Presplitting cutting slots technique of roof cutting entry retaining and its impact on strata behavior law of workface in Baoshan coal mine

Abstract

Presplitting cutting slots advance working face is the key technology of non—pillar gob—side entry retaining formed by roof cutting and pressure release. And the rationality of parameters not only affects the formation of the structural surface of joint-cutting, but also has a significant impact on the retaining roadway. In order to enrich and improve the system of presplitting cutting slots technology, this paper takes the 6302 working face in Baoshan Coal Mine as the research object to discuss the effect of presplitting cutting slots technology on the strata behavior law of the working face. Then the presplitting cutting height, cutting angle and the distance between blasting holes are determined as the key parameters based on theoretical calculation. And the working face hydraulic support monitoring data are analyzed statistically. The research shows that: when the cutting height, cutting angle and the distance between blasting holes is 5m, 15 °and 500 mm respectively, the structural surface of joint-cutting can form through cumulative blasting. The influence range of pre-splitting roof joint-cutting technology on underground pressure is 30m. Furthermore, the average holding power of the powered support decreased by 3.8mpa, and the first weighting interval and periodic weighting length of the roof respectively increased by 4m and 5.5m in the affected area.

Research on gob‐side entry‐retaining technology with coal rib and corner strengthened support in soft rock strata

“…18,25 To summarize the research results, in terms of roof-cutting parameters, an applicable system can be identified for a certain selection of angle, height, hole spacing, and explosive structure. [26][27][28][29] Additionally, the new presplitting blasting method has achieved fruitful results. 30 In terms of support, studies on roof deformation mechanisms, 31 roof structure evolution characteristics, 32 roof control mechanisms, technology, and methods 33 have achieved fruitful results.…”

“…At present, GERRC has been successfully applied at shallow to deep depth, 19,20 for thin to medium coal seams 16,21,22 and thick coal seams, 23 in hard roofs to composite roofs, 17,24 and for highly dipping coal seams and broken roofs 18,25 . To summarize the research results, in terms of roof‐cutting parameters, an applicable system can be identified for a certain selection of angle, height, hole spacing, and explosive structure 26–29 . Additionally, the new presplitting blasting method has achieved fruitful results 30 .…”