Research on the temporal-spatial evolution of ground pressure at short-distance coal seams
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ORIGINAL PAPER
Research on the temporal-spatial evolution of ground pressure at short-distance coal seams Qian Liu 1,2 & Jianbin Huang 1 & Yusen Guo 1,2 & Tao Zhong 1,2 Received: 28 March 2019 / Accepted: 30 July 2020 # Saudi Society for Geosciences 2020
Abstract To study the temporal-spatial evolution of ground pressure at short-distance coal seams, this paper studied the displacement law of overlying strata and the temporal-spatial evolution of ground stress by analog simulation experiments. The results show when the upper coal seam is mined, overlying strata of the stope form three zones: the caved zone, the fractured zone and the bending subsidence zone. The caved zone which subsided in the largest quantity showed an irregular subsidence curve. The fractured zone where the maximum subsidence amounts are basically located in the middle of the goaf had approximately parabolic subsidence curves. The bending subsidence zone underwent the least subsidence as it was controlled by the key layer. In the coal mining process, stress concentrated in front of both the opening-off cut and the working face. When the working face advanced to 150 m, bearing stress of the opening-off cut and the working face was up to 20 MPa, with a stress concentration coefficient of 1.98. When the lower coal seam was mined, the immediate roof kept caving as the mining proceeded, with no obvious initial weighting or periodic weighting in the main roof. Only the roof stress within the mining area demonstrated greater fluctuations as the mining moved on. Pressures at the opening-off cut and the stopping line remained high in the whole process, so it is suggested to pay special attention to pressure detection during the first cut and make sure the roof is well supported for the mining of lower coal seam. Keywords Short-distance coal seamsground stress . Temporal-spatial evolution law . Analog simulation experiments
Introduction After coal mining, the stress balance of original strata is destroyed. In the process of stress redistribution, rock strata and the surface undergo continuous movement and deformation and discontinuous destroy (cracking, caving). This will lead to a series of subsidence and environmental disasters (Yu 2003) which are manifested mainly in three aspects: mine pressure (Yan 2009), mining fractures (Li et al. 2015), and surface subsidence (Wang et al. 2012). Among them, mine pressure will induce sinking, caving, and weighting of stope Responsible Editor: Murat Karakus * Qian Liu [email protected] 1
School of Resource Engineering, Longyan University, Longyan 364012, Fujian, China
2
Key Laboratory of Fujian Universities for Safe Mining of Mineral Resources, Longyan 364012, Fujian, China
and roadway roof and even lead to strong dynamic phenomena such as rock burst, endangering the safety of underground personnel and equipment. Many scholars have engaged themselves in the research on the migration law of overlying coal and rock after coal mining and put forward a variety of hypotheses and theories, including the press
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