同时考虑结构性和初始应力影响的双参量土体本构模型

AN ELASTO-PLASTIC MODEL SYNCHRONOUSLY CONSIDERING STRUCTURE CHARACTERS AND ORIGINAL STRESS FOR CLAY SOILS

原状土的结构性和初始应力状态对土的力学效应影响比较显著,在应力水平较小的情况下,原状土的力学行为与重塑土有很大的差异。目前,在描述土体应力应变的本构模型中,绝大多数模型都是基于重塑土在实验的基础上构建的,没有充分考虑土的结构性和初始应力状态的影响。本文在经典的弹塑性理论的大框架下,以桂林岩溶区分布的饱和软黏土为研究对象,结合室内试验的成果,依据前人已建的模型,考虑了土的结构性和初始应力的影响,在充分发挥修正剑桥模型优点的基础上对其进行改进,构建了一种新的饱和软黏土的弹塑性本构模型,并对模型作了分析和比较,初步表明了模型的合理性和有效性,进一步的工程验证研究还在进行之中。该模型的构建可使桂林岩溶区分布的饱和软黏土的应力应变计算更加趋近于实际,并且,对于桂林岩溶区高速公路饱和软基填土过程中,控制加荷速率和控制分级荷载的大小具有重要的现实意义。

The mechanical characteristics of natural soils are significantly affected by their structure and original stress. As undisturbed soil and remolded soil possess different structural features, they demonstrate different me- chanical properties in the case of minor stress. At present, lots of structural models have been established by re- molded soil and experimental conditions without considering structure and original stress. Under the classical theo- ries of elasto-plastic, based on soft clay in Guilin areas, combine with test indoor, according to the former model, an elasto-plastic constitutive model has been established to synchronously consider the structural characters and the original stress state based on the Modified Cam Clay. The＇ comparison and analysis of various calculated results have shown the rationality and validity of the model. The applications of the model expressions make the strain result more correspond to the engineering practice. They have important significance for controlling not only rate of loading but also size of load grade during highway filled soil in Guilin areas.