Experimental Research on Mechanical Properties of Silty Clay Under Broken Line Stress Path Condition
To explore deformation law,pore pressure variation,and strength index of the silty clay under the special stress path condition of foundation pit excavation first and large tonnage hoisting at foundation pit side then,taking silty clay undisturbed soil samples near a tunnel in Jinan city as research objects,K0 consolidation undrained shear test with lateral unloading followed by axial loading was adopted and three different unloading ratios were selected during the unloading stage to simulate the stress path under a special condition of foundation pit excavation first and large tonnage hoisting at foundation pit side then.Isobaric consolidated undrained conventional triaxial shear test and K0 consolidated lateral unloading undrained shear test were then carried out,and the three experimental results were compared.The results show that deviatoric stress-axial strain test curves under the special stress path condition of foundation pit excavation first and large tonnage hoisting at foundation pit side then are nonlinear curves.The failure strength of silty clay is related to the unloading amount.The greater the unloading amount is,the smaller the failure strength is.Negative pore pressure is generated in reducing confining pressure stage.Pore pressure first increases and then decreases with the increase of axial strain in axial applying pressure stage.Under the same initial consolidation confining pressure,the small the unloading ratio of silty clay is,the greater the maximum pore pressure generated in shear is.Under the special stress path condition of foundation pit excavation first and large tonnage hoisting at foundation pit side then,the greater the unloading ratio of silty clay is,the greater the effective cohesion is and the smaller the effective internal friction angle is.Compared with the isobaric consolidated undrained conventional triaxial shear test,the effective internal friction angle is smaller,and the effective cohesion is larger or smaller according to different unloading ratios.
NETL
NSTL
万方数据
维普
