Analysis of mine pressure factor of dynamic disasters to coal seam with large dip angle

2014 ◽  
pp. 791-794
Author(s):  
Guo Hao ◽  
Chen Li
Keyword(s):  
Coal Seam ◽  
Mine Pressure ◽  
Dip Angle ◽  
Pressure Factor

scholarly journals Characteristics of the Roof Behaviors and Mine Pressure Manifestations During the Mining of Steep Coal Seam

2017 ◽  
Vol 62 (4) ◽  
pp. 871-891 ◽  
Author(s):  
Tu Hong-Sheng ◽  
Tu Shi-Hao ◽  
Zhang Cun ◽  
Zhang Lei ◽  
Zhang Xiao-Gang
Keyword(s):  
Coal Seam ◽  
Field Measurement ◽  
Main Roof ◽  
Mine Pressure ◽  
Steep Seam ◽  
Working Face ◽  
Geological Conditions ◽  
Depth Study ◽  
Dip Angle ◽  
Similar Simulation

Abstract A steep seam similar simulation system was developed based on the geological conditions of a steep coal seam in the Xintie Coal Mine. Basing on similar simulation, together with theoretical analysis and field measurement, an in-depth study was conducted to characterize the fracture and stability of the roof of steep working face and calculate the width of the region backfilled with gangue in the goaf. The results showed that, as mining progressed, the immediate roof of the steep face fell upon the goaf and backfilled its lower part due to gravity. As a result, the roof in the lower part had higher stability than the roof in the upper part of the working face. The deformation and fracture of main roof mainly occurred in the upper part of the working face; the fractured main roof then formed a “voussoir beam” structure in the strata’s dip direction, which was subjected to the slip- and deformation-induced instability. The stability analysis indicated that, when the dip angle increased, the rock masses had greater capacity to withstand slip-induced instability but smaller capacity to withstand deformation-induced instability. Finally, the field measurement of the forces exerted on the hydraulic supports proved the characteristics of the roof’s behaviors during the mining of a steep seam.

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.

scholarly journals Roadway Surrounding Rock under Multi-Coal-Seam Mining: Deviatoric Stress Evolution and Control Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Dongdong Chen ◽  
En Wang ◽  
Shengrong Xie ◽  
Fulian He ◽  
Long Wang ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Deviatoric Stress ◽  
Mine Pressure ◽  
Coal Face ◽  
Surrounding Rock Control ◽  
Seam Mining ◽  
Peak Value

Multi-coal-seam mining creates surrounding rock control difficulties, because the mining of a coal face in one seam can affect coal faces in another. We examine the effects of multi-coal-seam mining on the evolution of the deviatoric stress distribution and plastic zone in the roadway surrounding rock. In particular, we use numerical simulation, theoretical calculation, drilling detection, and mine pressure observation to study the distribution and evolution characteristics of deviatoric stress on Tailgate 8709 in No. 11 coal seam in Jinhuagong mine when the N8707 and N8709 coal faces in No. 7-4 coal seam and the N8707 and N8709 coal faces in No. 11 coal seam are mined. The evolution laws of deviatoric stress and the plastic zone of roadway surrounding rock in the advance and behind sections of the coal face are studied, and a corresponding control technology is proposed. The results show that the peak value of deviatoric stress increases with the advance of the coal face, and the positions of the peak value of deviatoric stress and the plastic zone become deeper. The deflection angle of the peak stress after mining at each coal face and the characteristics of the peak zone of deviatoric stress and the plastic zone of the roadway surrounding rock under the disturbance of multi-coal-seam mining are determined. In conclusion, the damage range in the roadway roof in the solid-coal side and coal pillar is large and must be controlled. A combined support technology based on high-strength and high pretension anchor cables and truss anchor cables is proposed; long anchor cables are used to strengthen the support of the roadway roof in the solid-coal side and coal pillar. The accuracy of the calculated plastic zone range and the reliability of the combined support technology are verified through drilling detection and mine pressure observation on site. This research can provide a point of reference for roadway surrounding rock control under similar conditions.

