scholarly journals Application of concrete‐filled steel tubular columns in gob‐side entry retaining under thick and hard roof stratum: A case study

2019 ◽  
Vol 7 (6) ◽  
pp. 2540-2553 ◽  
Author(s):  
Wanpeng Huang ◽  
Xuewen Wang ◽  
Yusan Shen ◽  
Fan Feng ◽  
Kai Wu ◽  
...  
Keyword(s):  
Tubular Columns ◽  
Hard Roof ◽  
Roof Stratum

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

Evolution and management of thick-hard roof using goaf-based multistage hydraulic fracturing technology—a case study in western Chinese coal field

2021 ◽  
Vol 14 (10) ◽  
Author(s):  
KaigeZheng ◽  
Tong Zhang ◽  
Jizhan Zhao ◽  
Yu Liu ◽  
Fei Yu
Keyword(s):  
Hydraulic Fracturing ◽  
Coal Field ◽  
Hard Roof ◽  
Multistage Hydraulic Fracturing ◽  
Chinese Coal

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

Target Stratum Determination of Surface Hydraulic Fracturing for Far-Field Hard Roof Control in Underground Extra-Thick Coal Extraction: A Case Study

2018 ◽  
Vol 52 (8) ◽  
pp. 2725-2740 ◽  
Author(s):  
Yiyu Lu ◽  
Tao Gong ◽  
Binwei Xia ◽  
Bin Yu ◽  
Fei Huang
Keyword(s):  
Hydraulic Fracturing ◽  
Coal Extraction ◽  
Far Field ◽  
Hard Roof

scholarly journals Case study on the mining‐induced stress evolution of an extra‐thick coal seam under hard roof conditions

2020 ◽  
Vol 8 (9) ◽  
pp. 3174-3185 ◽  
Author(s):  
Cong Li ◽  
Heping Xie ◽  
Mingzhong Gao ◽  
Jing Xie ◽  
Guangdi Deng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Stress Evolution ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Induced Stress

Influence of hard-roof on gas accumulation in overlying strata: A case study

2021 ◽  
Vol 90 ◽  
pp. 103948
Author(s):  
Yang Zhao ◽  
Baiquan Lin ◽  
Ting Liu ◽  
Wei Yang
Keyword(s):  
Gas Accumulation ◽  
Hard Roof ◽  
Overlying Strata

scholarly journals A Case Study of Effective Support Working Resistance and Roof Support Technology in Thick Seam Fully-Mechanized Face Mining with Hard Roof Conditions

2017 ◽  
Vol 9 (6) ◽  
pp. 935 ◽  
Author(s):  
Wei-bin Guo ◽  
Hong-sheng Wang ◽  
Guo-wei Dong ◽  
Lei Li ◽  
Yao-guang Huang
Keyword(s):  
Thick Seam ◽  
Hard Roof ◽  
Working Resistance ◽  
Roof Support

Effect of Premining on Hard Roof Distress Behavior: A Case Study

2019 ◽  
Vol 52 (6) ◽  
pp. 1871-1885 ◽  
Author(s):  
Weidong Pan ◽  
Xiaodong Nie ◽  
Xinyuan Li
Keyword(s):  
Hard Roof

scholarly journals An Innovative Approach for Gob-Side Entry Retaining by Roof Cutting in Steeply Pitching Seam Longwall Mining with Hard Roof: a Case Study

2020 ◽  
Vol 37 (4) ◽  
pp. 1079-1091
Author(s):  
Li Zhang ◽  
Jing Zhao ◽  
Chuanwei Zang ◽  
Shuanlin Wang
Keyword(s):  
Longwall Mining ◽  
Innovative Approach ◽  
Hard Roof
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