Directional Blasting Fracturing Technology for the Stability Control of Key Strata in Deep Thick Coal Mining

Haojie Xue, Yubing Gao, Xingyu Zhang, Xichun Tian, Haosen Wang and Di Yuan
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Haojie Xue: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Yubing Gao: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Xingyu Zhang: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Xichun Tian: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Haosen Wang: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Di Yuan: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China

Energies, 2019, vol. 12, issue 24, 1-19

Abstract: Under the conditions of high ground stress and mining disturbance, the strata breakage that is induced by mining is severe. Thus, it is critical to investigate the structural characteristics of key strata (KS) in deep thick mining. This study introduces an innovative technology, namely, directional blasting fracturing, in which an energy-gathering tube is installed in a borehole and an explosive is detonated to break the roof in a specified direction. A theory of balanced bulk filling is established based on the requirements of developing a voussoir beam structure, which can be used to effectively evaluate the percentage of bulk filling in gob and to determine to which structure the key strata belongs. Based on this theory, two types of novel structural models in the advancing and lateral directions of the longwall face are established and defined for studying the roof fracturing mechanism. Compared with a cantilever structure, Model C can develop a stable voussoir beam structure, limiting the rotation space of the KS and reducing both the peak abutment pressure and the dynamic disturbance time in the advancing of the longwall face. Model E is defined as when the technology of directional blasting fracturing effectively cuts a stress transfer path into the barrier pillar. The peak abutment pressures on the barrier pillar and auxiliary entry are smaller, and the dynamic disturbance time is shorter, which can effectively improve the stability of the auxiliary entry. The key parameters of directional blasting fracturing are designed and constructed, and they include the roof fracturing height, angle, and charge structure. The field application performance of this innovative technology at the longwall face of 3 −1 101 in Hongqinghe coal mine was evaluated by analyzing the chock pressure stress, the pillar pressure stress, and the deformation of the auxiliary entry during mining, which lays a foundation for the application of this technology in coal mines in China.

Keywords: deep thick mining; directional blasting fracturing; theory of balanced bulk filling; voussoir beam structure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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