K_0固结结构性软黏土的本构模型

A constitutive model of K_0 consolided structured soft clays

本文在修正剑桥模型的基础上综合考虑了软黏土的各向异性、结构性及其演变和屈服面硬化规则中塑性剪切应变的影响,将传统模型发展为适用于K0固结结构性软黏土的本构模型。本文模型借鉴Collins等人提出的符合热力学耗散原理的本构模型,同时在描述土体结构性演变的过程中参考了Asaoka等人的次加载/超加载屈服面本构模型,并采用了具有明确物理意义的内变量。与传统的修正剑桥模型相比,增加了3个分别表征软黏土各向异性和结构性的参数(θn,R和R*)以及两个演化参数(m和a),而参数R和R*的初始值则可由结构性土的屈服应力比YSR和灵敏度St获得。本文选取了典型的浙江温州软黏土和Bothkennar软黏土,对比了三轴压缩的计算和试验结果,体现了本模型在结构性软黏土计算上相对于传统本构模型优越性。

A constitutive model of K0 consolided structured soft clays was developed based on the Modified Cam Clay model. The effects of anisotropy and destructuration of the natural soils as well as shear hardening rule were considered with the rotational yield surface. This model came from the thermo-mechanical constitutive model developed by Collins and then the methods that Asaoka established in the super/subloading yield surface model were used. Three parameters （θn, R and R^＊） and two evolution parameters （m and a） were added to the Modified Cam Clay model together with the initial structural values which were related to the yield stress ratio and the sensitivity of the soft clays. Significant improvements were demonstrated in the performance of the new model over the traditional constitutive models with experimental evidence from Wenzhou clay and Bothkennar clay.