不同应力路径下黏性土的力学特性研究

Study on Mechanical Properties of Clayey Soil under Different Stress Paths

对上海地区⑤1层软黏土进行了常规三轴、减压三轴试验,以研究考虑不同应力路径的力学特性。分析了初始固结状态对软黏土应力路径的影响,比较了不同应力路径下土体的应力-应变关系特征和孔隙水压力变化规律,计算了土体抗剪强度指标。研究结果表明,应力路径对土的峰值强度、孔压、有效应力路径等特性影响很大,软粘土的应力-应变关系具明显的非线性,且基本呈应变硬化型;常规三轴试验中孔隙水压力为正值,减压三轴试验中总体为负值;初始固结状态对黏土的抗剪强度有一定的影响,且影响主要来自对黏聚力值上,对内摩擦角值影响较小。

In order to study the mechanical properties considering the different stress paths,the conventional triaxial and decompression triaxial tests are carried out for the soft clay of⑤1 layer in the area of Shanghai.The influence of initial solidification state on the stress path of soft clay is analyzed.The characteristics of stress-strain relationship and the variation laws of pore water pressure of the soil mass under the different stress paths are compared.The shear strength index of soil mass is calculated.The results show that the stress path has a great influence on the peak strength,pore pressure and effective stress path of soil.The stress-strain relationship of soft clay is obviously nonlinear and basically strain hardened.The pore water pressure is positive in conventional triaxial test and negative in decompression triaxial test.The initial solidification state has a certain influence on the shear strength of clay,and the influence mainly comes from the cohesion value,which has little influence on the internal friction angle value.