Study On Stability Of Stratified Landfill Under The Influence Of Age

The landfill has outstanding highly heterogeneous characteristics,and its physical and mechanical parameters will change with time and space,showing significant variability,which is related to the safety and economic problems of the landfill.Therefore,it is necessary to study the stability of landfill under the influence of age.On the basis of reading a large amount of literature,the research progress related to the subject was grasped,and the effects of age changes in several landfills were statistically collated and analyzed,and the changes in shear strength parameters and components were analyzed regularly and compared with the changes in a landfill in Jiangsu.On this basis,considering the layered contribution of high-density polyethylene(HDPE)geomembrane and combined with the conventional slope stability analysis method,the stability of layered landfill is analyzed.Combined with the analysis results,the following main conclusions are obtained:(1)The percentage of components changes significantly with the increase of landfill age,which in turn affects the changes of shear strength parameters of the landfill body.With the increase of landfill age,the cohesive force shows a decreasing trend of quadratic function and the internal friction angle shows a growing trend of logarithmic function.(2)The analysis of landfill body slip shows that the horizontal displacement of the landfill slope body is mostly concentrated in the vicinity of the slope body proximal surface,and its horizontal displacement value shows an increasing trend towards the middle of the side slope;in the vertical displacement of the landfill slope body,the settlement is concentrated in the top position of the landfill body,while the upward uplift is mainly concentrated in the side slope,and the overall slip form of the landfill body is manifested as a multi-layered extended pushed landslide.During the increase of the age of landfill from 11 to 20 years,the maximum displacement of the landfill body decreases by about24%,and the absolute value of displacement at the bottom of the landfill body decreases by about 12%.The effective stresses in both horizontal and vertical directions of the landfill slope show a trend of gradual increase along the depth direction,and there is a concentrated distribution of shear stress in the foot of the landfill slope and nearby areas.(3)Through soil-membrane tests,it was found that the cohesive force at the soil-membrane interface has an overall decreasing trend and the internal friction angle at the interface has an overall increasing trend in waste soils of different landfill ages.Due to the difference of geomembrane roughness,column point HDPE geomembrane has higher interfacial shear strength.Through the friction ratio,it can be found that between the waste soil of high landfill age and HDPE geomembrane,the contact surface is uniform can fully contact shear and can give full play and manifest the interface friction effect.(4)HDPE geomembrane as the middle cover of the landfill body critical sliding surface is disturbed,there is a certain slip along the membrane interface,so that the critical sliding surface in the different layers of the landfill body development,play a role in delaying the penetration of the upper slip surface,and block the formation of the lower landfill body slip crack zone,HDPE geomembrane and waste soil between the complex soil-membrane interface shear can reduce the expansion of potential slip surface inside the landfill body.During the growth of landfill age from 11 years to 20 years,the overall stability safety factor of HDPE geomembrane covered landfill increased by 28%(column point),30%(spraying)and 18.5%(glossy)than that of clay covered landfill.Geomembrane as an intermediate cover layer can be a good substitute for clay cover and play a good safety stabilization role for the whole landfill cycle of the landfill body.(5)Combined with the analysis of the expansion project of a plain-type landfill in Jiangsu,the influence of the middle covering layer of HDPE geomembrane on the analysis of slope stability is revealed,which verifies the above research conclusions.