Influence Mechanism Of Waste Leachate On The Interface Shear Characteristics Of The GCL Composite Liner

The composite impermeable liner composed of HDPE geomembrane(GM)and geocomposite bentonite liner(GCL)is widely used in the impermeable structure of landfills.The shear strength of GM+GCL composite liner is the main controlling factor of the overall slip stability of landfills.The chemical leachate generated by the degradation of waste bodies in landfills and the high temperature environment can affect the shear strength of the composite liner,which becomes This becomes an uncertainty factor for landfill slip stability.In order to reveal the mechanism of the influence of leachate on the shear strength of GM+GCL composite liner,this paper conducts large-size constant temperature shear test of GM+GCL composite liner under composite leachate hydration and compares and analyzes the shear characteristics under different temperature and pressure under leachate hydration and general hydration conditions,respectively.The main research contents of this paper are as follows:(1)Summarize the leachate data from different regions of China in the literature,summarize the characteristics of chemical components of landfill leachate in China in terms of ion species,concentration interval,ionic strength(I)and relative ion abundance(RMD),and propose a typical representative formulation scheme for composite leachate from landfills in China.(2)Carry out large-size water bath shear tests of GM+GCL composite liners under different normal pressures under composite leachate hydration conditions.Revealing the shear damage patterns and strength characteristics of GM+GCL composite liners under different normal pressures of leachate hydration.Comparative analysis of shear properties and differences in results of GM+GCL composite liners under two conditions of general hydration and leachate hydration with GCL respectively.(3)Further large-size water bath shear tests of GM+GCL composite liner under leachate hydration conditions at different temperatures.Revealing the shear damage mode,strength characteristics and extrusion of bentonite inside GCL for GM+GCL composite lining under the combined effect of composite leachate and temperature.A linear model was used to fit the shear strength test results to establish the quantitative relationship between the shear strength of leachate hydration composite liner and temperature and normal pressure.