考虑降解效应的城市固体废弃物非线性本构模型

基于城市固体废弃物(MSW)的降解及土力学特征,在应力降解模型、等向压缩特性和邓肯-张模型的理论基础上,建立了一个能够描述MSW应力和降解耦合作用的全量非线性本构模型。给出了不同应力状态下单元体体积和轴向变形随时间变化的数学表达,同时给出了所有参数的确定方法。采用该模型对不同龄期和不同围压条件下填埋场现场试样的三轴CD应力-应变曲线以及室内长期一维降解压缩试验进行了模拟。结果表明,模型概念合理、参数明确,能够较全面地描述不同降解龄期垃圾的本构关系,可用于分析填埋场的长期变形。

A nonlinear constitutive model for municipal solid waste considering effects of degradation

According to the degrading and soil mechanical characteristics of municipal solid waste (MSW), a nonlinear constitutive model of total strain theory to describe the coupled effects of stress and degradation is established, on the basis of the stress-degradation model and isotropic compression characteristics and Duncan-Chang model. The mathematical expressions for volume and axial deformation of unit body changes with time in different stress states are given; and then methods for determining all parameters are also provided. Verification is implemented by simulating the stress-strain curves of MSW samples obtained from landfill and a few long term one dimensional compression tests in laboratory. The results indicate that the concept of the model is reasonable; the selection of parameters is relatively clear and the model is able to describe the constitutive relations of MSW with different degradation ages in a more comprehensive way, which can be used for analyzing the long term deformation of landfills.