scholarly journals Study on Rock Burst Early Warning in the Working Face of Deep Coal Mines Based on the Law of Gas Emission

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Qinghua Zhang ◽  
Shudong He
Keyword(s):  
Rock Burst ◽  
Early Warning ◽  
Critical Value ◽  
Gas Emission ◽  
Distribution Law ◽  
Deep Mine ◽  
Gas Concentration ◽  
Research Results ◽  
Working Face ◽  
The Law

This study is aimed at predicting rock burst disasters in high gas mines. First, the distribution law and correlation of gas and stress in the F15-17-11111 working face of Pingdingshan No. 13 Mine were analyzed based on the coupling relationship between gas emission and stress in the working face. Next, the relationship between gas emission and stress distribution was revealed, and an early warning method of rock burst in the deep mine working face based on the law of gas emission was proposed and applied to the F15-17-11111 working face. Finally, the critical value of the gas concentration indicator for rock burst early warning in the F15-17-11111 working face was determined as 0.05%. The following research results were obtained. The gas emission and the mining stress in the F15-17-11111 working face are negatively correlated. Mechanically, their correlation satisfies the typical coupling. Besides, the critical value of the gas concentration indicator determined by the proposed early warning method boasts high accuracy in predicting rock burst disasters. It can be used as an early warning method for underground rock burst disasters to promote the safety of working face mining. The research results provide reference and guidance for the monitoring and early warning of rock burst disasters in deep high gas mines.

Gas Concentration Distribution Law in the Roadway after Coal and Gas Outburst

2015 ◽  
Vol 713-715 ◽  
pp. 314-318
Author(s):  
Chun Li Yang ◽  
Yi Liang Zhao ◽  
Xiang Chun Li ◽  
Yang Yang Meng ◽  
Fei Fei Zhu
Keyword(s):  
Concentration Distribution ◽  
Correlation Coefficients ◽  
Coal And Gas Outburst ◽  
Gas Emission ◽  
Distribution Law ◽  
Gas Concentration ◽  
Research Results ◽  
Gas Outburst ◽  
Whole Process ◽  
Secondary Disasters

Gas emission happens after coal and gas outburst, and it could cause secondary disasters in the roadway. Therefore it is necessary to research gas concentration distribution law in the roadway after coal and gas outburst, and theoretical basis for avoiding the occurrence of secondary disasters could be provided. Based on the above, Fluent is used to simulate gas concentration distribution law in the roadway during outburst. The research results show that gas velocity of the initial stage is larger in the whole process of gas outburst and gas emission impacts opposite walls in the form of jet in the roadway intersection. The flow changes direction and moves along the main airway and return airway. It produces countercurrent along the main airway. Because the pressure in the main airway is high, gas migration velocity becomes zero after a certain distance and is "back" to return airway. The higher the outburst velocity is, the longer the flow length is. Gas concentration variation with two kinds of different outburst intensities and position are regressed and it shows that correlation coefficients of power function are the highest. The research results have a certain theoretical value to prevent the occurrence of secondary disasters after coal and gas outburst.

scholarly journals The Law of Fracture Evolution of Overlying Strata and Gas Emission in Goaf under the Influence of Mining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Cheng Cheng ◽  
Xiaoyu Cheng ◽  
Rui Yu ◽  
Wenping Yue ◽  
Chao Liu
Keyword(s):  
Maximum Height ◽  
Gas Migration ◽  
Gas Emission ◽  
Pressure Relief ◽  
Gas Concentration ◽  
Fracture Evolution ◽  
Working Face ◽  
Simulation Results ◽  
The Law ◽  
Overlying Strata

Mining is associated with poor safety due to pressure relief gas emission from the goaf during the production period. The aim of this study was to explore a case study of the Wangjialing coal mine 12322 working face in Shanxi, China, through physical simulation and field observation. The mine is characterized by overlying strata fracture in goaf during the process of working face mining. A mathematical model of gas source emission from the working face and gas migration and the finite element COMSOL software were used to simulate the law of gas migration in the region with overlying strata fissures under the influence of mining. The simulation results were used to explore the law of distribution of pressure relief gas in goaf. Rational parameters of the high-level directional long borehole for the pressure relief gas extraction in goaf were designed based on experimental results. The results showed that the development of the region with overlying strata fissures is affected by mining. In addition, the “trapezoid platform structure” is formed after fracture areas are connected. The maximum height of the stope caving zone was between 26.8 m and 28.1 m, and the maximum height of the fracture zone was approximately 110 m. The gas concentration exhibited a saddle-shaped distribution on the cut surface of the direction of the strike. Furthermore, the gas concentration showed an overall upward trend from the intake airflow roadway to the return airflow roadway and gradually decreased after reaching the maximum. In the vertical direction, gas concentration increased with the increase in the layer, and the position of the highest point of gas concentration gradually shifted to the direction of the intake airflow roadway. Construction parameters of the high directional long borehole were designed through simulation results. After steady extraction and stable extraction, the maximum gas concentration in the upper corner of the working face was 0.49%, and the maximum gas concentration in return airflow was 0.34%. The findings of this study provide information on the law of fracture evolution of overlying strata and gas migration in goaf under the influence of mining. These findings provide a basis for reducing gas overlimit in the working face or return airway corner, thus improving the safety production capacity of the coal mine.

