ORIGINAL RESEARCH article
Front. Mater.
Sec. Mechanics of Materials
This article is part of the Research TopicMechanical Response and Failure Mechanism of Rock Under Dynamic Disturbance and WaterView all 10 articles
Study on the Development Height of "Two Zones" Under Repeated Mining of Medium-Thick Coal Seams at Close Range
Provisionally accepted
- 1China Energy Group Ningxia Coal Industry Co., LTD.Shuangma No.1 Coal Mine, lingwu, China
- 2Ningxia Coal Industry Co., Ltd, Yinchuan, China
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The coal faces I0104105 and I0104204 of coal seams 4-1 and 4-2 in the I01 mining area of Shuangma No.1 Mine are taken as the engineering background. In this manuscrip, UDEC numerical simulation, similar material simulation, downhole drilling imaging method measurement, and empirical formula calculation methods are employed to address the high development of the "two zones" in close-range medium-thick coal seams during repeated mining. An analysis is conducted on the movement and collapse laws of overlying rocks under the separate mining of 4-1 coal and the repeated mining of 4-1 coal and 4-2 coal. The development height of the "two zones" under repeated mining is determined, compared, and verified against the empirical formulas. Linear analysis is conducted through on-site measurements and empirical formula differences. The existing calculation formula coefficients are corrected to propose an empirical formula for the development height of the "two zones" applicable to the Shuangma Mine. The results show that the "two zones" development height presents three significant stages under the repeated mining of medium-thick coal seams at close range: rapid growth, slow growth, and final stability. The height of the "two zones" is not simply added; however, a superposition effect is observed, which is closely related to the physical and mechanical parameters of the rock layers between coal seams, coal seam spacing, and coal seam thickness. The research results have theoretical significance and guiding value for determining the "two zones" height of the overlying rock under repeated mining of medium-thick coal seams at close range.
Keywords: Close range coal seam group, drilling imaging, height of "two zones", numerical simulation, Repeated mining, Similar material simulation
Received: 13 Sep 2025; Accepted: 04 Dec 2025.
Copyright: © 2025 Zhou, Wu, Kong, Liu, Yan and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Yaowen Wu
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