Risk Analysis Of Coal Measure Soil Slope In C11 Bid Section Of Changli Expressway

A large number of Carboniferous Triassic coal measures strata are exposed along Chang-li expressway.In the construction process,the construction period and future operation safety of Chang-li expressway are seriously affected due to the failure to take timely protective measures after slope excavation and continuous rainfall infiltration.In this paper,based on the investigation of cutting slope of coal measure strata in C11 bid section of Chang-li expressway,the risk factors affecting the instability of coal measure soil slope are analyzed,and the risk assessment model of coal measure soil slope is proposed.Finally,the risk assessment before and after protection is carried out for K213 slope of Chang-li expressway.According to the characteristics of coal measure soil slope,the treatment scheme is put forward,and the treatment effect is good.The main work of this paper is as follows:(1)This paper discusses the common risk assessment methods of slope engineering,summarizes and analyzes the advantages and disadvantages of common risk assessment methods,aiming at the fuzziness and uncertainty in the risk research of coal measure soil slope,selects Fuzzy AHP as the risk assessment method of coal measure soil slope in this paper,and puts forward the process of risk analysis of coal measure soil slope.(2)Based on the field investigation of the topography,lithology and hydrogeological conditions of the slope along section C11 of Changli expressway,the types and failure characteristics of the coal measure soil slope along the line are summarized.Based on the coal measure soil slope engineering of C11 bid section of Changli expressway,field investigation was carried out on several coal measure soil landslides.This paper analyzes the risk factors of coal measure soil slope instability from the aspects of coal measure stratum lithology,geological structure,hydrogeological conditions,topography and engineering construction technology,so as to provide reference for the construction of risk evaluation index system of coal measure soil slope.(3)According to the characteristics and instability risk factors of coal measure soil slope,the hierarchical structure system of risk evaluation of coal measure soil slope is constructed,including five main factors: engineering properties of coal measure strata,topography,engineering construction technology,inducing factors and slope deformation characteristics,which are refined into 20 secondary indexes.AHP is used to calculate the weight value,and the membership degree of each index is determined qualitatively and quantitatively.(4)In order to establish the risk assessment model,the instability risk level and disaster risk level of coal measure soil slope are formulated.The instability risk of coal measure soil slope is divided into low risk(I),general risk(II),high risk(III)and great risk(IV).Referring to the guide for safety risk assessment of highway cutting high slope engineering construction,the instability risk of slope is divided into four levels,and the comprehensive risk assessment matrix of coal measure soil slope is established,and the risk acceptance criteria and relative standards of coal measure soil slope are formulated Risk control measures should be taken.(5)According to the risk analysis of K213 high slope of Changli expressway,the instability risk level is III,the disaster risk level is 4,and the comprehensive risk level is high risk,which is consistent with the actual situation and verifies the rationality of the risk assessment model.(6)On the basis of investigation and Research on the protection and prevention measures of cutting slope of coal measure soil along the line,the protection principles of coal measure soil are summarized.According to the results of risk analysis,aiming at the characteristics of coal measure soil slope and the causes of slope deformation and failure,K213 slope treatment measures are proposed.Finally,the risk assessment of K213 cutting slope protection is carried out.The calculation results show that the residual risk is low risk and the risk is acceptable.It shows that the comprehensive treatment measures of K213 cutting slope protection are feasible,such as cutting anti slide pile,cutting top brushing to reduce weight and drainage.At the same time,Midas software is used to simulate the treatment scheme,which also shows that the slope stability meets the requirements after two excavation unloading and adding anti slide pile.