ABSTRACT:

This paper presents a case study on the application of hydraulic fracturing to destress abutment pressures. The study site was an entry of a longwall coal panel at Yuwu Coal Mine, Shanxi, China. The main roof of the panel consists of a massive sandstone layer which is not easy to cave after the extraction of coal, leading to high abutment pressures applied on the tailgate and a bleeder entry and the subsequently large deformation. Hydraulic fracturing was performed on a trial basis to “soften” the massive sandstone so that it can cave after the longwall face passes by. Extensive monitoring system was placed to evaluate the destressing effort of the hydraulic fracturing including vertical stress in the chain pillar and longwall panel, abutment pressures, and deformations of the tailgate. Numerical modeling using distinct element method was carried out to examine the related mechanisms of using hydraulic fracturing to destress abutment pressures caused by longwall coal extraction.

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