Abstract
Exploiting the working face in coal mines using a super long mining length and large mining height has become important for intensive production with high yield and high efficiency. The paper develops a roof structure model to analyze the influence of 195 m, 242.4 m, and 376 m working face lengths at large mining height in Wangzhuang Coal Mine in China as the case study. The roof fracture characteristics, migration law, and strata behavior law under different working face lengths are compared and studied by numerical simulation, and the reliability of support selection in the working face at large mining height is analyzed by field measurement statistics. The results show that the roof fracture mode of a super large working face is a successive layered fracture. The length of the working face has little effect on the roof fracture step length, and the fracture step length is positively correlated with the thickness of the rock stratum. The roof subsidence law for a super large working face is different from the intermittent subsidence of the unimodal Gaussian distribution curve of ordinary working faces, which shows the intermittent subsidence of multiple ordinary working faces. The roof periodic weighting of a super large working face, which fluctuates violently within 100 m at both ends, is more drastic than that of an ordinary working face as a whole. Field statistical analysis shows it is more appropriate to choose high-strength support for a super large working face.
Highlights
With the rapid growth of the world economy, the market demand for coal continues to increase year by year, and highyield and highefficiency coal mines are increasingly common [1,2,3,4,5]
Full-height fully mechanized mining at one time has become an important technology for highyield and highefficiency mining in thick coal seams [6]
In addition to increasing the mining height, increasing the length of the working face has become a new direction for high yield and high efficiency working face mining [7]
Summary
With the rapid growth of the world economy, the market demand for coal continues to increase year by year, and highyield and highefficiency coal mines are increasingly common [1,2,3,4,5]. In 2005, Shangwan Coal Mine in Shendong Mining District built the world’s first fully mechanized coal mining face a lengthened working face with a large mining height of 300 m and average coal seam thickness of 5.5 m [15]. In 2008, Shangwan Coal Mine completed the design of a lengthened thick working face with a large mining height of 300 m and average coal seam thickness of 5.5 m, which is the world’s first fully mechanized mining working face with yield of over 10 million tons [15]. The working face length has experienced three stages: 242.4 m, 195 m, and 376 m, and the average thickness of coal seams is 5.02 m It is a fully mechanized full-seam large coal mining working face. This working face provides a practical basis for the comparative analysis of the mine pressure behavior law of working faces with different lengths, and it has vital theoretical and practical value
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