Study on the Evolution Law of Overburden Breaking Angle under Repeated Mining and the Application of Roof Pressure Relief

Feng Cui, Tinghui Zhang, Xingping Lai, Jiantao Cao and Pengfei Shan
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Feng Cui: Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
Tinghui Zhang: Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
Xingping Lai: Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
Jiantao Cao: Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
Pengfei Shan: Energy School, Xi’an University of Science and Technology, Xi’an 710054, China

Energies, 2019, vol. 12, issue 23, 1-20

Abstract: Aiming at the serious problems caused by coal mine mining activities causing the rock burst accidents, this paper is based on rock mechanics and material mechanics to establish the key layer breaking by the double-key layer beam breaking structural mechanics model of a single working face and double working face under repeated mining. The theoretical calculation formula of the angle was used as the theoretical basis for the elevation angle of the pre-reloading hole of the hard roof. The rationality and reliability of the formula were verified by the physical similarity simulation experiment and the 3 Dimension Distinct Element Code numerical simulation experiment, revealing the rock formation under the influence of repeated mining. The results show that the derived key layer breaking angle formula is suitable for the theoretical calculation of the breaking angle of the key layer of a single coal seam when the repeated disturbance coefficient is λ = 1; when it is λ = 2, it is suitable for the repeated mining of the short-distance double-coal mining. The rationality and reliability of the theoretical formula of the breaking angle of the double key layer of single coal seam and double coal seam were verified by the physical similarity simulation experiment. Through the 3DEC numerical simulation results and theoretical calculation results, the W1123 working face hard top pre-cracking pressure relief drilling elevation angle was 78°. The drilling peeping method was used to verify the results. The results show that the theoretical formula of the critical layer breaking angle is well applied in engineering practice.

Keywords: double coal seam; repeated mining; critical layer breaking angle; roof pressure relief (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 (7)

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