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Abstract

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 deformation 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.
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Abstract

This work presents the methodology for analyzing the impact of ground vibrations induced during the drilling of gas/oil exploration wells on the surrounding constructions, as well as on humans and the natural environment. In the primary stage, this methodology is based on measurements of ground vibrations induced by a specific type of drilling system in the so-called reference site. In the next stage, ground vibrations are estimated in similar conditions to another design site, these conditions are assumed for a given drilling system, treated as a vibration source. In both sites, special seismic and geotechnical data are collected to construct numerical models for dynamic analyses. Finally, if it is required, a protection system is proposed with respect to the drilling technology and local conditions. The methodology presented has been tested on the terrain of an active natural gas mine used as the design site, and located in the southeastern part of Poland. The reference site was placed in the terrain of a working drilling system in similar conditions in the central part of Poland. Based on the results of numerical simulations, one may verify the different locations of the drilling rig in the design site with respect to the existing industrial structure. Due to the hazard from destructive ground vibrations, a certain vibroisolation system was proposed at the design site. Based on the results of numerical simulations one could rearrange the components of the drilling system in order to provide maximum security for the surrounding structures.
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