Analysis of mining earthquakes mechanism based on structural dynamics theory

LUO Shenghu; YAN Zhuangzhuang; XIE Panshi; WU Yongping; WANG Hongwei; ZHU Guangan; WANG Tong; TIAN Chengyang

doi:10.13225/j.cnki.jccs.2025.0259

Abstract：Mine earthquake is a common dynamic phenomenon in underground coal seam mining,and revealing its mech-anical mechanism is the premise and foundation for disaster evaluation,prediction,and prevention.In this paper,the theor-etical analysis method is used to investigate the mechanical principles and main control factors of the mine earthquake,and to study the sinking-vibration response characteristics of the overlying rock in the mine earthquake,and the evolution mechanism of the strain energy,gravitational potential energy and kinetic energy of the overlying rock under the action.The results show that mine earthquake is a typical type of free vibration from the perspective of structural dynamics.The mine earthquake is induced by the instantaneous instability of the coal-rock structure subsystem such as the fracture of the hard rock layer.After the transient,it is driven by the initial state of the coal-rock structure of the stope,and does not re-quire the input of external energy.Mine earthquake dissipates the potential energy(gravitational potential energy+strain energy)of coal and rock in the stope,which is controlled by the mechanical properties and mechanical environment of coal and rock structure in the stope and its corresponding transient characteristics.For the overlying strata above the struc-tural transient area,under the influence of the hard rock layer breaking,the load transfer path of the overlying strata has changed,the bearing capacity of the upper and lower surfaces of the key stratum above the goaf decreases instantaneously,and the bearing capacity of the upper surface of the key stratum outside the goaf increases instantaneously.Affected by this,the key stratum and its overlying strata sink and vibrate,and the response characteristics such as velocity,displace-ment and bending strain energy linear density at any time show fluctuation characteristics,and decay rapidly with the fo-cus of the mine earthquake as the center.Moreover,in any vibration period,there is energy dissipation and mutual conver-sion between different energies.In the first 1/4 period,the gravitational potential energy is converted to kinetic energy and strain energy.In the second 1/4 period,the gravitational potential energy and kinetic energy are converted to strain energy.In the third 1/4 period,the strain energy is converted to gravitational potential energy and kinetic energy.In the fourth 1/4 period,kinetic energy and strain energy are converted to gravitational potential energy.Based on the concept of this paper,the occurrence mechanism and internal correlation of coal-rock mechanical response in different areas of stope space dur-ing mine earthquake can be understood more intuitively,which provides new ideas and new perspectives for the preven-tion and control of coal-rock dynamic disasters.