Abstract
Gob-side entry retaining technology with roof cutting (GERRC) has been widely used in flat and near-flat coal seam conditions, but its application under inclined coal seam is still very deficient. In order to further improve the application system of GERRC and overcome the application difficulties under special geological conditions, this paper takes the 43073 working face of Yixin coal mine as an example to research the GERRC with upper roadway under gently inclined thick coal seam. Firstly, the difficulties in the upper entry retaining with inclined coal seam are analyzed and the corresponding key technologies and system designs are put forward. Subsequently, the roof cutting and upper entry retaining are designed in detail according to geological conditions of test working face, and the roof cutting and pressure releasing effect is analyzed by numerical simulation to expound the stress distribution and pressure releasing mechanism of surrounding rock. Finally, the upper entry retaining field test is carried out to verify the feasibility and applicability of the technology and related designs. Through field monitoring, it is found that the weighting step increases significantly, the weighting strength decreases effectively on the roof cutting side, and the pressure relief effect is obvious. Meanwhile, the maximum roof to floor convergence is 361 mm and the maximum shrinkage of both sides is 280 mm, so the retained entry can meet the reuse requirement of adjacent working face.
Highlights
In the gob-side entry retaining technology of longwall mining, only one entry needs to be excavated during one working face mining and another entry is obtained by retaining during the adjacent working face mining
It can be seen that this technology is mainly used on near-flat thin or medium-thick coal seam in the existing research, but the application in thick coal seam or inclined coal seam is still insufficient because of the influences of rock pressure, entry support, goaf filling effect, and other factors. erefore, in order to further improve the application system of this technology and overcome the application difficulties under special geological conditions, this study takes the 43073 working face of Yixin coal mine as an example to carry out the adaptability study of Gob-side entry retaining technology with roof cutting (GERRC) with upper roadway under gently inclined thick coal seam condition
Taking the 43073 working face of Yixin coal mine of Longmei group as an example, this paper carries out the first test of roof cutting pressure releasing bob-side entry retaining technology with upper roadway under gently inclined thick coal seam condition
Summary
In the gob-side entry retaining technology of longwall mining, only one entry needs to be excavated during one working face mining and another entry is obtained by retaining during the adjacent working face mining. Zhang Sheng takes the 9301 working face of Tangkou coal mine as an example, using coal gangue, fly ash, and cement as filling materials, and successfully carries out gob-side entry retaining test by solid filling method [6]. Li Youcun takes the 21001 working face of Wangcun coal mine as an example and successfully carries out the gob-side entry retaining test in fully mechanized caving face by adopting entry roof reinforcement support measures using wooden stack, gangue bag high prestressing anchor cable, and so on [7]. Zhang Guofeng takes the 2422 working face of Baijiao coal mine as an example and elaborates the implementation process and matching monitoring method of the roof cutting pressure releasing gob-side entry retaining technology [12]. It can be seen that this technology is mainly used on near-flat thin or medium-thick coal seam in the existing research, but the application in thick coal seam or inclined coal seam is still insufficient because of the influences of rock pressure, entry support, goaf filling effect, and other factors. erefore, in order to further improve the application system of this technology and overcome the application difficulties under special geological conditions, this study takes the 43073 working face of Yixin coal mine as an example to carry out the adaptability study of GERRC with upper roadway under gently inclined thick coal seam condition
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