| Most of the coal mines in our country are located in strong earthquake area, the seismic response analysis of coal mine goaf is an important technical reference for seismic design and seismic disaster mitigation. At present, there are few researches on the mechanism and law of the seismic response of coal mine goaf. The purpose of this paper is to reveal the seismic response characteristics of coal mine goaf, and to provide technical reference for seismic design of coal mine.Therefore, in this paper, the dynamic response of coal mine goaf is studied by using the wave theory and the numerical simulation.(1) Wave theory study on stress wave propagation in coal mine goaf based on stress wave attenuation by oblique incident free surface, joint surface reflection characteristics and surface mining goaf with depth were analysed. The principle of dynamic analysis, the explicit dynamic numerical calculation method, the modeling and numerical simulation of coal mine goaf dynamic analysis are described in detail.(2) Numerical simulation of three kinds of dynamic loads (based on pulse load, harmonic load, earthquake waves) and the influence factors of dynamic stability of coal pillar under (pillar diameter ratio, geological mechanics parameters and single component and multi-component load input) basic rules. The peak value of dynamic response of coal pillar under pulse load is at the end of pulse load. The dynamic characteristics of coal pillar under different harmonic frequencies are similar, but the peak value decreases with the increase of harmonic frequency. The peak value of the horizontal dynamic response of the coal pillar decreases with the height of the column, and the peak value of the vertical dynamic response varies with the height of the column.(3) The dynamic response equation of coal pillar under high geostress is established and solved analytically, and the mechanical characteristics of coal pillar under high ground stress are discussed. For the same dynamic load, the dynamic stability of the coal pillar is directly related to the ground stress, and the strong ground motion and the high stress state lead to the instability of the coal pillar. Study on dynamic characteristics and influencing factors of coal mine goaf under strong earthquake.Through the analysis of peak value and frequency spectrum of dynamic response, it is found that different mining depth has a significant influence on the dynamic response of goaf. Because of the influence of goaf on seismic wave propagation and reflection, the dynamic response of goaf surface is similar to the time history curve(4) The influence of different slope and mining depth on the peak value of surface ground motion is calculated and analyzed. The peak value of surface ground motion is closely related to the seismic wave spectrum,the lithology of stratum and the inclination of the goaf and the depth of mining. The calculation of seismic force in coal mine goaf area should be considered in deep mining and goaf slope effect on strong ground motions,the seismic force multiplied by a reasonable amplification coefficient can be used for seismic design of buildings in goaf. |
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