Research On The Stability And Risk Evaluation Method Of The Landfill Along Mountain Highway

A large number of landfills have been left in the mountains after the large-scale implementation of China’s highway construction.It is very necessary for judging the risk of these landfills accurately and swiftly then to propose solutions for the dangerous landfills,so as to ensure the safety of artificial facilities,buildings and the natural environment.In this dissertation,firstly,the methods of remote sensing image recognition,unmanned aerial vehicle(UAV)shooting,field investigation,combined with regional geological data and design data are used for comprehensive interpretation of the landfill.Secondly,composing in multiple factors and levels influencing factors obtained by interpretation information,indoor model test and material point method numerical simulation are carried out.The deformation and failure characteristics of slope under different conditions are obtained.Finally,according to the influence degree of the factors and the strength theory of soil slope by the limit equilibrium method,evaluation method of risk coefficient of landfill is proposed,which is verified and applied to practical projects.The main works and conclusions of the dissertation are as follows:(1)The remote sensing image,geological and hydrological conditions are integrated into a geographical coordinate system to comprehensively interpret the environment,elements and shape of the landfills.A remote sensing image interpretation method for the landfills is proposed.Through the comprehensive interpretation of remote sensing image,the information of landfills elements is obtained including stone content,quantity of landfill,shape of the landfill slope,slag retaining dam,the drainage system,bottom slope and the situation of spoil and rock-fall so on.It is used as the basic data source for the risk evaluation of the landfills.(2)Laboratory tests have been conducted to learn the process of slope failure.Point displacement,point pore pressure and the image of the failure processing have been achieved by the tests.Stone content and basement slope have been chosen as a major variable.The results show that:(1)the stability of the landfill decreases significantly with the decrease of the stone content,which also means the decreases of strength and permeability of the slag.(2)For soil samples with stone content≥50%,the bottom slope change has no effect on the stability of the landfill.For soil samples with stone content<50%,the stability of the landfill decreases with the increase of the bottom slope.(3)A dynamic simulation analysis model of high-risk landfill failure is established based on the material point method.The incidence of landfill risk influencing factors,including the stone content,the slag excess degree,the integrity of the slag retaining dam,the drainage conditions of the landfill,and the bottom slope are obtained.The simulation results show that:the stone content is the first main influencing factor.The slag excess degree is the second main influencing factor.The integrity of the slag retaining dam,the drainage conditions of the landfill and the bottom slope are auxiliary influencing factors,having the influence reduced in turn.The numerical simulation is verified through laboratory tests,and the numerical simulation results are consistent well with the indoor test results,whitch confirmed the validity and accuracy of numerical simulation.(4)The landfill stability influencing factors are chosen and analyzed by the results of the remote sensing recognition,the laboratory tests and the dynamic simulation analysis.A evaluation method for risk coefficient(P)and its limits are proposed based on the theory of limit equilibrium method using the landfill stability influencing factors and the importance factor.When P<1,the landfill is stable,low risk,and the displacement of the slope foot may D_S<0.5H(H is the high of the landfill);when 1≤P<5,the waste slag yard is unstable,medium risk,and the instability probability increases as P value decreases;especially,when P≥5,the waste slag yard is extremely unstable,high risk.A catastrophic landslide may be formed.The calculation method for risk coefficient of the landfill is verified by numerical simulation,and then it is applied to the risk evaluation of landfill in actual engineering.