scholarly journals Research on Reasonable Width of Coal Pillars of Non-equal Width Isolated Working Face Heading Goaf in Deep Mine

2021 ◽  
Author(s):  
weili yang ◽  
Quande wei ◽  
Zhonghui Wang ◽  
Zhizeng Zhang ◽  
Xiaocheng Qu ◽  
...  
Keyword(s):  
Rock Burst ◽  
Critical State ◽  
Research Result ◽  
High Stress ◽  
Coal Pillar ◽  
Stress Monitoring ◽  
Equilibrium Relation ◽  
Deep Mine ◽  
Working Face ◽  
Coal Pillars

Abstract Setting reasonable coal pillar is a key to ensure safe mining of island coal face heading goaf in deep mine. With determination of reasonable width of coal pillars of non-equal width isolated working face 3201 in worked-out area in one mine in Shandong as the engineering background, a research was conducted on the mechanism of rock burst induced by and the reasonable width of coal pillars of isolated working face in worked-out area and the main conclusions are as follows: (1) the coal pillars of isolated working face 3201 in worked-out area changed from pillars with goaf on two sides→pillars with goaf on three sides→pillars with goaf on four sides, resulting in evolution of overlying strata from pre-mining static “┒-shaped” structure→“C-shaped” structure→“O-shaped” structure and corresponding spatial stress from “saddle-shaped” profile→“platform-shaped” profile→“arch-shaped” profile; (2) the rock burst was induced by coal pillars, because the high stress on coal pillars at critical state of a rock burst was greater than their comprehensive strength and induced a rock burst due to sudden instability; (3) by establishing a bearing and load model of coal pillars at critical state of a rock burst and based on the equilibrium relation, an method for estimating reasonable width of coal pillars of isolated working face in worked-out area in deep mine was derived and applied to the isolated working face 3201 in worked-out area, thus comprehensively determining that the width of coal pillars should be 130m. The field stress monitoring verified the reasonability. The research result is of great significance to prevention of rock burst induced by coal pillars of isolated working face in worked-out area in deep mine.

scholarly journals Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Li Chong ◽  
He Sifeng ◽  
Xu Zhijun
Keyword(s):  
Coal Mine ◽  
Concentration Distribution ◽  
Spontaneous Combustion ◽  
Concentration Field ◽  
Gas Migration ◽  
Coal Spontaneous Combustion ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Research Results ◽  
Working Face

The overrunning disaster of harmful gas tends to occur in the working face in thick coal seam with high gas concentration, as the fully mechanized caving stope has the characteristics of high mining intensity, high remnant coal, and high gas content. Therefore, the disastrous mechanism and concentration distribution of gas migration in fully mechanized caving stope are the theoretical basis for gas control scheme. Based on the 7607 working face in Wuyang coal mine, the gas emission quantity in working face is comprehensively analyzed by field measurement in this paper. The gas leakage field, oxygen concentration field, and gas concentration field in 7607 working face are simulated by establishing the equal proportional numerical model. Due to the increase of air leakage in working face caused by the high alley pumping drainage, the risk of coal spontaneous combustion is also analyzed, when gas extraction in goaf is carried out. The research results show that the gas drainage technology in high drainage roadway has a remarkable effect on the gas overrunning phenomenon. The gas concentration near the upper corner of the working surface has been reduced from 0.7%-1% to 0.5%. At the same time, it is necessary to pay attention to the risk of coal spontaneous combustion in the goaf for gas drainage in the high drainage roadway. The width of the oxidation zone in the goaf is about 25 m deeper than that before the drainage. Research results provide the references for gas control technology and coal spontaneous combustion prevention in similar working faces.

scholarly journals Research on Mechanism of Rock Burst in Key Working Faces under Thick Magmatite in Deep Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
WeiLi Yang ◽  
ZhiZeng Zhang ◽  
QuanDe Wei ◽  
XiaoCheng Qu ◽  
JingLin Wen
Keyword(s):  
Rock Burst ◽  
Control Measures ◽  
Mine Pressure ◽  
Shock Bump ◽  
Deep Mine ◽  
Speed Reduction ◽  
Working Face ◽  
Mining Safety ◽  
Prevention And Control Measures ◽  
And Control

