scholarly journals Research on Control of Rib Spalling Disaster in the Three-Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xiaoqiang Cheng
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Simulation Experiment ◽  
Current Status ◽  
Soft Coal ◽  
Grouting Pressure ◽  
Working Face ◽  
Coal Wall ◽  
Soft Coal Seam ◽  
Seam Mining

Rib spalling disaster at the coal mining faces severely restricted the safe and efficient output of coal resources. In order to solve this problem, based on the analysis of the current status of rib spalling in the three-soft coal seam 1508 Working Face of Heyang Coal Mine, a mechanical model of sliding-type rib spalling was established and the main influencing factors that affect rib spalling are given. The mechanism of grouting technology to prevent and control rib spalling has been theoretically analyzed. A similarity simulation experiment is used to analyze the change law of roof stress under the condition of three-soft coal seam mining. The optimal grouting pressure is determined by a numerical simulation experiment. And, silicate-modified polymer grouting reinforcement materials (SMPGMs) are used in field experiments. After twice grouting operations in the 1508 Working Face, the coal wall was changed from the original soft and extremely easy rib spalling to a straight coal wall and the amount of rib spalling has been reduced by 57.45% and 48.43, respectively. And, the mining height has increased by 0.16 m and 0.23 m, respectively. The experimental results show that the rib spalling disaster of the three-soft coal seam has been effectively controlled.

The Adaptation Analysis of the Fully Mechanized Coal Mining Face of Huopu Mine’s Third Soft Coal Seam

2014 ◽  
Vol 1049-1050 ◽  
pp. 335-338 ◽  
Author(s):  
Fa Quan Liu ◽  
Xue Wen Geng ◽  
Yong Che ◽  
Xiang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Geological Condition ◽  
Soft Coal ◽  
Working Face ◽  
Mining Face ◽  
Soft Coal Seam ◽  
Working Resistance

To get the maximum coal in front of the working face of the 17# coal seam, we installed a longer beam which is 1.2m in length in the leading end of the original working face supports ZF3000/17/28, and know that working face supports’ setting load and working resistance are lower .We changed the original supports with shield supports ZY3800/15/33 that are adaptable in the geological condition and got the favorable affection.

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.

scholarly journals The Development Law of Mining-Induced Surface Cracks in Shallow Coal Seam Through Double Gullies Terrain: A Case Study in a Mine

2021 ◽  
Author(s):  
Mingjiao Lu ◽  
Xueyang Sun ◽  
Enke Hou ◽  
Cheng Li ◽  
Yonggang Zhang
Keyword(s):  
Coal Seam ◽  
Relative Position ◽  
Simulation Experiment ◽  
Slope Angle ◽  
Vertical Displacement ◽  
Surface Cracks ◽  
Maximum Width ◽  
Working Face ◽  
Shallow Coal Seam ◽  
Seam Mining

Abstract Mining-induced surface cracks in gullies in shallow seams seriously threaten the development of ecological stability and the safety of mine production. The development law of surface cracks in shallow coal seam mining through double gullies terrain was studied, by taking the Cao Jiatan coal mine in the Yushen Mining Area as a project example. The function T and its discriminant were first put forward to describe the relative position both the surface cracks and working face advanced in shallow coal seam mining through double gullies terrain. The relationship between valley parameters of double gullies terrain and the relative position of surface cracks development was discussed through numerical simulation experiment, similar material simulation experiment and theoretical analysis. The results showed that when the working face passed through the G1 gully, the development of surface cracks led the working face. There were four surface cracks with a maximum width of 23 cm, and the maximum vertical displacement was 11 cm; while passing through the G2 gully, the development of surface cracks lagged the working face. There were seven surface cracks with a maximum width of 79 cm, and the maximum vertical displacement was 45 cm. It can be concluded that the relative position of crack development is greatly affected by geological conditions, gully depth, slope angle, span and other factors of the gully, among of which the gully slope angle is the main influencing factor. T and |T| value has a certain correlation with the lagging distance, crack width, vertical displacement and the total number of cracks in a single gully.

scholarly journals Experimental Investigation into the Bedding Plane Slip Effect on the Overlying Strata Behavior in Longwall Top Coal Caving of Soft Coal Seam

