Study On Surface Settlement And Deformation Of Goaf In Multilayer Slow Inclined Coal Seam Underlying A National Highway In Hunchun City

China is a big country in coal mining and consumption.The ecological deterioration and collapse accidents caused by coal mining existed in the last period and it is difficult to stop.At the same time,China's economy is developing at a high speed,and road and railway construction has been advancing at an unprecedented speed in recent years.As the roads built are becoming more and more dense,roads and railways in some areas will inevitably pass through coal mining areas and cross the gobs.At the surface,the displacement,subsidence and inclination caused by the destruction of the rock surface in the goaf will cause the pavement to be torn,resulting in subsidence of the subgrade,and large-scale subsidence will occur,which will cause great harm to traffic safety.It is planned to build the 331 National Road Xinhua-Ying'an section K11+740 to K12+520 section to cross the northeast side of Ying'an Coal Mine and the west side of Baoshan Coal Mine.Ying'an Coal Mine and Baoshan Coal Mine have been extensively exploited in this area for a long time.There are a large number of goafs in the area,and there have been scenes such as ground subsidence,cracking of houses,and sedimentary water under farmland,which seriously threaten the local people's production and life.Therefore,it is particularly important to systematically study the coverage of the goaf,the extent of the spread,the deformation of the ground rock and the displacement.This paper takes the proposed settlement of the 331 National Road Xinhua-Yingan section from K14+000 to K11+740 and the ground subsidence in the vicinity.Based on the collection and compilation of a large amount of literature and survey data,the research content of the thesis is completed.Firstly,the geological environment conditions of the study area,such as stratum lithology,geological structure,hydrogeological conditions,coal mining status and goaf distribution,are analyzed and studied.According to the results of the on-siteinvestigation,the existing surface deformation phenomena and their distribution in the study area were compiled,and the deformation mechanism was explored.Then,using the probability integral method as the theoretical basis,the surface subsidence values of each goaf in the typical section of the study area are calculated by MATLAB software programming,and then the total settlement value of all coal seams in the typical section is stabilized.Then,based on the surveyed data of the mined-out area,FLAC3D(finite difference numerical simulation software)was selected to establish the numerical model of the goaf and analyzed,and the stress and deformation law of the goaf were obtained,and the probability integral was obtained.The results of the method were compared and analyzed to verify the reliability of the numerical simulation.Finally,the research results obtained in this paper are summarized,and the improvements that should be made in the future research are put forward.