Abstract
Because of daily maintenance, equipment damage, gas overrun, and other force majeure factors, the continuous stopping of the working face causes the roof pressure to accumulate, which leads to causing accidents such as coal wall spalling and roof falling. To address the roof safety problem caused by continuous stoppages, the 620 working face in the Huangling mining area is taken as the research object. Through field measurement, theoretical analysis, numerical simulation, and other research methods, the influence and mechanism of stopping pressure under different rates of advance are studied. The results show that the velocity factor of roof load transfer is positively correlated with the advancing velocity of the working face; the reasonable length of the suspended roof is mainly affected by the number of caving holes and the effect of pressure relief; and comparing the two stages of advance speed of 4.8 m/d and 12.8 m/d, the periodic weighting step distance of the latter increases by 24.4% compared with the former, and the rate of increase of support load caused by stopping mining increases by 42.1% compared with the former. The roof pressure accumulation caused by stopping mining is increased. Taking appropriate measures for local forced caving of the working face can release the roof pressure and reduce the risk of local caving of the working face. The study can provide a theoretical basis for roof control of continuous stopping under similar engineering conditions.
Highlights
Due to force majeure factors such as daily maintenance of working face, equipment damage, special geological structures, and gas overrun, the continuous stoppage of mining in the normal advancing process of working face is inevitable, and the characteristics of ground pressure show obvious differences under different rates of advance [1]
Xie [2,3,4] analysed the failure field and stress field of the fully mechanised top coal caving face under different rates of advance through numerical simulation and similar simulation methods. e results show that when the unit mining depth increases, the extent of failure zones in the rock around the working face decreases, but a large amount of energy accumulates inside the rock mass, and the possibility of local rock burst increases; according to Yang and Liu [5, 6], the integrity of surrounding rock and the volume of broken rock block are positively correlated with the rate of advance of working face in shallow coal seams; S
When the working face stops mining for 1 day, the increment of abutment pressure changes most, with the increase of stoppage time, the increment of abutment pressure gradually decreases and diminishes; it can be concluded that the faster the rate of advance of working face, the greater the roof pressure caused by stopping mining
Summary
Due to force majeure factors such as daily maintenance of working face, equipment damage, special geological structures, and gas overrun, the continuous stoppage of mining in the normal advancing process of working face is inevitable, and the characteristics of ground pressure show obvious differences under different rates of advance [1]. Advances in Civil Engineering distance has not reached the collapse step distance, a large amount of energy accumulated in the roof cannot be released, the risk of a roof fall in the working face is greatly increased, and, at the same time, the hydraulic support movable column shrinks and the hydraulic pipe bursts In view of this kind of engineering problem, the author, by means of numerical simulation and field measurement, took the 620 working face of a mine in the Huangling mining area as the research background and investigated the ground pressure behaviour upon continuous stoppage at the working face in the process of high-speed advance thereof. Appropriate measures should be taken to release the roof pressure to ensure safe production at the working face
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