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Hengfeng Liu ◽  
Jixiong Zhang ◽  
Nan Zhou ◽  
Qiang Sun ◽  
Meng Li ◽  
...  
Keyword(s):  
Coal Seam ◽  
Main Roof ◽  
Bedding Plane ◽  
Simulation Experiments ◽  
Physical Similarity ◽  
Soft Coal ◽  
Working Face ◽  
Slip Area ◽  
Soft Coal Seam ◽  
Overlying Strata

Bedding plane shear slip becomes more obvious in rock strata with quite different mechanical properties. A composite beam model considering the behaviors of the main roof and the immediate roof in the “three-soft” coal seam is established based on physical similarity simulation experiments and the slip theory in this paper. The movement and failure of the overlying strata and the mechanism of the bedding plane slip at the 2211 working face are studied by experimental and theoretical analysis. The results suggest that the front abutment stress distribution occurs 50 m ahead of the working face, the initial caving interval of the main roof is 55 m, and the peak stress appears at a distance 20 to 32 m ahead of the working face. The bedding plane slip areas can be divided into the obvious slip area and the slight slip area along the mining direction. The range of the obvious slip area becomes wider and the range of the slight slip area grows to be narrower as the working face advances. The bedding plane slip becomes steady after gradual increase and leads to the subsidence of the overlying strata in the “three-soft” coal seam. The observed initial caving interval of the main roof by field measurement is 51 m, which is consistent with the results of physical similarity simulation experiments and theoretical analysis. The results demonstrate that the beam slip model proposed in this paper is reasonable and able to describe the behaviors of overlying strata and bedding plane slip.

Pressure Regularity Study of Three Soft Complex Coal Caving Coal Face

2011 ◽  
Vol 217-218 ◽  
pp. 1641-1646
Author(s):  
Nian Jie Ma ◽  
Guo Dong Zhao ◽  
Chun Lei Ju ◽  
Chong Li ◽  
Xiang Zhong Dong
Keyword(s):  
Coal Seam ◽  
Mine Pressure ◽  
Related Factors ◽  
Thick Coal Seam ◽  
Factors Affecting ◽  
Soft Coal ◽  
Working Face ◽  
Distribution Rule ◽  
Mining Coal ◽  
Seam Mining

In order to grasp the movement rules of three soft coal caving complex working plane strata and stoping space surrounding rock and hydraulic support interactions relationship, improve the management of mining roof, to do research about the distribution rule of caused abutment pressure and shield support of initial supporting force, the work resistance and adaptability of coal seam. The first coalface of testing mine 1301 mining coal gangue is clip three soft and thick coal seam mining, adopt fully mechanized caving technology, choose ZF6400/17/32 type support screen type top coal caving hydraulic to support working face roof support, in order to provide better services for safe production in the working face, especially study on related factors affecting the observational of working mine pressure.

scholarly journals Macro and micro grouting process and the influence mechanism of cracks in soft coal seam

2021 ◽  
Author(s):  
Hui Yu ◽  
Housheng Jia ◽  
Shaowei Liu ◽  
Zhihe Liu ◽  
Baoyu Li
Keyword(s):  
Coal Seam ◽  
Great Influence ◽  
Simulation Method ◽  
Maximum Principal Stress ◽  
Tensile Fracture ◽  
Direction Parallel ◽  
Secondary Fracture ◽  
Soft Coal ◽  
Grouting Pressure ◽  
Soft Coal Seam

AbstractGrouting is an important method to reinforce soft coal roadway, and the presence of primary cracks in the coal body has an important influence on the grouting effect. With the discrete element simulation method, the grouting process of the soft coal seam was simulated. The mechanism of primary cracks on grouting was revealed, while the influence of fracture characteristics and grouting pressure on the grouting effect was analyzed. The results demonstrated that grouting in the soft coal seam involves the stages of seepage, rapid splitting, slow splitting, and stability. Due to the presence of primary cracks, the grouting diffusion radius increased significantly. Under the slurry pressure, the tensile stress concentration was formed at the crack tip, and the slurry split the coal once the splitting pressure was reached. In addition, the distribution characteristics of fractures are found to have a great influence on the grouting effect. It is observed that smaller fracture spacing is associated with a larger slurry diffusion radius and thus easier penetration of the primary crack tips. The fracture angle affects the direction of fracture propagation. The secondary fracture formed by splitting is a tensile fracture, which is more likely to extend along the direction parallel to the maximum principal stress. Overall, these simulation results have guiding significance for the setting of reasonable spacing of grouting holes in the practice of grouting engineering.

scholarly journals Rib Spalling 3D Model for Soft Coal Seam Faces with Large Mining Height in Protective Seam Mining: Theoretical and Numerical Analyses

