ASSESSMENT OF THE SUBSIDENCE RATIO be BASED ON SEISMIC NOISE MEASUREMENTS IN MINING TERRAIN

Subsidence process in the rock mass disturbed by mining can be complicated and can be faster or slower depending on the geological structure and physical and mechanical properties of the rock mass. changes in exploitation geometry; and changes in the rate of exploitation. The most frequently, the subsidence process develops over years in a way that is difficult to observe over a short period (days). It has been proven in practice of coal mines in Poland that Knothe's model describes subsidence process with high accuracy. It is based on treating the rock mass as a stochastic medium and describing subsidence with stochastic equations. It can be assumed that, the complicated stress field as a result of mining activities induce a series of displacements of different sizes in rock mass. The inelastic defonnation in rock mass is accompanied by a microseismicity that can be recorded and processed. We assumed that seismic noise with weak seismic events is a low-energy part of the microseismicity. We proposed an analytical solution to examine the distribution of the energy of the seismic noise during subsidence process development based on Knothe's model. In general a qualitative method of subsidence process assessment by the registration of the seismic noise was described.