基于均匀化理论的土石混合体应力应变关系

将土石混合体等效为理想的二元介质混合材料，假定块石元为理想的脆弹性材料，土体元为典型的弹塑性材料。选取邓肯-张模型定义土体的本构关系，引入块石元局部应变系数建立土石混合体代表单元体积平均应变与其中块石元、土体元微应变的桥联关系。通过均匀化理论对土石混合体代表单元的一般应力应变关系进行了详细探讨。选取广东省云罗高速高填路基土石混填料中的残积粉质粘土，通过室内常规三轴压缩实验对土体邓肯-张模型的参数进行标定，描绘出不同围压及不同含石率条件下土石混合料一般应力应变关系曲线图。结果表明,均匀化理论得到的函数关系式能够较好地反映土石混合体在不同条件下的一般应力应变关系。随着土石混合体含石率的提高其抗剪能力显著增加，但当含石率小于0.3时，块石元的增强效应并不明显。

Stress-strain relationship of soil-rock mixture based on homogenization theory

Soil-Rock Mixture (SRM) is a kind of discontinuous and heterogeneous geotechnical material, and its mechanical property has become a subject of debate in geotechnical engineering. In the present study, SRM was assumed to be an ideal binary medium material, in which the rock and soil were assumed to be brittle-elastic and elastic-plastic media respectively. Duncan-Chang model was employed to define the constitutive relationship of soils. A new parameter named local strain coefficient of rock was adopted to relate the microscopic strain of the media and the volume average strain of SRM. The stress-strain relationship of SRM was then obtained by the simple homogenization theory. A series of tri-axial tests were conducted for the residual soil from Guangdong Province to obtain the coefficients in stress-strain function. The final relation curve could reflect the stress-strain relationship of SRM preferably under different conditions. The results show that the shear strength of SRM increases relatively with the increasing of confining pressure and volume rock rate of SRM. However, the strengthening effect by rock is not obvious when the volume rock rate is less than 0.3.