非饱和土平均粒间应力的计算及应用

土体各相之间物理化学作用对环境及能源等岩土工程都有重要影响，有效应力原理是解决上述问题最重要的理论。而目前的有效应力表达式无法描述由于物理化学作用引起的土颗粒间接触应力的变化。针对上述问题，最近提出了一个平均粒间应力表达式可以表述非饱和土内部的物理化学作用。为了实现该平均粒间应力的定量化计算并验证其稳定性和有效性，首先阐述了平均粒间应力表达式中各部分的物理意义。通过参数分析，得到了平均粒间应力各部分随含水率和孔隙盐溶液浓度的变化规律。推导出了表面力势中表征固液界面相互作用部分的计算公式，实现了平均粒间应力的定量计算。计算了临界状态时的非饱和土平均粒间应力，并应用平均粒间应力对非饱和土化学力学加载试验进行模拟。结果表明，临界状态时平均粒间应力与剪切强度具有唯一关系，应用平均粒间应力的计算结果与试验结果符合较好，验证了平均粒间应力公式的稳定性和有效性。

Calculation of mean intergranular stress and its application in unsaturated soil

The physicochemical interactions between different phases of the soil have an important impact on the geotechnical engineering related to environment and energy. The principle of effective stress is always the most important and effective theory to solve the relevant problems. However, the change of inter-particle stress caused by physicochemical effects cannot be accurately described by current effective stress equation. In response to the above problems, a mean intergranular stress expression that uniformly describe capillary, adsorption and osmosis effects between soil particles has recently been proposed. The purpose of this research is to realize the quantitative calculation of the mean intergranular stress and verify its stability and effectiveness. Firstly, the physical meaning of each part in the expression of mean intergranular stress is analyzed. Through analyzing the parameter in the expression, the variation rule of each part of mean intergranular stress with the water content and the concentration of pore water are obtained. Then, the formula characterizing the solid-liquid interface interaction for the surface force potential is derived, which can be used for the quantitative calculation of the mean intergranular stress equation. Finally, the mean intergranular stress of unsaturated soil in the critical state is calculated, and applied to simulate the coupled chemical-mechanical loading test of unsaturated soil. The calculated results show that there is a unique relationship between mean intergranular stress and shear strength in the critical state, and the chemical-mechanical calculation results give good agreement with the experimental results, verifying the stability and effectiveness of the mean intergranular stress.