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Geomechanics and Engineering Volume 13, Number 2, August 2017 , pages 195-215 DOI: https://doi.org/10.12989/gae.2017.13.2.195 |
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Optimization study on roof break direction of gob-side entry retaining by roof break and filling in thick-layer soft rock layer |
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Dang-Wei Yang, Zhan-Guo Ma, Fu-Zhou Qi, Peng Gong, Dao-Ping Liu, Guo-Zhen Zhao and Ray Ruichong Zhang
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| Abstract | ||
| This paper proposes gob-side entry retaining by roof break and filling in thick-layer soft rock conditions based on the thick-layer soft rock roof strata migration law and the demand for non-pillar gob-side entry retaining projects. The functional expressions of main roof subsidence are derived for three break roof direction conditions: lateral deflection toward the roadway, lateral deflection toward the gob and vertically to the roof. These are derived according to the load-bearing boundary conditions of the main roadway roof stratum. It is concluded that the break roof angle is an important factor influencing the stability of gob-side entry retaining surrounding rock. This paper studies the stress distribution characteristics and plastic damage scope of gob-side entry retaining integrated coal seams, as well as the roof strata migration law and the supporting stability of caving structure filled on the break roof layer at the break roof angles of -5°, 0°, 5°, 10° and 15° are studied. The simulation results of numerical analysis indicate that, the stress concentration and plastic damage scope to the sides of gob-side entry retaining integrated coal at the break roof angle of 5° are reduced and shearing stress concentration of the caving filling body has been eliminated. The disturbance of coal mining to the roadway roof and loss of carrying capacity are mitigated. Field tests have been carried out on air-return roadway 5203 with the break roof angle of 5°. The monitoring indicates that the break roof filling section and compaction section are located at 0-45 m and 45-75 m behind the working face, respectively. The section from 75-100 m tends to be stable. | ||
| Key Words | ||
| thick-layer soft rock; break roof filling; gob-side entry retaining; filling support structure; break roof angle | ||
| Address | ||
| (1) Dang-Wei Yang, Zhan-Guo Ma, Fu-Zhou Qi, Peng Gong, Dao-Ping Liu: State Key Laboratory for Geomechancis & Deep Underground Engineering,China University of Mining and Technology, Xuzhou, China; (2) Dang-Wei Yang, Zhan-Guo Ma, Fu-Zhou Qi, Peng Gong, Dao-Ping Liu: School of Mechanics & Civil Engineering, China University of Mining and Technology, Xuzhou, China; (3) Guo-Zhen Zhao: College of Mining Engineering, Taiyuan University of Technology, Taiyuan, China; (4) Ray Ruichong Zhang: Divison of Engineering, Colorado School of Mines, Golden, CO, USA. | ||