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Geomechanics and Engineering
  Volume 8, Number 4, April 2015 , pages 495-510
DOI: https://doi.org/10.12989/gae.2015.8.4.495
 


Numerical simulation of pressure relief in hard coal seam by water jet cutting
Dazhao Song, Enyuan Wang, Jiankun Xu, Xiaofei Liu, Rongxi Shen and Wenquan Xu

 
Abstract
    The applications of water jet cutting (WJC) in coal mine have progressed slowly. In this paper, we analyzed the possibility and reasonableness of WJC application to pressure relief in hard coal seam, simulated the distributive characteristics of stress and energy fields suffered by hard coal roadway wallrock and the internal relationships of the fields to the instability due to WJC (including horizontal radial slot and vertical annular slot) on roadway wallrock. The results showed that: (1) WJC can unload hard coal seam effectively by inducing stress release and energy dissipation in coal mass near its slots; its annular slots also can block or weaken stress and energy transfer in coal mass; (2) the two slots may cause "the beam structure" and "the small pillar skeleton", and "the layered energy reservoir structure", respectively, which lead to the increase in stress concentration and energy accumulation in coal element mass near the slots; (3) the reasonable design and optimization of slots' positions and their combination not only can significantly reduce the scope of stress concentration and energy accumulation, but also destroy coal mass structure on a larger scale to force stress to transfer deeper coal mass.
 
Key Words
    water jet cutting; pressure relief; energy dissipation; hard coal seam; numerical simulation
 
Address
(1) Dazhao Song, Enyuan Wang, Xiaofei Liu:
School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China;
(2) Dazhao Song:
Postdoctoral Research Station, Yongcheng Coal & Electricity Holding Group Co. Ltd., Yongcheng 476600, China;
(3) Enyuan Wang:
Key Laboratory of Gas and Fire Control for Coal Mines, China University of Mining and Technology, Xuzhou 221116, China;
(4) Jiankun Xu:
School of Mines, China University of Mining and Technology, Xuzhou 221116, China;
(5) Rongxi Shen, Wenquan Xu:
Shaanxi Coal and Chemical Technology Institute Co., Ltd., Xian, 710065, China.
 

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