Study On Stability Of Overburden Bridge Foundation In Goaf Of Coal Mine

China is rich in coal resources,with the extensive exploitation of coal caused by water and environmental pollution,and mining subsidence caused by surface construction(structure)building damage,especially mining subsidence caused by the most serious consequences.With the development of China's infrastructure,the research on the stability of the mining subsidence and the foundation of the building is inevitable,but the traditional theoretical research methods are single,and the results of the study are different from the actual ones.It is necessary to adopt a more efficient and reliable method to study it and guide engineering practice.In this paper,taking the large bridge in Dahe Town,Liupanshui City,Guizhou Province as an engineering example,the geological,mining and rock mechanical parameters of the study area have been obtained by the field geological survey.Then,the stochastic medium theory is used to calculate the surface deformation of the mined-out area of Honglongzhai Coal Mine,and the three-dimensional model of the goaf is established by software(MIDAS GTS NX).The theoretical calculation and numerical simulation results are compared and analyzed and the location of the pier foundation is determined.The main achievements are as follows:(1)Based on the research results of mining predecessors in the field of mining subsidence,the advantages and disadvantages of the current mining and subsidence theory are analyze synthetically,and the deformation and failure characteristics of the overburden in the goaf and the law of surface movement and deformation are discussed.(2)This paper introduces the different expressions of the stochastic medium theory under the condition of fully inclined and fully exploited coal seams with different slopes,and discusses how to obtain the calculation parameters.(3)The subsidence,horizontal movement,inclination,curvature and horizontal deformation of the main section and the main section of the goaf are calculated by the stochastic medium theory.The software can simulate the subsidence,horizontal movement and stress.According to the theoretical calculation and simulation results,the current collapse state of the goaf and the damage level caused by the building are determined.(4)In combination with mined-out time,surface movement and deformation monitoring results,roof lithology and ratio of mining depth and working thickness determined that the current goaf is in a basically stable state.It is possible to collapse in goaf under the influence of groundwater,blasting,earthquake and upper load,and it is recommended that the pier foundation selected in the mined area outside the scope of influence.(5)The location of the pier foundation is determined by calculating the influence radius of the goaf along the inclination,and the influence of the bridge load on the stability of the overburden and the selected pier foundation is simulated by theoretical calculation and softare simulation.Finally,the reliability of the location is verified.