Study On The Influence Of The Conversion Of Open-pit Mining Of Remaining Resources To Underground Mining On The Safety Of The Surrounding Environment

With the decreasing mineral resources,it is necessary to fully explore the recycling of waste resources while ensuring the safety of the mine and restoring the ecological environment of the mine.In this paper,we take Fushun West Open Pit Mine as the object of study,and discuss the impact of open pit to shaft worker residual resource mining on the stability of mine slope,design the optimal solution,and design mining damage prevention and control measures.It provides a reference value for the study of the impact of residual resource mining on the safety of the surrounding environment in similar mining areas.The main contents and research results of this paper are as follows:(1)Combined with numerical simulation and theoretical analysis,the typical section in the study area is selected,the slope stability and deformation characteristics under the conditions of open-pit mining and underground mining are calculated,the mechanism of overburden deformation induced by open-pit mining is summarized,and the more suitable open-pit mining slope angle is 22°.(2)The stability of the slope is initially determined based on the relative position between the well mining area and the open slope,and it is found that the relative position of the well mining area and the open slope directly affects the critical mining width of the well mining area.At the same time,the optimal and the worst position of the well mining area and the critical mining width of the well mining area under different relative positions were obtained.(3)With the use of MIDAS and FLAC3D numerical simulation software,we simulated and analyzed the deformation law under the two mining schemes,and found that under both mining schemes,the surface settlement range will gradually expand,and the maximum settlement location is distributed above the west two mining areas,with the maximum settlement value of about 0.11m.(4)Using digital image processing technology to quantify the surface deformation results,it is obtained that the proportion of surface settlement area caused by mining scheme I and scheme II is 17.9%and 24.3%respectively,and the settlement area under the two mining schemes is 2.506 km~2and 3.402 km~2respectively.The surface settlement after mining in scheme 2 is greater than that in scheme 1,so scheme 1 is a better mining scheme.(5)Based on the numerical simulation results and the modified frequency ratio model to evaluate the landslide susceptibility of the study area under the optimal mining scenario,it is found that the RFR for slope instability takes values between[0,14.23],and the surrounding environment and the slope as a whole are in a stable state when the residual resources of the study area are mined using scenario 1.By combining domestic and international experiences,the corresponding safety prevention and control measures are proposed for the surrounding rock and surface deformation and slope instability in the mine area before and during mining.(6)According to the measured values of the north gang of the mine area,it can be seen that the surface displacement activities at the A850,A900 and A1100measurement points are more obvious,while the surface at the A1100 measurement point is more stable.Combined with the predicted results to 2023 years A850,A900,A1000 monitoring points in the coal mining process need to strengthen the north gang slope to prevent landslide disaster;A1100 monitoring point displacement is still relatively small compared to other monitoring points,the need for full-cycle observation of the slope in this area to prevent landslide disaster occurred.During this period,the slope can be treated by slope cutting and load reduction and foot pressure.