Study on Overburden Strata Rupture Development Height Rules in Repeated Mining of Thick Coal Seams

2012 ◽  
Vol 170-173 ◽  
pp. 279-282
Author(s):  
Nan Nan Zhao ◽  
Yong Jie Yang ◽  
Chang Qing Wang
Keyword(s):  
Coal Seam ◽  
Field Measurement ◽  
Development Time ◽  
Lower Layer ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Upper Limit ◽  
Mining Conditions ◽  
Overburden Strata

Take 3 coal repeated mining of Luxi colliery as research background, overburden strata rupture development rules in repeated mining of thick coal seam were studied by using the methods of field measurement. The results indicate that the height of overburden crack belt reduced along with the increase of goaf development time; the crack belt height of upper layer is 34.73m, the ratio of crack height and mining thickness is 15.1, the crack belt height of lower layer increased to 41.51m, but the increased trend declined, the ratio is only 12.14, the development height after up-layer was excavated is 83.6% of the height after two coalface were excavated. The results have important guiding sense for predicting overburden rupture rules in the similar mining conditions and improving the upper limit.

Numerical Simulation of Study on Rupture Development Rules of Overburden Strata in Repeated Mining

2012 ◽  
Vol 433-440 ◽  
pp. 1933-1939 ◽  
Author(s):  
De Chao Wang ◽  
Yong Jie Yang ◽  
Kai Wang ◽  
Nan Nan Zhao
Keyword(s):  
Numerical Simulation ◽  
Development Time ◽  
Lower Layer ◽  
Thick Coal Seam ◽  
Upper Limit ◽  
Measurement Results ◽  
Mining Conditions ◽  
Final Crack ◽  
Good Agreement ◽  
Overburden Strata

Take 3 coal repeated mining of Luxi colliery as research background, overburden strata rupture development rules in repeated mining of thick coal seam were studied by using the methods of field measurement and numerical simulation. The results indicate that the height of overburden crack belt reduced along with the increase of goaf development time; the crack belt height of upper layer is 34.73m, the ratio of crack height and mining thickness is 15.1, the crack belt height of lower layer increased to 41.51m, but the increased trend declined, the ratio is only 13.84; the final crack height of numerical simulation is 39.4m, in good agreement with measurement results. The results have important guiding sense for predicting overburden rupture rules in the similar mining conditions and improving the upper limit.

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.

scholarly journals Study on Rib Sloughage Prevention Based on Geological Structure Exploration and Deep Borehole Grouting in Front Abutment Zones

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Cheng Wang ◽  
Zuqiang Xiong ◽  
Chun Wang ◽  
Yuli Wang ◽  
Yaohui Zhang
Keyword(s):  
Coal Seam ◽  
Tectonic Stress ◽  
Geological Structure ◽  
Longwall Face ◽  
Mine Safety ◽  
Shanxi Province ◽  
Thick Coal Seam ◽  
Plastic Failure ◽  
Mining Conditions ◽  
Roof Strata

This research presents the grouting method of preventing rib sloughage which severely impacts mine safety and longwall retreat speed in thick coal seam with numerical simulation and laboratory tests. Based on the analysis of the plastic failure mode of five types of coal seam, roof strata ahead of the longwall face, and fractures developed in the coal seam, the following results are drawn, the range and degree of plastic failure generated in the coal seam and roof strata ahead of the longwall face gradually decreased as the coal mass strength increased; the grouting boreholes are essentially laid out within the coal rib instead of the roof. For a particular case of a coal mine in Shanxi province, a novel cement-based material was grouted, which fulfilled the reinforcement requirements under the tectonic stress regions and front abutment zones. Besides, the grouting borehole construction requested predrilled boreholes, full borehole intubation, lengthened hole sealing, and multiple-step drilling and grouting. This study can provide a theoretical framework of a design overview and practical basis for similar mining conditions in other coalfields.

Prediction of upper limit position of bedding separation overlying a coal roadway within an extra-thick coal seam

2018 ◽  
Vol 25 (2) ◽  
pp. 448-460 ◽  
Author(s):  
Hong Yan ◽  
Ji-xiong Zhang ◽  
Lin-yue Li ◽  
Rui-min Feng ◽  
Tian-tong Li
Keyword(s):  
Coal Seam ◽  
Thick Coal Seam ◽  
Coal Roadway ◽  
Upper Limit ◽  
Limit Position

scholarly journals The Study of Key Stratum Location and Characteristics on the Mining of Extremely Thick Coal Seam under Goaf

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Gaochuan Guo ◽  
Yongkang Yang
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Maximum Principal Stress ◽  
Engineering Practice ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Key Strata ◽  
Key Stratum ◽  
Arch Structure ◽  
Overlying Strata

