土体微观力学解析模型:进展及发展

Micromechanics-based analytical model for soils:review and development

基于土体的微观结构分析基础上而建立的本构模型,不仅可以反映土体的应力-应变关系,而且可以揭示土体变形和强度发展的微观机理。为此,总结了当前考虑土体微观结构的力学本构模拟方法,并分为三大类别:①考虑微观分布特征的宏观模型;②基于非连续数值计算法的微观土力学模型;③取代表性体积在微观颗粒接触面方向上进行积分的解析模型。文中分析总结了不同方法之间的优缺点,并指出就目前阶段而言,微观力学解析方法不仅可以很好地考虑土的微观结构及其变化,还可以比较容易地应用于工程实践。为此,结合笔者及其合作伙伴近年来在砂土及黏土静、动力本构模拟上的研究成果,重点介绍了这种解析模型的框架以及能取得的模拟效果。最后,展示了微观力学模型在黏土流变特性及粗细颗粒混合土力学特性模拟上的最新扩展。

Different approaches of mechanical modeling accounting for the microstructure of soils are used to develop stress-strain models for granular materials. Three typical approaches are classified： macro model with fabric tensor of microstructure, distinct element or particle flow method, and micro-plane or micro-contact analytical method. The review for the development of above approaches is first presented. Their advantages and deficiencies are discussed. It can be concluded that at the current stage, the micromeehanics-based analytical modeling method can well consider the microstructure of soils and be applied in engineering practice. Therefore, this approach is presented together with the researches done during last several years by author and his related research groups for modeling the behaviors of sand and clay. Some new developments of the modeling of strain-rate dependency of clay and mechanical behaviors of coarse-fine grain mixture are finally presented.