不同应力路径下上海软黏土三轴不排水剪切孔压的对比

Pore pressures of Shanghai soft clay under undrained triaxial loading with different stress paths

软黏土不排水剪切过程中的孔隙水压力分析是软土工程的一个重要研究方向。三轴试验是研究软黏土不排水剪切孔压及孔压系数的传统方法,而孔压以及孔压系数的大小与应力路径以及剪应变的大小有关。利用GDS应力路径三轴仪,对上海软黏土原状土样与重塑土样进行了三轴ICUC(等压固结压缩剪切),三轴ACUC(K0固结压缩剪切)和三轴ACUE(K0固结拉伸剪切)三种应力路径的不排水剪切试验,对比这三种试验的剪切孔压及孔压系数的大小及变化规律,给出结构性以及各向异性对剪切孔压的影响规律。最后根据试验结果给出了上海软黏土在变形较大情况下的剪切孔压—应变双曲线模型的参数,可供设计计算采用。

Analysis of pore pressure under undrained loading is an important issue in soft clay engineering.Triaxial testing is a traditional method used in studying the pore pressure of soft clays under undrained loading.However,pore pressure and its coefficients are related to the stress path and shear strain.Three triaxial undrained shear tests,isotropic consolidated undrained compression shear,K0 consolidated undrained compression shear,and K0 consolidated undrained extension shear were performed on both undisturbed and remolded Shanghai soft clays using triaxial stress path apparatus(GDS Instruments).The variations in pore pressure and pore pressure coefficients in the three tests are presented and compared.The influences of soil structure and anisotropy on the pore pressure of soft clay are discussed.Based on the test results,the parameter values of the hyperbolic model for the pore pressure-strain relationship of Shanghai soft clay are provided.This information will be valuable for engineering practices under large shear strain conditions.