Abstract
Through the analysis of the mining situation and geological data of Qidong mine and working face, the key factors affecting the roof cutting and pressure relief roadway retention along the goaf are defined. Combined with numerical simulation and field test, the reasonable parameters of combined presplitting blasting of deep hole and shallow hole in hard roof are determined, and the roof cutting effect is tested through field observation and borehole peeping. The comprehensive control measures for the surrounding rock of 7135 roadway with roof cutting and pressure relief and gob retaining are formulated, including safety assurance technical measures, such as advanced precrack and seam cutting, roof reinforcement and support, gangue retaining protection beside the roadway, lagging temporary support, and on-site industrial test monitoring scheme. Aiming at the hard rock roof, the “deep hole + shallow hole” presplitting blasting roof cutting technology is developed, and the economic and reasonable blasting parameters are determined. The drilling peep results show that the implementation effect of presplitting blasting technology is good. The results showed that deep holes and shallow holes with small spacing and parallel to each other shall be arranged on the planned seam line. The peeping results show that the crack formation rate in the charging section exceeds 85% in the process of deep hole blasting. In shallow hole blasting, the crack formation rate of charging section is more than 90%.
Highlights
China and other major coal producing countries have invested more research on the technology of Retaining Roadway along goaf in order to reduce roadway excavation, improve the recovery rate of coal resources, ensure the continuity of production, and improve the economic benefits of mines [1,2,3,4]
Previous studies mainly focused on the adaptive conditions of retaining roadway, the deformation and failure mechanism of surrounding rock, the support methods beside roadway and in roadway, and the development of new filling materials
Wang et al [8] detailed the state of the art in research on top coal drawing mechanisms in Long wall top coal caving (LTCC) by examining the relevant literature over the past two decades
Summary
China and other major coal producing countries have invested more research on the technology of Retaining Roadway along goaf in order to reduce roadway excavation, improve the recovery rate of coal resources, ensure the continuity of production, and improve the economic benefits of mines [1,2,3,4]. Rough this research, a set of gob-side entry retaining technology system suitable for the mining area is formed, so that the excavation quantities of one mining roadway near the replacement face can be reduced, and the tension of mining replacement can be effectively alleviated. It can improve the maintenance conditions of high stress roadway along goaf with large mining depth and reduce the roadway maintenance cost. It can help realization of continuous mining without coal pillar, reduce the loss of coal resources, improve the recovery rate of mining area, increase the recoverable reserves of the mine, and prolong the service life of the mine
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