黏土的张拉-剪切耦合强度研究

现有的土体强度研究主要集中在土体受到压缩剪切作用，而针对单轴拉伸、拉剪耦合或多向拉伸作用的研究较少。当前土的联合强度理论仍建立在土体受压缩剪切作用的基础上，不适用于分析土的抗拉强度和拉剪耦合强度。针对饱和黏土中的拉剪联合作用，建立了饱和黏土的张拉-剪切耦合强度模型，给出了饱和黏土张拉-剪切耦合强度公式以及多向拉伸作用下的强度公式；基于已有的饱和黏土试验数据以及所做的饱和黏土室内试验数据对所建立的强度模型预测能力进行了验证，并与其他联合强度模型进行对比分析，检验了强度模型的适用性和准确性；强度模型全面、合理地描述了饱和黏土的压剪强度、张拉-剪切耦合强度及多向拉伸强度特征，为饱和黏土张拉-剪切耦合问题的解决奠定了理论基础。

Study on tenso-shear coupling strength of clays

Traditional studies on soil strength are mainly concerned with the soils subjected to the compressive shear stress state, and only a few addressed the strength characteristics of soils subjected to uniaxial tension, triaxial tension or combinations of tenso-shear. Based on the analysis of the existing results, a tenso-shear coupling strength model is developed with considering various combinations of tenso-shear in saturated clay. The failure envelope and the peak strength line as well as the strength under multidirectional tension are analyzed, and the corresponding strength formulations with specific derivation process are obtained. Different types of saturated clay are selected for the uniaxial tensile test, direct shear test and triaxial shear test. It is shown that the proposed model performs very well. Due to the complete theoretical basis and simpler strength formulation, the proposed strength model can be conveniently applied in practice, yielding better results in understanding and analyzing the behavior of saturated soils subjected to combinations of tenso-shear, such as slope instability caused by rainfall infiltration or earthquake loading.