Investigation into Pressure Appearances and Hydraulic Fracturing Roof-Cutting Technology in Mining Working Face under Residual Pillars: A Case Study

Abstract

Strong mining pressure disasters are prone to happen when the mining working face is under residual pillars (MWFRPs). The purpose of this study was to experimentally investigate and evaluate pressure manifestations and hydraulic fracture roof-cutting technology in the development of a working face under residual pillars using a physical model and numerical modelling tools. A scheme for hydraulic fracturing cutting technology was proposed and carried out on-site at the 31106 working face. The results show that the instability of the overlying residual pillar causes the upper thick, hard strata (THS II) to rupture and form a “T-shaped structure”. The rotation and sinking movement of the structure leads to the transmission of the dynamic load downwards, causing shear failure in the lower thick, hard strata (THS I) along the boundary of the residual pillar. The smaller the length of the THS II fracture block, the smaller the shear damage of THS I, and the lesser the mining pressure in the working face. Field trials proved that hydraulic fracture roof cutting can effectively destroy the integrity of the thick hard strata and promote their collapse, which reduces the strong dynamic load borne by the hydraulic support. This research provides a reference for safe mining at a working face under similar conditions.