考虑纤维加筋作用的城市生活垃圾土弹塑性本构模型

Elastoplastic constitutive model for municipal solid waste considering the effect of fibrous reinforcement

城市生活垃圾土的成分非常复杂,大量纤维材料(如塑料、纺织物、皮革等)的存在使得其力学性质与普通土体之间存在明显差异。现有土体本构模型难以对垃圾土的力学行为进行较好的模拟。对此将垃圾土看作是由纤维材料和泥状物(除纤维材料外剩余的成分)组成的复合体,荷载作用下垃圾土的力学特性取决于纤维材料和泥状物的共同作用,并提出了纤维作用参数R的概念。通过构建新的反映纤维加筋作用的塑性势函数,并依据试验结果推导了纤维作用参数R的演化方程,建立了一个能够合理描述垃圾土力学应力-应变特性的弹塑性本构模型。将垃圾土本构模型的计算结果与三轴排水试验结果和他人模型结果进行比较,发现该模型能较好地反映垃圾土应力-应变特性,尤其是应变水平较大时应力-应变曲线上翘的形状,验证了该模型的合理性和有效性。该模型的建立可为更好地服务于垃圾填埋工程提供理论依据。

The composition of municipal solid waste(MSW) is very complex. A lot of fibrous materials in MSW, such as plastic,textile, leather and so on, make the mechanical properties of MSW obviously different from common clay and sand soil. It is difficult to simulate the mechanical behavior of MSW by the existed soil constitutive models. In this paper, the MSW is regarded as a combination composed of fibrous materials and paste, where paste is the residual components except for fibrous materials. The mechanical properties of MSW under the external load depend on the combined action of fibrous materials and paste. A concept of fibrous reinforcement effect parameter R is proposed in this paper. Through the development of plastic potential function considering the fibrous reinforcement, a new elasto-plastic constitutive model is established to simulate the stress-strain characteristics of MSW reasonably. The evolutionary equation of fibrous reinforcement effect parameter R is derived based on the test results. By comparing with the results of triaxial drained test and calculations of other constitutive models, it is found that the proposed model can perfectly reflect the stress-strain responses of MSW, especially for the upward curvature of MSW stress-strain responses at a larger strains level.As a result, the reasonability and effectiveness of this MSW constitutive model have been verified. The development of MSW constitutive model presents an important theoretical basis for better servicing landfill engineering projects.