摘要
垃圾土中的生化-渗流-应力耦合行为会显著影响垃圾堆体的变形。该文首先引入了与降解在变形方面等效的附加应力Pb,建立了垃圾土降解-骨架弱化本构模型,该模型能够较好地描述降解变形和降解对压缩性的影响。然后,完善了垃圾土生化-渗流-应力耦合模型并采用OpenGeoSys软件开展了二维垃圾边坡耦合行为数值仿真,分析了底物浓度、甲烷产量等生化降解物理量和气压、侧向变形、沉降等力学物理量的演化规律及相互作用,相比仅关注垃圾土一维变形的耦合数值仿真有显著进步。该文研究成果可作为土木工程研究生数值试验课程的典型教学案例。
[Objective]Landfilling is a primary disposal method for municipal solid waste(MSW).The deformation of MSW mass,including vertical settlement and lateral displacement,notably affects landfill safety and operation.Accurately predicting the deformation of waste mass is crucial in engineering practice.MSW contains a substantial amount of degradable organic matter within its solid skeleton,which decomposes into soluble small molecules,methane,carbon dioxide,hydrogen,and water.Thus,bio–hydro–mechanical coupling behaviors in waste play a critical role in its deformation.To analyze these coupling behaviors,this paper develops a constitutive model of MSW that accounts for degradation-induced skeleton weakening and enhances an existing bio–hydro–mechanical coupled model.A coupling simulation for MSW mass is then conducted.[Methods]pb,a variable dependent on the degree of degradation,was introduced into the compression curve equation to characterize the effects of degradation on the compression behavior of MSW.The physical significance of pb is that it represents an additional stress inducing the same deformation as the skeleton weakening caused by degradation.The constitutive MSW model was developed by integrating the compression equation with the shear-dilatancy rule of the Modified Cam Clay model.Furthermore,an existing bio–hydro–mechanical coupled model,originally limited to one-dimensional deformation analysis,was enhanced based on the proposed constitutive model.Then,a coupling simulation for MSW mass was conducted using the finite element method code OpenGeoSys on a two-dimensional MSW slope with a low-permeability intermediate layer.The evolution and interactions of degradation-related physical quantities,such as substrate concentrations and methane production,and mechanical parameters,including gas pressure,lateral deformation,and settlement,were analyzed.[Results]The findings of this study include the following:(1)The proposed constitutive model of MSW not only captures the dependence of degradation-induced deformation on the constitutive behavior of MSW but also reflects the influence of degradation degree on the instantaneous mechanical responses of MSW,providing a solid foundation for numerical simulations.(2)Numerical simulation results indicate that high gas pressure develops in the bottom layer of the slope owing to the impermeability of the lower boundary and the low-permeability intermediate layer that restricts the upward migration of landfill gas.Consequently,degradation and high gas pressure are the two primary factors governing the deformation mode of the MSW slope.(3)When deformation is mainly controlled by degradation,such as during the acid inhibition stage,contraction deformation occurs at the slope toe,while settlement occurs at the slope crest.As gas pressure increases in the bottom layer following the acid inhibition stage,lateral bulging deformation develops at the slope toe.(4)Comparatively,the horizontal displacement rate and deformation mode of the MSW slope closely align with those observed in actual landfill slopes under similar engineering conditions.[Conclusions]Overall,the proposed constitutive model effectively captures the influence of degradation on the mechanical behavior of MSW,while the coupling simulation accurately reflects the deformation patterns of actual MSW mass,highlighting the engineering significance.The findings of this study can also serve as a valuable teaching case for numerical simulation courses in civil engineering graduate programs.
作者
马鹏程
陈云敏
杨文东
MA Pengcheng;CHEN Yunmin;YANG Wendong(College of Pipeline and Civil Engineering,China University of Petroleum(East China),Qingdao 266580,China;Institute of Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China)
出处
《实验技术与管理》
北大核心
2025年第5期115-122,共8页
Experimental Technology and Management
基金
国家自然科学基金青年基金(52408411)
2023年山东省研究生专业学位优质案例库项目(SDYAL2023025)。
关键词
城市垃圾土
本构模型
生化-渗流-应力耦合
数值仿真
municipal solid waste
constitutive model
bio–hydro–mechanical coupling
numerical simulation
