非饱和土抗剪强度的非线性分析

Study on Nonlinearity of Shear Strength of Unsaturated Soils

针对非饱和土体的总粘聚力与基质吸力之间的非线性关系进行了研究,提出了具有非线性系数的总粘聚力与基质吸力的非线性关系式,并进一步得到了相应的非饱和土抗剪强度公式.通过采用四种不同性质土体的试验数据的检验与分析,证明了关系式的可行性与实用性.研究表明:非线性系数是与土的性质有关的重要参数,对于特定的土体,其值可以不随基质吸力的变化而变化,而取为常数,可以通过选取不同的非线性系数值来反映不同类型土的非线性特征;当非线性系数的值为1时,含有非线性系数的抗剪强度公式与已有Fred lund非饱和土抗剪强度公式的形式相同,说明Fredlund非饱和土抗剪强度公式只是关系式的一种特殊情况,含有非线性系数的抗剪强度公式有着更广泛的适用性.

The purpose of this paper is to research the nonlinear relationship between total cohesion and matrix suction. A nonlinear equation to indicate the nonlinear relationship is established with a nonlinear coefficient, and a new shear strength equation for unsaturated soils is derived. Utilizing the test data of four different unsaturated soils, the reliability and practicability of the two equations are verified. The results show that the nonlinear coefficient is also an important parameter for the unsaturated soils, which is a constant and does not vary with matrix suction. Different soils may take different values of nonlinear coefficient. When the value of the nonlinear coefficient is equal to one, the shear strength equation with the nonlinear coefficient exhibits a smooth transition towards the shear strength equation for unsaturated soils proposed Fredlund, which is a special form of the new shear strength equation for unsaturated soils in this paper.