Analysis Of Deformation Characteristics Of Coal Mine Goaf In Xinhua-Ying'an Section Of Planned Dandong-Altai National Highway

With the high-speed and high-quality development of China's economic construction,the highway network has become denser and denser.Highways in some areas will inevitably pass through the goafs of old coal mines.Deformation and destruction of overburden layers in the mined-out area will cause deformation phenomena such as ground subsidence and horizontal movement,which will cause instability and damage to the roadbed across the mined-out areas,and even threaten the safety of structures such as highways.It will have a great impact on the operation and maintenance of China's highways and will also be detrimental to social and economic development.The planned national highway 331(Dandong-Altai)from Xinhua to Ying'an Section K11+780~K12+880 will pass from the northeast side of Ying'an Coal Mine in Hunchun.Since the mining of coal mines,there have been large-scale goaf subsidence areas in the underground.Goaf subsidence and surface deformation will become the key issues for the construction of highways.The paper selected the proposed National highway 331(Dandong-Altai)from Xinhua to Yingan section K11+780~K12+880 and the surrounding areas as the research object.By collecting many documents and many field investigating datas,the geological conditions and surface subsidence of the study area were analyzed.Probabilistic and integral method was the theoretical basis,the finite difference FLAC3 D numerical simulation software was used to study the surface deformation characteristics of the goaf.Synthetic aperture radar interferometry SBAS-InSAR technology was used to analyze and calculate the deformation rate in the study area.The research results of this topic will provide corresponding references for similar engineering problems.The main research conclusions obtained were as follows:(1)Based on the field surveys,geophysical prospecting,drilling,tilt measurement,and RTK deformation monitoring,the engineering geological and hydrogeological conditions of the study area and the mining conditions of coal seams were studied.It was obtained that there was no goaf within 150 m below the ground near the proposed highway;RTK displacement monitoring showed an average settlement of 9.65 mm for 6 consecutive months;the average of the cumulative north-south and east-west horizontal displacement of the inclinometer was 4.87 mm.The curve was oscillating with no upward or downward trend.(2)The probability integral method and the finite difference numerical simulation software FLAC3 D were used to calculate the residual settlement values of the ground deformation in the goaf,the maximum values were-150.5mm and-125.0mm,and the latter value was 71% of the former.The remaining horizontal displacement values were 45.1mm and 32.0mm,the latter value was 71% of the former.(3)The synthetic aperture radar interferometry SBAS-InSAR technology was used to analyze and calculate the deformation rate of the study area.It was found that the surface of the entire old goaf had subsided during the monitoring period in this year and a half,and the maximum deformation value of the area settlement was-6.94mm/a,which was located in the northwest of the study area.By calculation,it can be concluded that the average settlement value of the impact on both sides of the proposed highway within six months obtained from the surface subsidence monitoring using InSAR technology was-2.28 mm.