scholarly journals Theoretical analysis of support stability in large dip angle coal seam mined with fully-mechanized top coal caving

Mining Scince ◽  
2020 ◽  
Vol 27 ◽  
Author(s):  
Yucheng Ji ◽  
Yinghua Zhang ◽  
Zhian Huang ◽  
Zhenlu Shao ◽  
Yukun Gao
Keyword(s):  
Theoretical Analysis ◽  
Coal Seam ◽  
Dip Angle

scholarly journals Key Parameters of Roof Cutting of Gob-Side Entry Retaining in a Deep Inclined Thick Coal Seam with Hard Roof

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 934 ◽  
Author(s):  
Jinzhu Hu ◽  
Manchao He ◽  
Jiong Wang ◽  
Zimin Ma ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Numerical Model ◽  
Coal Seam ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Coal Recovery ◽  
Rock Structure ◽  
Different Depths ◽  
Dip Angle

Gob-side entry retaining by roof cutting (GERRC) employed in a deep inclined thick coal seam (DITCS) can not only increase economic benefits and coal recovery, but also optimize surrounding rock structure. In accordance with the principles of GERRC, the technology of GERRC in DITCS is introduced and a roof-cutting mechanical model of GERRC is proposed to determine the key parameters of the depth and angle of RC. The results show that the greater the RC angle, the easier the caving of the goaf roof, but the length of cantilever beam increases. The depth of RC should account for the dip angle of the coal seam when the angle is above 20°. Increasing the coal seam dip angle could reduce the volume of rock falling of the goaf roof, but increase the filling height of the upper gangue to slide down. According to numerical model analysis of the stress and displacement of surrounding rock at different depths and angles of RC, when the depth of RC increased from 9 m to 13 m, the distance between the stress concentration zone and the coal side is increased. When the angle of RC increased from 0° to 20°, the value of roof separation is decreased. GERRC was applied in a DITCS with 11 m depth and 20° RC angle, and the field-measured data verified the conclusions of the numerical model.

scholarly journals Investigation of Hydraulic Fracturing Crack Propagation Behavior in Multi-Layered Coal Seams

2020 ◽  
Vol 10 (3) ◽  
pp. 1153 ◽  
Author(s):  
Shirong Cao ◽  
Xiyuan Li ◽  
Zhe Zhou ◽  
Yingwei Wang ◽  
Hong Ding
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Crack Propagation ◽  
Principal Stress ◽  
Fracture Propagation ◽  
Clean Energy ◽  
Burial Depth ◽  
Coal Seams ◽  
Initiation Pressure ◽  
Dip Angle

Coalbed methane is not only a clean energy source, but also a major problem affecting the efficient production of coal mines. Hydraulic fracturing is an effective technology for enhancing the coal seam permeability to achieve the efficient extraction of methane. This study investigated the effect of a coal seam reservoir’s geological factors on the initiation pressure and fracture propagation. Through theoretical analysis, a multi-layered coal seam initiation pressure calculation model was established based on the broken failure criterion of maximum tensile stress theory. Laboratory experiments were carried out to investigate the effects of the coal seam stress and coal seam dip angle on the crack initiation pressure and fracture propagation. The results reveal that the multi-layered coal seam hydraulic fracturing initiation pressure did not change with the coal seam inclination when the burial depth was the same. When the dip angle was the same, the initiation pressure linearly increased with the reservoir depth. A three-dimensional model was established to simulate the actual hydraulic fracturing crack propagation in multi-layered coal seams. The results reveal that the hydraulic crack propagated along the direction of the maximum principal stress and opened in the direction of the minimum principal stress. As the burial depth of the reservoir increased, the width of the hydraulic crack also increased. This study can provide the theoretical foundation for the effective implementation of hydraulic fracturing in multi-layered coal seams.

Study on Methods of Exploring the Loosening Radius of Deep-Hole Controlling Blasting

2013 ◽  
Vol 734-737 ◽  
pp. 650-655
Author(s):  
Wen Qing Zhang ◽  
Jian Liu
Keyword(s):  
Theoretical Analysis ◽  
Coal Seam ◽  
Gas Flow ◽  
Critical Factor ◽  
Field Investigation ◽  
Flow Index ◽  
Low Permeability ◽  
Deep Hole ◽  
Deep Borehole ◽  
Outburst Coal Seam

Deep borehole controlling blasting is one of the most popular methods which used to improve permeability of low permeability and highly gassy coal seam. Proper interval between blasting hole is the critical factor. On this paper, the theory and insufficiency of each method are discussed by theoretical analysis and field investigation. The result shows that, because of the complexity of outburst coal seam, the measuring result got by different methods is relative and declinational. We need to make a right choice according to the actual demand. And the method of gas flow index is quickly, visual and reliable, which to be worth paying the utmost attention to.