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Shuai Liu ◽  
Ke Yang ◽  
Tong Zhang ◽  
Chunan Tang
Keyword(s):  
Coal Seam ◽  
Failure Process ◽  
3D Analysis ◽  
Coal Face ◽  
Soft Coal ◽  
Working Face ◽  
Protective Seam ◽  
Seam Mining ◽  
Protective Seam Mining ◽  
Cutting Height

Fully-mechanized mining of coal face with a large cutting height is generally jeopardized by rib spalling disaster in the working face. Preventive measures based on undisturbed coal seam conditions fail to provide safe predictions, as large-scale fractures in soft coal face frequently appear before excavation due to mining-induced stresses. This paper investigates a case study of the Paner Mine 11224 working face in the Huainan mine area, China, which features an overlying protected layer in the protective seam mining. To simulate the failure process in such a mine, we elaborated a simplified physical-mechanical model of a coal wall that underwent shear failure and sliding instability, in compliance with the triangular prism unit criterion. Similar simulation experiments, theoretical calculations, and borehole monitoring were used to comprehensively analyze the overburden fracture and movement after mining the lower protective seam. The development height of three overburden zones was determined, and the characteristics of the protected layer affected by mining were obtained. The results show that the failure is mainly related to the roof load, coal cohesion, internal friction angle, coal seam inclination, and sidewall protecting force. The key to limiting the frictional sliding of a slip body is to reduce the roof load and increase the sliding coefficient and cohesion of the main control weak surface (MCWS). Besides, a self-developed three-dimensional numerical calculation software RFPA3D (Realistic Fracture Process 3D Analysis), which considered the rock heterogeneity, was used to reproduce a weak triangular prism’s progressive failure process. The numerical simulation results agreed with the fracture pattern predicted by the theoretical model, which accurately described the rib spalling mechanisms in a soft coal face with a large cutting height and a protective layer.

scholarly journals Water Inrush and Failure Characteristics of Coal Seam Floor Over A Confined Aquifer

2021 ◽  
Author(s):  
Min Cao ◽  
Shangxian Yin ◽  
Bin Xu
Keyword(s):  
Coal Seam ◽  
Abutment Pressure ◽  
Water Pressure ◽  
Shear Stresses ◽  
Confined Aquifer ◽  
Working Face ◽  
Stress Coefficient ◽  
Coal Wall ◽  
Failure Depth ◽  
Seam Mining

Abstract Failure behaviors of the floor rocks under coal seam mining in the conditions of hard magma rock roof and confined aquifer are studied. Based on the theory of rock stresses and elasticity mechanics, the combined effects of the abutment pressure induced by the hard roof and by the water pressure under the thin aquicludes of the floor rocks were considered, and a mechanical model was constructed along the strike of the working face. An analytical solution of stress distribution was derived in the floor rocks, the distributions of vertical, horizontal and shear stresses were calculated. In combination with the in-situ measurement, the results show that: 1) when the periodic pressure caused by the roof collapse occurs on the working face, and the maximum stress concentration in the floor appears at the elastic-plastic junction in the direction of the strike of the working face. With the increase of the depth of the floor, the horizontal stress coefficient tends to decrease, and the corresponding shear stress coefficient isoline shows a “symmetric spiral” distribution and propagates downward to the floor at a certain angle with the vertical direction. This causes the floor rocks to generate compression and shear or tension and shear failure. 2) when the immediate roof of coal seam is the magma rock, the abutment pressure shows a trend of a slow increase initially and then a rapid increase later. The peak value of abutment pressure appears at the location of 4 - 6 meters from the coal wall of the working face, and the concentration coefficient of the abutment pressure is between 1.4 and 1.8. 3) according to the measurement and calculation of the failure depths of the floor at different positions under the same coal seam, it is found that the maximum failure depth appears near the coal wall of the working face. The failure depth reduces by 11.6% after the floor goes through “the roof caving and re-compaction”, which causes the fractures in the floor to close and the thickness of the effective aquiclude increases. In the un-mined area of the working face, the failure depth is 55% of the maximum failure depth. 4) both the theoretical calculation and the numerical simulation show that the failure depth of the floor increases obviously under the combined action of high vertical stress and the water pressure. Under the condition that the thickness of the aquiclude is relatively thin, the water pressure of the floor and pressure intensity of the roof are the sensitive factors to affect the maximum failure depth of the floor.

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