Study on the Structure Characteristics and Ground Pressure Behavior of Overlying Strata with Shallow Buried Coal Seam

2011 ◽  
Vol 255-260 ◽  
pp. 3780-3785 ◽  
Author(s):  
Lei Yu ◽  
Zhi Zhong Fan ◽  
Gang Xu
Keyword(s):  
Coal Seam ◽  
Ground Subsidence ◽  
Mine Pressure ◽  
Structure Characteristics ◽  
Pressure Behavior ◽  
Ground Pressure ◽  
Working Face ◽  
Periodic Pressure ◽  
Seam Mining ◽  
Overlying Strata

The mine pressure behavior characters of shallow buried coal seam differed from both shallow seam mining and general depth seam. Mine pressure observation and numerical analysis were applied to research mine pressure behavior laws in fully mechanized face of shallow buried coal seam with thick bedrock and thin alluvium. It showed that the ground subsidence level phenomenon did not appear obviously although with obvious dynamic loading of fully mechanized face during the pressure period. The appearance was due to non-synchronized fracture from two key layers in the overlying rock layers and their interaction, which leaded to roof breaking initially and caving rocks with the form of an arch. Due to the periodic breaking and caving characteristics appearing as fully cut-down and arch alternately, the periodic pressure of shallow buried coal seam face showed as different size. The conclusion could be a reference for similar working face control.

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

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 An Influence Study of Face Length Effect on Floor Stability under Water-Rock Coupling Action

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Baojie Fu ◽  
Bo Wang
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Mine Pressure ◽  
Length Effect ◽  
Pressure Relief ◽  
Limestone Aquifer ◽  
Study Results ◽  
Face Length ◽  
The Face ◽  
Floor Stability

The Taiyuan Formation limestone aquifer and Ordovician limestone aquifer are widely distributed in the coal seam floor of coal measures in North China; the water hazard safety problem of the stope floor under the influence of mining is very prominent. The risk of the water inrush from the coal seam floor is closely related to the degree of full exploitation, so it is necessary to study the stability of the stope floor under aquifer conditions, especially the influence of the working face length effect on floor stability. Through numerical simulation of water-rock coupling action, the mine pressure behaviors of the water-resisting floor under different face lengths were analyzed based on the measured formation permeability coefficient. The Fish program was used to adjust rocks entering the plastic failure state into a strain softening model to investigate the influence of the face length effect, the damage degree of the water-resisting floor, and the morphology and deformation bearing capacity of the failure zone. The results show the following: (1) the face length effect is one of the main influence factors of the failure mode and failure degree of surrounding rocks in the stope; (2) as the face length increases, the obvious pressure relief zone of surrounding rocks presents a staged change, and the obvious pressure relief zone at the seam roof and floor is in an obvious “reverse saddle shape”; (3) the closer to the seam floor, the more remarkable the rock softening characteristic because of the compaction action of gangues caving from the roof; and (4) the rock mass close to the seam floor undergoes local tensile failure, and the water-resisting floor near the coal wall at two sides mainly bears compaction-shear action, leading to compression-shear failure of the rock mass at the floor and formation of water-conducting fractures. The study results can provide a reference for taking precautionary measures of safety mining above a confined aquifer.

scholarly journals Influence of Valleys Terrain on Pressure of Fully Mechanized Working Faces in Shallow Coal Seams

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
YingJie Liu ◽  
Qingjie Qi ◽  
Anhu Wang
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Rock Fracture ◽  
Mine Pressure ◽  
Overburden Rock ◽  
Coal Seams ◽  
Valley Bottom ◽  
Key Stratum ◽  
Seam Mining ◽  
The Impact

The absence of a key stratum during overburden rock movement is crucial to the mining pressure of fully mechanized coal mining faces. Using physical and numerical simulations, the 21304 mechanized mining in Daliuta and Huojitu coal mining faces 1−2 appeared twice during a pressure frame accident analysis. The results indicate that a lack of key overlying strata is crucial to the mining of lower coal seams, particularly for the upper sections of a single key stratum of coal. When the key stratum of the upper coal seam is absent, a stable masonry structure is formed after mining. It is easy to form stable stacked strata at the bottom of a coal seam. When developing gullies in deep terrains, the formation of the key stratum will be an upper rock fracture affected by the impact, resulting in a partial absence of the key stratum. When the key stratum is absent, the mining of upslope working faces and the probability of dynamic strata pressure increase with the overburden on the working face and mining of downslope faces. The face mine pressure development laws on the upper and lower coal seam mining were similar, mainly manifesting as “slope section >valley bottom section >back slope section.”

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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