特殊应力路径下软黏土变形与强度特性试验研究

Test research on deformation and strength properties of soft clay under special stress path

通过进行软黏土的常规三轴固结排水试验、K0固结轴向加载排水剪切试验及K0固结侧向卸荷排水剪切试验,模拟基坑侧壁土体的实际应力路径,对比分析3种不同应力路径下土体的变形和强度特性。分析结果表明:①在3种试验应力路径下,软黏土土样破坏时的主应力差值随着固结围压的增加而增加,均呈近似线性变化;②侧向卸荷应力路径下,软黏土的变形和强度特性较之常规三轴试验结果均有较大差异;③相对于各向等压固结,K0固结条件下土体的凝聚力减小,内摩擦角增大。研究结论为基坑设计时采用反映土体实际应力路径的力学参数提供了理论依据。

By conducting the conventional triaxial drained shear test, K0 consolidation axial loading shear test and K0 consolida- tion lateral unloading drained shear test, we simulate the real stress paths of soil body at lateral parts of foundation pit and analyze the deformation and strength properties of the soil under the above three different stress paths. The results show that ： under the 3 testing stress paths, the principle stress differences of the failure of soft clay increase with consolidation confining pressure linear- ly; the deformation and strength properties of soft clay under lateral unloading stress path are distinct with conventional triaxial drained shear test ; compared with condition of consolidation isotropically drained shear test, cohesion is reduced and angle of in- terngl friction increases under Ko consolidation condition. The results have theoretical meanings for foundation pit design, and the soil parameters that can reflect real stress path of soil body are suggested.