Meitan kexue jishu (Mar 2023)
System and application of regional fracking of coal seam roof on and under the ground to prevent rockburst
Abstract
To solve the problems of small local relief range, low continuity and high operational risk of rockburst, regional hydro-fracking and burst prevention system and engineering application research were carried out within thick and hard roof of a coal seam by well over thousand meters on and under the ground. The results show that, according to the loading conditions, the roof dominated rockburst can be divided into three types: superposed dynamic and static loading type, high static loading type and high static unloading type; The thick and hard roof is the main source of regional static and dynamic loading for rock burst initiation of mining surrounding rock. With the thick and hard roof as the target, which provides the source of dynamic and static load for rock burst initiation, a segmented fracturing pressure relief system for the roof with 1000 meter horizontal holes on and under the ground was established and fracking was carried out in this area. By destroying the integrity of the overlying roof in the burst prone area in advance on and under the ground, the load is transferred to the more intact roof area, so as to provide a low stress operational environment for underground excavation and extraction, and also make the rock burst initiation conditions inapplicable. The fracking and burst control tests on the roof area using the horizontal well drilled on the ground before the extraction of the panel, and underground drilling from the entries during the extraction were carried out respectively. Remarkable results have been achieved in practice, forming a new disaster prevention and control mode of “fracking before construction” for burst prone coal mines under construction, and “fracking before tunneling, fracturing before mining” for the producing coal mines.
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