Research On Surface Movement And Deformation Laws In Large Mining Height And Shallow Seam Of Xinmi Mining Area

The surface subsidence caused by coal mining destroy the land,buildings and structure seriously.There are many domestic architecture in No.22001 face of Chaohua coal mining influence scope.With the development of coal mining,the mining under buildings becomes of serious problem.To study the law of movement and deformation of rock strata and ground surface caused by underground mining has great practical value for the prevention of the under-well and upper-well disaster.Through building surface movement observation station,mining subsidence of large mining height and shallow coal seam has been measured in this paper.Based on the measured data,surface movement characteristics and relevant angle parameters were analyzed.According to the least square principle and curve fitting,the estimated parameters in probability integral method were confirmed.The results show that: the strike boundary angle is 39.4 °,the uphill boundary angle is 44.4 °,the downhill boundary angle is 49.2 °,the maximum subsidence angle is 89.0 °,the surface subsidence factor is 0.88,the starting distance is 40~50m,the average maximum subsidence velocity lag distance is 45 m,the average maximum subsidence velocity lag angle is 80.3°,the total time duration of surface movement is 314 d,and the intense sinking period is 68 d.At the same time,the characteristics of surface fissure growth were investigated and the distribution of discontinuous deformation were summarized.On the basis of the key stratum theory,the forming reason of surface fissures was analyzed.The results indicate that the root cause of surface fissures is the breaking of overlying key strata.Soft overlying rock and thick unconsolidated layers weakened the mining-induced stress,and then reduced the possibility of the development of step.Meanwhile,because of poor tensile capacity of loess layer,dense distribution and no step fracture characteristics was formed.