考虑干湿循环影响的压实黄土结构性本构关系

Structural constitutive relation of compacted loess considering the effect of drying and wetting cycles

为研究不同干湿循环条件下压实黄土的结构性本构关系,对不同干湿循环条件下压实黄土试样进行固结排水三轴剪切试验。结果表明:不同结构状态压实黄土的三轴剪切力学特性差异明显,表现出明显的结构性。在分析干湿循环作用下压实黄土三轴剪切应力-应变关系曲线的基础上,根据综合结构势理论定义了干湿循环三轴剪切结构性参数,并验证了其合理性;将该结构性参数进行变换并将其引入Duncan-Chang模型,建立了能够反映干湿循环影响的三轴剪切结构性本构关系。利用该结构性本构关系式计算得到的应力-应变值与试验值进行对比分析,其结果较为一致,验证了干湿循环压实黄土结构性本构关系的正确性和合理性。进一步利用结构性本构关系,对某黄土填方工程实例进行了数值计算初步分析,揭示出干湿循环对填方地基的变形影响较大。

A series of consolidated drained triaxial shear tests was carried out on compacted loess samples under different drying and wetting cycles to study the structural constitutive relationship considering the effect of drying and wetting cycles. The results indicated that the triaxial shear mechanical properties of compacted loess in different structural states were significantly different,which is indicative of obvious structural characteristics. Based on the analysis of the triaxial shear stress-strain relationship curves of compacted loess under different drying and wetting cycles, the triaxial shear structural parameters of drying and wetting cycles were defined according to the theory of comprehensive structural potential, and the rationality of the parameters was verified. The structural parameters were transformed and introduced into Duncan-Chang model to establish structural Duncan-Chang model which includes the effect of drying and wetting cycles. The comparison results showed that the calculated value of the constitutive model was basically consistent with the experimental value, which verified the rationality and applicability of the structural constitutive model. In accordance of the constitutive relation and parameters in this paper, taking a loess filling project as an example, the preliminary numerical analysis of which showed that the drying and wetting cycles had a great influence on the deformation of the filling foundation.