| With the continuous improvement of people's living standards,the production of Municipal Solid Waste(MSW)is increasing rapidly.Landfill disposal is the main method to solve the domestic waste.In order to prevent the migration of filtrate and exhaust gas from the landfill to the surrounding environment,a composite cushion system composed of geosynthetics and compacted clay is usually set at the bottom of the landfill.Due to inadequate understanding of the engineering properties of MSW and the shear properties of composite lining interface,landfill instability has occurred in many countries.In order to provide reasonable parameters for the construction and design of the landfill,this paper systematically studied the properties of MSW engineering and the shear characteristics of the composite lining interface,and established the four wedge model considering the effect of the garbage dam,and analyzed the stability of the landfill.The main contents of this paper are as follows:(1)In this paper,the waste soil in a landfill site of xiangtan shuangma landfill site was selected as the research object,and the composition,density and moisture content of municipal solid waste were analyzed.At the same time,the direct shear test of natural state and saturated state is carried out by using the homemade large direct shear apparatus.The study found that the composition of MSW was complex,and the density was less than that of ordinary soil,and the moisture content measured was less than that of fresh garbage,and the change was not very large.Before and after immersion,shear stress and displacement curve of MSW has not obvious changes,reshape the shear strength indexes of MSW is: c = 41.80 kPa,?= 28.39 °;Saturated remodeling of shear strength indexes of MSW is: c = 41.11 kPa,? = 27.12 °,indicates that water have little impact on shear strength characteristics of MSW,this is because the city life garbage in density in the small plastic and fiber material is given priority to,the strength of the MSW characteristics mainly depends on the material "reinforcement".(2)The mechanical properties of the composite lining interface of landfill were studied by using the large-scale horizontal interfacial shear test device developed by ourselves.The interaction between geosynthetics was considered.The study found that the interface of composite lining seepage control system,geomembrane/GCL interface friction angle minimum,geotextile / geomembrane interface of saturated water;because of the "lubricating" effect,angle decrease with different degrees of the interface friction,one of the biggest,GCL /geomembrane interface by reducing 30.98%,geomembrane / geotextile interface times,reduced by 29.66%.The interface of the cloth / geomembrane and the geomembrane /GCL interface are the potential instability interfaces of the landfill.(3)Considering the influence of the waste dam and the transfer of the same slope surface,the stability analysis model of the four wedge is set up to consider the effect of the garbage dam.The landfill is divided into five parts.The static equilibrium analysis and the balance equation are carried out for each wedge.The MATLAB software is used to solve the safety factor.Finally,the garbage dam and the compound are analyzed.The influence of lining interface strength parameters and different terrain parameters on the sliding movement of the weak lining of the composite lining along the bottom of the landfill is also discussed. |
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