Study On Municipal Solid Waste Strength Characteristic And Slope Stability Analysis Based On Duncan-chang Model

Recently sanitary landfill has been the main way to deal with Municipal Solid Waste(MSW) in china.With the growth of economy and the development of urbanization level, the scale of Landfill Site has become larger gradually, the storage capacity has become greater, the design requirements have become higher and higher. Owing to the lack understanding of strength characteristics about MSW, lots of slope failures in Landfill Site happened at home and abroad,which led to serious secondary pollution,and the surrounding environment and residents were suffered from disastrous consequences.This thesis tries to have the experimental study on the strength characteristics of MSW. Secondary development of ABAQUS about Duncan-Chang model is carried by UMAT interface,which is used in analysis of the slope in Landfill.The thesis considers the influence of decomposition of organic matter on strength characteristics of MSW,and MSW samples simulating the compositions of MSW from the NanChang city is decomposed for several days in bioreactor. The consolidation drained triaxial compression tests were conducted on decomposed soil samples. The test results show that: The constitutive relation of the tested MSW basically fits the Duncan -Chang nonlinear elastic model. With the increasing of ambient pressure,the tangent modulus increases. The eight parameters of Duncan -Chang model are obtained from the tests,which provides reference for numerical simulation of triaxial test MSW and analysis of the slope in Landfill.ABAQUS is a kind of powerful and satisfactory development software. Secondary development of ABAQUS about Duncan-Chang model was carried by UMAT interface in the thesis,which provides thinkings and methods of secondary development.the key problems are explained such as consolidation pressure determination, load-unload judgment and initial stress field ,which provides reference for similar model.The numerical verification shows: Calculated results of numerical simulation and test data are nearly uniformly,and the subroutine of Duncan-Chang model can be applied to practical engineering about MSW.The thesis has analysis of the homogeneous slope in Landfill based on secondary development of ABAQUS about Duncan-Chang model. The calculated results show that: Less lateral displacement happens in the upper front slope, while more lateral displacement happens in the lower front slope,and the lagest lateral strain reaches 7.76% . However,the terminal equilibrium method is based on static equilibrium,so the safety factor never considers the effect of deformation.The lager deformation may destory covering system.Therefore, lateral displacement of slope is indispensable during the process of analysis of the slope in Landfill.