Research Of The Mining Subsidence And The Deformation Mechanism In Tongchuan Mining Area

Tongchuan mining area, covered with loess, features in complex topography with deepcoal bed and thick bedrock. As the surface deformation brought by the underground mininghas its own particularities, the research on the regulation of coal mining subsidence plays animportant significance in the safe mining in Tongchuan mining area and even in the Westmining area.Based on the measured data of the ground subsidence in Tongchuan mining area, thisthesis builds the empirical formulas to predict the ground subsidence and uncovers theregulation of coal mining subsidence and its particularities with the experiment on equivalentmaterials and Flac3d numerical simulation. Furthermore, the thesis emphatically studies themechanism of mining subsidence and the reasonable working surface dimension ofsafe-mining in Tongchuan mining area.The main results of the thesis are as follows:(1) On the basis of the surface movement data from the observation station of surfacemovement in Tongchuan mining area, this thesis concludes the basic parameter of the surfacemovement data in Tongchuan mining area, and depending on the method of introducingparameter the thesis improves the formula for the prediction of mining subsidence andincreases its accuracy.(2) Through the application of the experiment on equivalent materials, the thesis studiesthe form, the range, and the regulation of the destruction by overlying rock movement underthe condition of high depth mining; Under the circumstance of average bed rock thickness andmining thickness being the same, the thicker the overlying rock is, the bigger the range of theaffected ground is and the smaller the coefficient of the ground depression is and the smallerthe caving angle is; The thesis studies the destructional form of the overlying rock movement,which determines the critical length of working face with the destruction by ground surfacemovement and its calculation parameter; The thesis illustrates that with the increase of the coal mining depth, the critical length of safe mining increases. The thesis also determines thedeformed angle value and its related parameter of ground surface movement under conditionsof high depth mining and non-full mining.(3) By the means of the Flac3d numerical simulation, this thesis systematically studiesthe mining subsidence in Tongchuan mining area. The thesis tests and verifies the standardsfor small working surface and the result from the experiment on equivalent materials thesafe mining size increases with the increasing of mining depth, and decreases with theincreasing of ratio of soil and rock; The length of safe mining decreases with the increasing ofgob mining breadth. The thesis also simulates the method of reserving a coal pillar in thecenter of mining surface to control mining dimension in order to realize the safe mining,which can better solve the problem of three-under mining and is suitable to be popularizedin the pressing coal places.(4) With the combination of the analysis results above and the measured data from theobservation station, the thesis concludes the formula to estimate the safe-mining dimension,which can effectively control the numerical value of ground subsidence. It not only reducesthe disruption of mining to ecological environment within an acceptable range, but alsoincreases the recovery rate of coal resources.