Stability control of retained goaf-side gateroad under different roof conditions in deep underground Y type longwall mining

Stability of the retained goaf-side gateroad (RGSG) is influenced mainly by the movements of the roof strata near coal seam after coalface passes by. To make effective controlling technology for the stability of the RGSG, we analyze the roof structure over the RGSG to illustrate the mechanism causing the RGSG instability under different roof conditions. We then examine the dynamic evolution of the deformation and abutment stress in the rock surrounding the RGSG during coal seam mining, using the FLAC3D numerical software to reveal the instability characteristics of the RGSG under different roof conditions. Next, corresponding stability controlling technologies for the RGSGs are proposed and tested in three typical deep underground coalmines. Results show that: sink and rotation of the roof cantilever over the RGSG impose severer influence on the stability of the RGSG. The RGSG suffers disturbances three times during the coal-seam mining, and the deformation and abutment stress in the rock surrounding the RGSG increase significantly when the main roof becomes thicker and the immediate roof becomes thinner. Staged support technology involving grout cable bolts has better controlling results of the RGSG stability than that composed of conventional rock bolts, when the RGSG is beneath weak immediate roof with large thickness. Roof structure optimizing technology involving pre-split technology can improve the stability of the RGSG effectively when the RGSG is covered by hard main roof with large thickness directly.

[1]  Peng Xu,et al.  Evaluation of creep mechanical behavior of deep-buried marble under triaxial cyclic loading , 2015, Arabian Journal of Geosciences.

[2]  Ki-Il Song,et al.  Stabilization of Gob-Side Entry with an Artificial Side for Sustaining Mining Work , 2016 .

[3]  Xiexing Miao,et al.  Green and Sustainable Mining: Underground Coal Mine Fully Mechanized Solid Dense Stowing-Mining Method , 2017 .

[4]  Shinji Utsuki.  In-situ experimental studies on improvement of deformability of rock masses by grout treatment , 2011 .

[5]  Yong Chen,et al.  An innovative approach for gob-side entry retaining in highly gassy fully-mechanized longwall top-coal caving , 2015 .

[6]  Ki-Il Song,et al.  Extraction of Pressurized Gas in Low Air-Conductivity Coal Seam Using Drainage Roadway , 2017 .

[7]  Yunliang Tan,et al.  Design and construction of entry retaining wall along a gob side under hard roof stratum , 2015 .

[8]  Hideki Shimada,et al.  Application of Goaf-side Roadway Retained and New Type Ventilation System in Deep Longwall Face , 2015 .

[9]  A. Zolfaghari,et al.  Evaluation of rock mass improvement due to cement grouting by Q-system at Bakhtiary dam site , 2015 .

[10]  Jianguo Ning,et al.  An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining , 2017 .

[11]  Xiangyu Wang,et al.  An innovative approach for gateroad layout in highly gassy longwall top coal caving , 2013 .

[12]  Baiquan Lin,et al.  Stress redistribution of longwall mining stope and gas control of multi-layer coal seams , 2014 .

[13]  Nong Zhang,et al.  Optimization of gateroad layout under a remnant chain pillar in longwall undermining based on pressure bulb theory , 2016 .

[14]  Yuan Liang.  Gas distribution of the mined-out side and extraction technology of first mined key seam relief-mining in gassy multi-seams of low permeability , 2008 .

[15]  Nong Zhang,et al.  Position-optimization on retained entry and backfilling wall in gob-side entry retaining techniques , 2015 .

[16]  Rafael Jimenez,et al.  A probabilistic extension to the empirical ALPS and ARMPS systems for coal pillar design , 2012 .

[17]  E. Hoek,et al.  Trends in relationships between measured in-situ stresses and depth , 1978 .

[18]  K. N. Trubetskoy,et al.  Characteristics of methane release in highly productive coal mines , 2011 .