Study About The Influence Of Goaf On The Stability Ofoverlying Railway Subgrade

China's mineral resources are very rich.With the rapid development of the economy,various transportation routes are becoming more and more dense,and mining resources will leave many goafs,which will not avoid many traffic routes passing through the surface of the goaf.Due to the existence of the goaf,the stability and deformation of the overlying rock mass are likely to be affected,which further causes the ground to settle,thus affecting normal production operations.Therefore,it is of great significance to study the influence of the goaf on the deformation and damage of the overlying rock mass and thus affect the stability of the pavement.The proposed railway special line is the infrastructure of a 300,000-ton zinc smelting project of a certain mining company in South China.The dedicated lines DK1+180~DK1+250 and DK1+380~DK1+780 are located in the third,fourth and fifth middle sections respectively.Above the mined area of the district and the sixth,seventh and eighth sections,the other sections are adjacent to the goaf.This means that the impact of the goaf on the proposed railway dedicated line base can affect normal production operations and further research is needed.This paper combines the proposed railway special line with the plane position map of the undercut goaf,and takes the influence of the 117 line,119 line,121 line,123 line and 127 line of a mining area on the proposed railway subgrade as the research object.According to the unique characteristics of ABAQUS finite element analysis software,ABAQUS finite element analysis software is used as simulation software,and each proposed analysis under the influence of these five lines,the proposed railway in the current goaf,railway construction period,railway operation Period stress cloud map and displacementcloud map of current mined area,railway construction period and railway operation period.The research results obtained are as follows:(1)According to the stress cloud map obtained by numerical simulation,it can be seen that before the construction of the proposed railway special line,a small-scale plastic damage zone appears at both ends of the roof of the goaf,and the roof of the goaf is under the railway construction and operation load.Although the plastic damage zone has been expanded to form a caving zone,the extent of the recoil is still limited to the vicinity of the goaf,and the caving zone is far from the surface.(2)The proposed vertical railway line is under the construction and operation.The maximum vertical displacement of the goaf is located at the center of the top of the landing area,and under the railway construction and operational loads,the top of the landing area The maximum vertical displacement is within 5 cm,indicating that the upper rock mass of the landing zone is stable.(3)Before and after construction,the ground displacement of the proposed railway line is within 5 cm,and the slope value is within 1 mm/m.The settlement and slope values are in line with the requirements for railway subgrade deformation,indicating the feeder railway.The undercut goaf will not affect the construction and operation of the railway.