Numerical investigation of the effects of coal seam dip angle on coal wall stability

2017 ◽  
Vol 100 ◽  
pp. 298-309 ◽  
Author(s):  
Qiangling Yao ◽  
Xuehua Li ◽  
Boyang Sun ◽  
Minghe Ju ◽  
Tian Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Numerical Investigation ◽  
Coal Wall ◽  
Dip Angle

The Study on Roadway Layout in Coordination of Mining Coal Seams Base on Failure of Floor Strata

2014 ◽  
Vol 889-890 ◽  
pp. 1362-1374 ◽  
Author(s):  
Yong Zhang ◽  
Chun Lei Zhang ◽  
Chun Chen Wei ◽  
Ya Dong Liu ◽  
Shi Qing Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Simulation Software ◽  
Coal Seams ◽  
Group Coordination ◽  
Mining Coal ◽  
Two Sides

In order to make sure the reasonable roadway layout in lower seam of close coal mining group coordination in Lijiahao coal mine, firstly, applying the theoretical analysis and geological radar detection to get the influence depth of mining from the up coal seam 2-2 to the floor is about 20m, the results show that the thickness of complete strata is about 15m, then determining to use the outward alternate entries in lower seam roadway by using theoretical analysis. At last, determining the distance of outward alternate entries is 12-14m by using FLAC3D numerical simulation software to simulate the change of stress and displacement in roof floor and two sides of roadway.

Analysis of Three-Dimensional Numerical Simulationin Rlue of the Migration Rule of Overlying Strata in Thick Seam Mining with Soft of Daping Mine

2013 ◽  
Vol 718-720 ◽  
pp. 1934-1937
Author(s):  
Meng Lin Xu ◽  
De Shen Zhao
Keyword(s):  
Theoretical Analysis ◽  
Coal Seam ◽  
Three Dimensional ◽  
Fissure Zone ◽  
Thick Coal Seam ◽  
Thick Seam ◽  
Soft Coal ◽  
Soft Coal Seam ◽  
Seam Mining ◽  
Overlying Strata

In order to delve better what research methodology of height of water conducted fissure zone are, especially in mining of thick coal seam with soft, 3-D numerical simulationin was used to S2S9 face of Da Ping mine, it reveals the damage movement rule of overlying strata in mining roof-coal in "Three Soft" coal seam in the end . Thus it confirms the height of the water flowing fractured zone and tests the simulation result by the theoretical analysis and simple hydrology observation result. it provides a new idea for the application soft overburden in extra- thick seam mining technology.

Flexible roadway protection technology in medium-thickness coal seam with large dip angle

2018 ◽  
Vol 41 (24) ◽  
pp. 3085-3102
Author(s):  
Yanlei Wang ◽  
Jianxin Tang ◽  
Zhangyin Dai ◽  
Ting Yi ◽  
Xinyin Li
Keyword(s):  
Coal Seam ◽  
Medium Thickness ◽  
Protection Technology ◽  
Dip Angle

scholarly journals Ground Stress Distribution and Dynamic Pressure Development of Shallow Buried Coal Seam Underlying Adjacent Room Gobs

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ming Zhang ◽  
Chen Cao ◽  
Bingjie Huo
Keyword(s):  
Stress Distribution ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Dynamic Pressure ◽  
Coal Pillar ◽  
Horizontal Stress ◽  
Working Face ◽  
Ground Stress ◽  
Stress Environment ◽  
Coal Pillars

The condition of the coal pillars remained in the room-and-pillar gobs is complicated. The stresses loaded on the pillar floor may be transmitted and overlapped. It changes the stress environment of the lower coal seam roof, leading abnormal periodic weighting. In the procedure of coal seam 3−1 mining in the Huoluowan Coal Mine, the ground stress is high while the working face passing through the room pillars of overlying coal seam 2−2, leading to hydraulic shield being broken. In this paper, theoretical analysis, numerical calculation, and similar material simulation were used to analyse the stress environment of lower seam and the effect of coal pillars remained in close-distanced upper seam. The stress transfer model was established for the room pillars of coal seam 2−2, and the stress distribution of underlying strata was obtained based on theoretical analysis. The joint action of dynamic pressure of high stress-coal pillar with movement of overlying rock strata in the working face 3−1 under the coal pillar was revealed. The results showed that the horizontal stress and vertical stress under the large coal pillar of the room gob in coal seam 2−2 were high, being from 9.7 to 15.3 MPa. The influencing depth of vertical stress ranged from 42 m to 58 m. The influencing depth of horizontal stress ranged from 10 to 23 m. The influencing range of the shear stress was from 25 to 50 m. When the working face 3−1 was mined below the coal pillar of 20 m or 50 m, abutment pressure was relatively high. The stress concentration coefficient reached 4.44–5.00. The dynamic pressure of the working face was induced by the stress overlying of the upper and lower coal seams, instability of the inverted trapezoid rock pillar above the coal pillar, and collapsing movement of the roof. The studying results were beneficial for guiding the safety mining of the coal seam 3−1 in the Huoluowan Coal Mine.

The Influence of Formation Dip Angle on Buoyancy-Induced Gas Migration During Coal Seam Gas Production

2021 ◽  
Author(s):  
Mohammad Sedaghat ◽  
Des Owen ◽  
Philip Hayes ◽  
James Underschultz ◽  
Suzanne Hurter ◽  
...  
Keyword(s):  
Coal Seam ◽  
Gas Production ◽  
Gas Migration ◽  
Coal Seam Gas ◽  
Dip Angle ◽  
Formation Dip Angle
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