Linming Dou

Quantitative analysis of seismic velocity tomography in rock burst hazard assessment

In order to quantitatively evaluate the relationship between the tomographic images of P wave velocity and rock burst hazard, the seismic velocity tomography was used to generate the P wave velocity tomograms during the retreat of a longwall panel in a coal mine. Subsequently, a novel index (bursting strain energy) was proposed to characterize the mining seismic hazard map. Finally, the structural similarity (SSIM) index in the discipline of image quality assessment was introduced to quantitatively assess the relation between the bursting strain energy index images and the tomographic images of P wave velocity. The results show that the bursting strain energy index is appropriate for quantitative analysis and seems to be better for expressing the mining seismic hazard than the conventional map. The SSIM values of the future bursting strain energy compared with the P wave velocity and the current bursting strain energy reach up to 0.8908 and 0.8462, respectively, which illustrate that the P wave velocity and the bursting strain energy both are able to detect the rock burst hazard region. Specifically, seismic velocity tomography is superior to the bursting strain energy index in the detection range and the precision and accuracy of detection results.

Spatial structure evolution of overlying strata and inducing mechanism of rockburst in coal mine

Abstract Spatial structure of overlying strata existed and evolved dynamically with the exploitation scope (boundary conditions) changes in coal mines and to induce rockburst. Based on the “key strata” theory, the integrated spatial structure of overlying strata was put forward, which was composed of “O–X” structure in the plane section and “F” structure in the vertical section. The formation and ongoing instability of the “O–X” and “F” structures were called as dynamic evolution cycle of the overlying strata. Three basic categories of “O–X”, “F” and “T” structures were defined, and the strata behaviors of each spatial structure were analyzed. According to energy theory, mechanism of rockburst induced by spatial structure instability was discussed. The research expanded the scope of traditional ground pressure theory and provided a guide for the prevention of rockburst and mining tremors induced by structure instability of overlying strata.