Use of Tomography in Stress-Strain Analysis of Coal-Rock Mass by Solving Boundary Inverse Problems

摘要

The paper presents a seismic data interpretation approach to reconstruction of stress fields in rocks at any stage of coal mining. The approach involves: thee-axial compression testing of coal in order to find an empirical relation between elastic wave velocity and stresses;;coal bed tomography using standard monitoring systems and taking signals generated by dynamic events (with the energy higher than the background level) as the probing signals;;formulation and solving of a boundary inverse problem within a geomechanical model of an object under analysis where the input data is the velocity field reconstructed in the illuminated area of coal bed by tomography. The laboratory data of the coal specimens tested by the von Karman scheme have been approximated to plot analytical relationships between P-waves velocity, axial stress and confining pressure. The numerical experiments performed for a typical underground layout at coal producer "Vorkutaugol" have shown that given the accepted array of seismic pickups, the single-valued solution of the inverse problem requires good illumination of coal bed areas with the spatial stress gradient.