| Coal mining will break the stress balance state of surrounding rock,and the stress of rock and soil will redistribute under the action of self-weight,so that the rock and soil will move,deform and destroy.This process is a complex space-time process.The study of coal mining subsidence can provide guidance for goaf treatment,goaf safety evaluation and structure construction.In addition,seismic action will also make the rock and soil in goaf produce strain,even if the variable is very small,such as 10-6,it should also be paid attention to.Therefore,the study of coal mining subsidence and seismic dynamic response in goaf has practical engineering significance.Based on a certain goaf in Henan Province,this paper designs the indoor physical test of goaf when the coal seam is horizontal.Relying on the monitoring data of this test,firstly,the internal and surface settlement of rock and soil induced by coal seam mining is studied,and then the seismic load under different working conditions is applied at the bottom of the original model of goaf by using numerical software to analyze the response law of goaf.The main research contents and achievements are as follows:(1)The indoor physical test of horizontal coal seam mining is designed to study the law of coal seam mining settlement: the law of single point settlement is: the velocity increases from0,reaches the maximum at a certain time,and then decreases to 0,and the settlement curve is S-shaped;With the increase of buried depth,the settlement first increases rapidly,then increases slowly,and finally increases rapidly;With the distance away from the central axis of the goaf,the change rate of the settlement at a certain horizontal position is the largest,and the point with the largest change rate in this physical test is about 30 cm away from the central axis of the goaf.(2)Numerical simulation is carried out for the step-by-step mining of coal seam to study the settlement change law of the model surface points along the excavation direction.The result is that the surface settlement changes fastest in the initial stage of each step mining.The settlement data of corresponding monitoring points of physical test and numerical simulation are compared and analyzed,and the two are consistent.(3)Matlab is used to realize the surface subsidence prediction algorithm proposed in this paper.This algorithm can visually predict the surface point subsidence basin in the development stage and final stage of subsidence.The final subsidence stage of the prediction model is compared with the final subsidence stage of the physical model,and the predicted model value is consistent with the experimental value of the physical model.(4)By means of numerical simulation,the response laws of acceleration and additional displacement of surface sampling points and sampling points with different buried depth in goaf under different working conditions are studied,that is,the maximum acceleration of surface sampling point A is greater than that of underground sampling points with different buried depth,and greater than that of input working conditions,indicating that the acceleration amplitude is amplified at this point;The farther away from the central axis of the goaf,the greater the additional displacement of the surface point in X direction,and the greater the additional displacement in Z direction;With the increase of buried depth,the additional displacement in X direction is sampling point A > sampling point D > sampling point E,while the additional displacement in Z direction is sampling point D > sampling point E > sampling point A. |
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