Abstract
Weak impact occurs during roadway excavation in some extremely thick coal seams in China. Although this hazard is not enough to destroy the roadway, it will cause fracturing and large deformation of the roadway surrounding rock, resulting in the fracturing of bolts and anchor cables and bringing great difficulties to roadway support. In the hope of solving this problem, firstly, the reason for impact occurrence in the roadway of the extremely thick coal seam is analyzed from the perspective of energy. Then, the surrounding rock fracture evolution in such a roadway is explored by means of numerical simulation, microseism, and borehole observation. Furthermore, the “pressure relief and yielding support” joint prevention and control technology is proposed and applied to Yili No. 1 Coal Mine. The field engineering application results show that the joint prevention and control technology can effectively reduce the impact energy and ensure the stability of the roadway surrounding rock in the extremely thick coal seam. The research findings can provide a theoretical foundation for the roadway support of the same type.
Highlights
Coal is the dominant energy in China
Multiple rock burst accidents have occurred in the driving faces (120–600 m deep) of over 10 extremely thick coal seams (8–50 m thick)
Roadway surrounding rock deforms seriously and quickly, which requires the supporting structure to have the properties of large deformation and yielding support
Summary
Coal is the dominant energy in China. In recent years, extremely thick coal seams in mining areas, such as Urumqi, Liuhuanggou, and Yili in Xinjiang, Huating in Gansu, Binchang in Shaanxi, and Yima in Henan, in western China suffer rock burst phenomena [1,2,3,4]. Roadway surrounding rock deforms seriously and quickly, which requires the supporting structure to have the properties of large deformation and yielding support Considering this requirement, foreign experts developed and designed energy-absorbing bolts such as the cone bolt, the Roofex bolt, the Garford bolt, and the D-bolt [25,26,27,28,29,30], and Chinese scholars conducted relevant research studies. In some extremely thick coal seams, the impact energy of the driving face and its near-field area is relatively small (smaller than 104 J), which belongs to weak impact When this kind of impact occurs, a vibration effect will be generated [40,41,42], inducing roadway surrounding rock vibration accompanied by a loud noise. The “pressure relief and yielding support” joint prevention and control technology is put forward based on the analysis of the mechanism of roadway impact in the extremely thick coal seam
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