基于非线性强度准则的城市固废本构模型

A constitutive model for the municipal solid waste based on nonlinear strength criterion

摘要:

考虑到城市固体废弃物剪切强度常具有非线性的特点，在三轴应力空间建立了基于幂函数形式的强度准则。并据此分析了该准则转换为线性Mohr-Coulomb准则时摩擦角的变化规律，结果表明，该准则能合理反映内摩擦角随围压增大而降低的特性。基于幂函数强度准则，采用增量硬化准则建立屈服函数，并通过构建合理的塑性势函数，建立了一个非相关联流动法则的固废弹塑性本构模型。通过对固废三轴固结排水试验结果模拟表明，所建立的本构模型不仅能合理模拟应力应变关系，亦能正确反映其体变特性。

关键词:城市固废;非线性强度;弹塑性;本构模型

Abstract:

Considering the nonlinear characteristic of the shear strength of the municipal solid waste and based on power form function, a nonlinear strength criterion in p-q stress space was proposed. According to the proposed criterion, the friction angle corresponding to the linear Mohr-Coulomb criterion was obtained, and it was shown to decrease with the increasing of the initial confining stress. By adopting the incremental hardening rule and suitable plastic potential function, a non-associated elasto-plasticity model for the MSW was built. By predicting a series of consolidated drained triaxial tests of MSW, the proposed model was shown to be able to predict the stress-strain relationships of MSW rightly and could give out reasonable prediction of the volumetric strain.

Key words:municipal solid waste; nonlinear shear strength; elasto-plasticity; constitutive model