The Seismic Dynamic Response Of Caol Mining Area

In order to study the seismic dynamic response of coal mine goaf and goaf group and the influence of goaf on the surface, Analysis of structural dynamics is made which is based on structural dynamics theory and the wave theory. The seismic dynamic response of coal mine goaf is made a systematic and quantitative analysis from change of the response of acceleration and displacement. Based on the latest research results of wave theory in the field of underground structure, this paper probes seismic dynamic response of the coal mine goaf and its influencing factors. Structural dynamics equation of motion is established which combined with the mining subsidence, structural dynamics, mechanics of materials and other related theory. By setting different peak acceleration of seismic wave, this paper discusses dynamic response law of coal mining goaf with different acceleration peak. TAFT seismic wave and artificial seismic wave are selected according to seismic design code which are used to numerical calculation of seismic dynamic response of the coal mine goaf and goaf group. The seismic dynamic response and its influencing factors are made a quantitative analysis and calculation results show that:Compared with the free field, the existence of mine goaf reduces the surface displacement and acceleration peak value and it obviously change dynamic response characteristic of the ground surface. The loose and fragmentation of rock medium increase, because the existence of mine goaf damage the integrity of the original site and change the original state of stress balance. Seismic wave dissipation energy increase during transmission, so the displacement and acceleration peak value is less than free field when the seismic waves spread to the surface.The influence factors of ground acceleration is analyzed at the same time, weakening of each point on the surface of acceleration above coal mining goaf reduce with the increase of buried depth; the acceleration peak of the surface also will increase as the stiffness of the rock increase; the more greater rigidity of goaf filling material is, the more greater acceleration peak of surface above filling area is.The method of numerical simulation is adopted to analyze seismic dynamic response of coal mine group and analyze different between single coal mine goaf and goaf group. Based on surface subsidence and rock damage theory, the evolution of stress field of coal mine goaf group is studied. with acceleration peak of input seismic wave increasing, rock stress is over stress intensity, overburden of coal mine goaf occurs bending deformation and supercharging zone occurs at both ends of coal pillar which increased pressure on coal pillar. Stress concentration appear at the top and bottom of pillars which is easily damaged.