresponding internal friction angle is 19.2°.The flow liquefaction line(FLL)is not an inherent property of the sand with the absence of physical signifi-cance.Whether the instability initiates or not when the effective stress path of saturated loose sand ap-proaches the FLL is largely controlled by the loading path.With a certain loading path,the static lique-faction related instability may be triggered once δp′/δσ′3=1 is attained,and to achieve this it should be ensured that loading path before the initiation of instability has not significantly affected the void ratios of samples.