UH模型在有限元分析中的应用

由姚仰平等提出的超固结土统一硬化模型(UH模型)能够描述超固结土的硬化、软化、剪缩和剪胀等应力应变特性以及应力路径对它的影响。通过改进,直线型的Hvorslev线由抛物线型的Hvorslev线代替,UH模型的参数与剑桥模型(Cam-clay模型)的参数相同。应用该模型,对三轴试验进行有限元模拟,分析了与应用Cam-clay模型所得应力应变关系曲线的异同点;针对刚性承压板试验,进行了地基承载力的三维有限元分析,比较了与应用Cam-clay模型和摩尔库仑模型(Mohr-Coulomb模型)等所得p-s曲线的不同,分析了地基中不同点处的应力-应变关系曲线,并与Boussinesq弹性理论计算的应力做了比较;进行了地基固结沉降数值分析,比较了孔压、沉降的变化规律,体现了UH模型的优越性。

Application of UH model to finite element analysis

The over-consolidated unified hardening model (UH model) proposed by Yao et al can describe many characteristics of clays well, including stress-strain relationships, stress dilatancy, strain hardening and softening, and path dependency behavior. Linear Hvorslev envelope has been substituted by a parabola Hvorslev. The parameters in the model are the same as those in the Cam-clay model. By using the UH model, numerical simulation of triaxial tests is performed. The difference of stress-strain curves predicted by using the Cam-clay model and the UH model is analyzed. To the test on rigid bearing plate, three-dimensional finite element analysis of foundation bearing capacity is carried out. The curves p-s are compared using the UH, the Cam-clay and the Mohr-Coulomb models. Stress-strain curves calculated by using the UH model in soil are analyzed. The stresses calculated by using the UH model and Boussinesq elastic theory solution are compared. In addition, numerical analysis of consolidation settlement is performed. The changes of pore pressure and settlement are analyzed and compared. It is shown that the UH model is better than the Cam-clay and Mohr-Coulomb models; and it is easy to be applied to the FEM from the comparisons of various calculation results in this paper.