Practice of Roof Cutting and Pressure Relief Roadway Retaining Along Goaf Technology in Deep and Shallow Hole Blasting Empowering Thin Coal Seam

In order to solve the difficult problems of tight succession between mining and driving, waste of coal pillar resources and others caused by single-wing mining in the 2102 working face of Shanxi Baoli Hesheng Coal Industry, based on the mechanical parameters testing of roadway surrounding rock and seam formation mechanism analysis of controlled blasting, a collaborative technology of "deep and shallow hole blasting+D-type energy gathering tube" is proposed. Through theoretical calculation and numerical simulation, the roof cutting height is precisely determined as the basic top upper boundary of 15.3 m. A combination blasting of deep hole (with a hole depth of 15.5 m, a charge amount of 9 kg) and shallow hole (with a hole depth of 8.4 m, a charge amount of 5 kg) is adopted, combined with the process of "advanced cutting+reinforcement support+U-type steel blocking gangue+single column support". The on-site application indicates that energy gathering blasting forms a directional fracture surface of 15.3 m, with a 30% improvement in roof cutting efficiency. The average subsidence amount of the blocking gangue column is 198.5 mm, the movement amount of the roadway roof and floor is 280 mm, and the movement amount of the two sides is 200 mm, all of them are controlled within a safe range. This technology improves the extraction rate by 8%, reduces the excavation amount by 1200 m, decreases costs by about 2.6 million yuan (including excavation cost and support material cost), eliminates 5 m protective coal pillars, recovers an additional 4500 tons of coal, and increases profits by 2.565 million yuan. The research results provide highly valuable references for the selection of mining technologies for mines with similar conditions, and help the industry make technological progress and efficient mining.