The rock burst of key working faces under the thick hard rock in deep mine significantly threatens the mining safety of deep mine. In this study, the key working faces under typical deeply buried thick magmatite were adopted as the engineering background. The mine pressure characteristics during the mining in key working faces under thick magmatite in deep mine were measured and analyzed. Then, the evolution of overburden strata structure under the control of thick magmatite was explored based on the theory of mine pressure to conclude that the horizontal “carrier” load of broken rock beam, the vertical “loader” load, and the shock bump load from thick magmatite fracture are main sources of force behind the burst. Finally, the mechanism of rock burst was studied on the basis of the balanced relationship between loading and bearing. According to the results of research, the burst in key working faces under thick magmatite in deep mine was actually the instability burst of the key working face block. The bearing capacity and load of key working face block were constantly changing during the unstable movement of thick magmatite. The rock burst would occur in the event of any instability during the dynamic confrontation of “loading-bearing”. As per different burst sources, it could be divided into flexural loading burst of thick magmatite and shock bump burst of thick magmatite fracture. The mechanical conditions for each of the two bursts and the width calculation formula for the key working face free from overall instability burst were deduced. The research results were applied to key working face 12310. Meanwhile, the purpose of safe production following the principle of “No disaster in bumps, no harm under burst” was realized by implementing the “Four Keys” comprehensive prevention and control measures of “key monitoring + key speed reduction + key pressure relief + key support”.

scholarly journals Study on the gas emission width of coal seam pressure released by goaf in the deep mine

2021 ◽  
Vol 267 ◽  
pp. 01045
Author(s):  
Siqian Li ◽  
Jianjun Cao ◽  
Yonglei Xie
Keyword(s):  
Coal Seam ◽  
Economic Benefits ◽  
Gas Content ◽  
Discharge Zone ◽  
Distribution Law ◽  
Deep Mine ◽  
Coal Roadway ◽  
Working Face ◽  
Safety Production ◽  
Belt Width

The technology of driving along goaf has been widely used in the prevention of high ground stress and coal-gasoutburst in coal mining in our country. In this paper, the 11-2 Coal Seam of zhujixi coal mine is taken as the research object. Based on the test of drilling cuttings and residual gas content at different depths of solid coal at the goaf side and the research on the distribution law, it is concluded that the effective pressure relief drainage belt width at the goaf side of 11-2 Coal Seam after mining is 29m. Field practice has been carried out in the adjacent working face. The results show that the predicted indexes measured during the coal roadway driving period do not exceed the specified critical value, which verifies the rationality of the width of the discharge zone. The results provide a theoretical support for the reasonable layout of the continuous working face, improve the driving speed of the coal roadway, reduce the cost of gas control, improve the economic benefits of the mine, and ensure the safety production of the mine.

scholarly journals Comprehensive Control Method of Gas in Upper Corner of High Strength Fully Mechanized Coal Mine

2021 ◽  
Vol 233 ◽  
pp. 01009
Author(s):  
Huijun Duan ◽  
Shijun Hao ◽  
Xu Peng
Keyword(s):  
Coal Mine ◽  
Control Method ◽  
High Strength ◽  
Gas Content ◽  
Engineering Practice ◽  
Directional Drilling ◽  
Gas Emission ◽  
Gas Concentration ◽  
Working Face ◽  
Mining Face

Based on the problem of large gas emission and serious gas accumulation in upper corner of the intensive fully mechanized caving face, taking the fully mechanized caving face of Wangjialing Coal Mine in Hedong Mine as the research object, the main gas emission sources of the extremely intensive mining face with low permeability and low gas content were studied. The methods of gas extraction by inserting (burying) pipe in upper corner and directional drilling in upper corner were adopted and carried out. The application of engineering practice and comparative test of effect are carried out. The results show that the maximum extraction purity is 2.8 m³/min, the maximum gas concentration is 0.8% in upper corner, 3.11 m³/min in the high directional borehole and 0.71% in upper corner. After combined extraction, the total extraction purity is 1.33~7.93 m³/min and the fluctuation range of gas concentration in upper corner is reduced to 0.31~0.61% safe point. The effect of gas prevention and control in working face is remarkable.

scholarly journals Multiparameter Monitoring and Prevention of Fault-Slip Rock Burst

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Shan-chao Hu ◽  
Yun-liang Tan ◽  
Jian-guo Ning ◽  
Wei-Yao Guo ◽  
Xue-sheng Liu
Keyword(s):  
Rock Burst ◽  
Early Warning ◽  
Large Diameter ◽  
Early Warning Systems ◽  
Fault Slip ◽  
Pressure Relief ◽  
Stick Slip ◽  
Research Results ◽  
Rock Bursts ◽  
Induced Stress

Fault-slip rock burst is one type of the tectonic rock burst during mining. A detailed understanding of the precursory information of fault-slip rock burst and implementation of monitoring and early warning systems, as well as pressure relief measures, are essential to safety production in deep mines. This paper first establishes a mechanical model of stick-slip instability in fault-slip rock bursts and then reveals the failure characteristics of the instability. Then, change rule of mining-induced stress and microseismic signals before the occurrence of fault-slip rock burst are proposed, and multiparameter integrated early warning methods including mining-induced stress and energy are established. Finally, pressure relief methods targeting large-diameter boreholes and coal seam infusion are presented in accordance with the occurrence mechanism of fault-slip rock burst. The research results have been successfully applied in working faces 2310 of the Suncun Coal Mine, and the safety of the mine has been enhanced. These research results improve the theory of fault-slip rock burst mechanisms and provide the basis for prediction and forecasting, as well as pressure relief, of fault-slip rock bursts.

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