The basis of traditional ground pressure and strata control techniques is the key strata theory, wherein the position of the key stratum can easily be determined for coal seams with regular thickness and without goaf. However, in the case of mining ultrathick coal seams underneath goaf, the traditional methods used for the calculation of key stratum position need to be improved in order to account for the additional coal seam thickness and the presence of an upper goaf. This study analyzed the failure height and collapse characteristics of overlying strata during excavation for determining the structure of the failed overlying strata. The results indicate that the intercalation and overlying strata gradually evolve into a large “arch structure” and a small “arch structure” during longwall mining, respectively. A mechanical model of the bearing characteristics of the interlayer key strata structure was established according to the structure of the intercalation rock layer, which is a hinged block structure. The results of the model indicate that the maximum principal stress occurs when the key strata portion of the arch structure bears the overlying load. Consequently, the movement and position of the interlayer key strata can be evaluated throughout the mining process of the ultrathick coal seams underneath goaf. This method was used to determine the position of interlayer key stratum of overlying strata in Xiegou coal mine. And the results agree with that of the engineering practice. The results are significant to determine the key strata position during ultrathick coal seam underneath goaf longwall mining.

Numerical Simulation and Analysis of Rock Burst Induced by Roof Movement

2014 ◽  
Vol 522-524 ◽  
pp. 1394-1398
Author(s):  
Tao Qin ◽  
Yong Li Liu ◽  
Chang Ji Dong ◽  
Ping Wang
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Coal Seam ◽  
Pressure Distribution ◽  
Coal Mine ◽  
Process Simulation ◽  
Hard Coal ◽  
Thick Coal Seam ◽  
Soft Coal ◽  
Mining Conditions

For composite thick seams have been incidents burst power disasters, and seriously affect the safety of the mine production.Based on the engineering background in coal mine, through the same mining conditions, stope mining process simulation which happens in single hard coal, soft coal and single composite thick Coal Seam of Island face were studied through comparative analysis by FLAC3D　numerical simulation technology. Tendency and trend of the pressure distribution results obtain through the comparative analysis . The research results has been applied in the actual coal mining.

scholarly journals Effect of roof movement on gas flow in an extremely thick coal seam under fully mechanized sublevel caving mining conditions

2019 ◽  
Vol 8 (3) ◽  
pp. 677-688
Author(s):  
Haijun Guo ◽  
Xianzhang Li ◽  
Hao Cui ◽  
Kaixuan Chen ◽  
Yuanyuan Zhang
Keyword(s):  
Coal Seam ◽  
Gas Flow ◽  
Thick Coal Seam ◽  
Sublevel Caving ◽  
Mining Conditions

scholarly journals Evolution Characteristics of Overburden Strata Structure for Ultra-Thick Coal Seam Multi-Layer Mining in Xinjiang East Junggar Basin

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 332 ◽  
Author(s):  
Xufeng Wang ◽  
Dongdong Qin ◽  
Dongsheng Zhang ◽  
Weiming Guan ◽  
Mengtang Xu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Junggar Basin ◽  
Structure Evolution ◽  
Thick Coal Seam ◽  
Roof Structure ◽  
Gravity Load ◽  
Evolution Characteristics ◽  
Fracturing Process ◽  
Overburden Strata

The efficient and safe extraction of ultra-thick coal seam in the Xinjiang East Junggar Basin has been a major focus in the future of mining in China. This paper systematically studied the overburden strata fracturing process and the structure evolution characteristics based on a typical ultra-thick coal seam condition in Xinjiang, using both physical and numerical modeling studies. The interactions between shields and the roof strata were also examined, from the perspective of ground support. The results indicated that roof structure was mainly in the form of voussoir beam at the early mining stage, where overburden stability was affected by the rock mass properties and mining parameters. The support load mainly included top coal and immediate roof gravity load and the load caused by main roof rotary consolidation. As a result of mining disturbance and strata movement, the overlying strata re-fractured in the later mining stage. The roof structure changed from beam to arch gradually and propagates upwards with the increase of multi-layer mining times. The support load was mainly the gravity load of the friable rock mass within compression arch. The results will provide a guideline for the improvement of roof stability under similar mining conditions in Xinjiang.

Gas Disaster Governance of Rock Cross-Cut Coal Uncovered in Extremely Inclined Outburst Coal Seam

2014 ◽  
Vol 962-965 ◽  
pp. 1147-1152 ◽  
Author(s):  
Hong Qing Zhu ◽  
Bei Fang Gu ◽  
Min Bo Zhang ◽  
Cheng Yi Yang ◽  
Xiang Shen
Keyword(s):  
Coal Seam ◽  
Computational Formula ◽  
Coal Seams ◽  
Minimum Thickness ◽  
Thick Coal Seam ◽  
East Region ◽  
Drilling Parameters ◽  
Geological Conditions ◽  
Outburst Coal Seam ◽  
Rock Pillars

Due to the complex geological conditions of Nanshan mine east region, the outburst predict index overrun frequently in the process of high-dipping extremely thick coal seam rock cross-cut coal uncovering, this text designed and optimized the front explore borehole parameter to ascertain conditions of coal seam; Optimized gas drainage drilling parameters to improve the rate of extraction, reduced the blank tape; On the basis of the theory of mechanics, derivate the computational formula of minimum safety rock pillars, identified with the minimum thickness safety of rock pillars. Through the above measures, guaranteed debunking coal seams quickly and safely.

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