Stability Analysis And Treatment Technology Of Goaf Under Highway

Coal in the western provinces of China is widely distributed.After mining coal seams,a large number of mined-out area are left in the mining area,posing potential hidden dangers for future construction.In order to ensure the safe operation of the project above the goaf,systematic evaluation of the stability of the goaf has become an important research topic before the construction of the project.This paper takes the control project of a goaf in Jincheng City,Shanxi Province as the research background,and uses theoretical analysis and numerical simulation to study the stability analysis and treatment technology of the goaf under the highway.The main contents and conclusions are as follows:(1)Based on the theory of elastic thin plate and the different types of mined-out area formed under the coal seam mining mode,the roof failure mechanics model is established.According to the actual form of deformation and deformation of the roof in the mined-out area and different boundary conditions,the deformation deflection equation of the roof of the mined-out area is derived.Using the strength theory,the basis for the evaluation of the stability of the mined-out area is obtained.(2)The probability integral method was used to predict the surface deformation in the mined-out area,and the surface subsidence,inclination,curvature and other curves were drawn after coal mining.According to the curves,the maximum surface subsidence in the study area was 2490.5mm.The log curve method was used to calculate the residual settlement in the engineering period,furthermore,the stability of the goaf was determined.(3)Based on FLAC3D software,the numerical simulation of coal seam mining process is carried out to study the variation of surface deformation and rock movement after coal seam mining.The maximum settlement of the study area is 2248.7mm,which can provide reference materials for the construction of the project.And by applying different loads to the numerical model,it is obtained that the surface settlement increases with the increase of the load after the end of coal seam mining or backfilling of the goaf;the surface settlement of the goaf after backfilling It is also small,ensuring the safety of the highway engineering above.(4)According to the theoretical prediction and numerical simulation results,combined with the actual situation of the site,the treatment plan of filling grouting method was designed.The field results show that the stress state of the overlying strata in the underground goaf is significantly improved,and the surface subsidence is significantly reduced,which proves the feasibility of the treatment plan.