Optimization and Practice on Method of Roof Control in Single-support Coalface for Ascending Mining

摘要

Based on the geology and mining technology conditions of III_2 coal seam in Xinzhuang Mine, the method of similar material simulation test was adopted to analyze the characteristics of overburden caving and weighting in coalface under ascending mining, and the software of Rock Failure Process Analysis System(RFPA~(2D)) was applied to simulate and analyze the roof control effect under different mining sequence and supporting method, then engineering practice was made in III_2-12111 coalface. The results showed: mining the III_2 coal seam under ascending mining, the periodical weighting was 6.7 m; compared with the method of four rows single-support in maximum roof control span and three rows single-support in minimum roof control span (shorting for three-four rows roof control method) in coalface, adopting the method of three rows singlesupport in maximum roof control span and two rows single-support in minimum roof control span (shorting for three-two rows roof control method), gob stowing was tighter, and hanging arch distance was reduced, and roof strata stress reduced by 10～15%; the observed result of mine pressure showed, adopting three-two rows roof control method (row space for 1.2 m, column space for 0.5 m) in coalface, compression of props and roof-to-floor convergence meet the requirements, it ensured the safely and efficiently mining in coalface, and obtained the largest monthly output of 30000 t, average monthly output of 26000 t. In the specific geological conditions, the method of ascending mining could enhance the mine production capacity and new well construction speed, ease the situation of panel replacing tension and production management decentralized, and achieve the purpose of safety and economy. But as a result of mining in the lower coal seam, the overburden structure of upper coal seam will be influenced in different degree, therefore, the method of roof control in working face needs further study when mining the upper coal seam[1]. The immediate roof of the upper III_2 coal seam in Xinzhuang Mine is fine sandstone, with thickness of about 10 m and high intensity, which belongs to thick hard roof. As mining the III_2 coal seam firstly is detrimental to the roof control, it is designed to mining under ascending mining sequence. Whether the choice of roof control method in blasting mining face under ascending mining condition is reasonable or not, it is directly related to the overall economic efficiency of mine. The study on reasonable roof control method when mining III_2 coal seam under ascending mining method in Xinzhuang Mine, could provide the theoretical basis for the construction of high yield and high efficiency mine.