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Ground response of a gob-side gateroad suffering mining-induced stress in an extra thick coal seam

  • He, Fulian (School of Energy and Mining Engineering, China University of Mining and Technology (Beijing)) ;
  • Gao, Sheng (School of Energy and Mining Engineering, China University of Mining and Technology (Beijing)) ;
  • Zhang, Guangchao (School of Energy and Mining Engineering, China University of Mining and Technology (Beijing)) ;
  • Jiang, Bangyou (College of Energy and Mining Engineering, Shandong University of Science and Technology)
  • Received : 2020.03.26
  • Accepted : 2020.05.18
  • Published : 2020.07.10

Abstract

This paper presents an investigation of the ground response of a gob-side gateroad suffering mining stress induced by a 21 m-thick coal seam extraction. A field observation, including entry convergence and stress changes monitoring, was first conducted in the tailgate 8209. The observation results of entry convergence showed that, during the adjacent panel 8210 retreating period, the deformation of the gob-side gateroad experienced a continuous increase stage, subsequently, an accelerating increase stage, and finally, a slow increase stage. However, strong ground response, including roof bending deflection, rib extrusion and floor heave, occurred during the current panel 8209 retreating period, and the maximum floor heave reached 1530 mm. The stress changes within coal mass of the two ribs demonstrated that the gateroad was always located in the stress concentrated area, which responsible for the strong response of the tailgate 8209. Subsequently, a hydraulic fracture technique was proposed to pre-fracture the two hard roofs above the tailgate 8209, thus decreasing the induced disturbance on the tailgate. The validity of the above roof treatment was verified via field application. The finding of this study could be a reference for understanding the stability control of the gob-side gateroad in extra thick coal seams mining.

Keywords

Acknowledgement

This study was supported by the National Natural Science Foundation of China (No.51974317 and 51904164), Yue Qi Distinguished Scholar Project (800015Z1138) China University of Mining & Technology (Beijing), Fundamental Research Funds for the Central Universities (800015J6), the Natural Science Foundation of Shandong Province (ZR2018QEE001).

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