scholarly journals Analysis of pressure relief and outburst prevention effect and mining depth effect of floor roadway in single serious outburst coal seam

2021 ◽  
Vol 267 ◽  
pp. 01051
Author(s):  
Guohong Chen
Keyword(s):  
Coal Seam ◽  
Field Test ◽  
Surrounding Rock ◽  
Test Results ◽  
Pressure Relief ◽  
Depth Effect ◽  
Mining Depth ◽  
Geological Conditions ◽  
Ground Stress ◽  
Outburst Coal Seam

In order to solve the serious problem of single serious outburst coal seam gas disaster, based on the gas geological conditions of Jiangxi Fengcheng Qujiang company, theoretical analysis, numerical simulation, field test and other comprehensive research methods were used to analyze the partition fracture law of roadway surrounding rock under different mining depth conditions. The results show that: under the conditions of high ground stress, high temperature and other environmental conditions, the radius of pressure relief loose circle of surrounding rock of roadway is significantly increased, and it is significantly larger than that of shallow part. In the deep area of - 800m elevation, the distance between floor roadway and coal seam is optimized to be 12 ~ 15m. The field test results show that the original permeability coefficient of overlying coal seam of floor roadway increases by 55.74 times, and the pressure relief effect is good.

scholarly journals Study of Gob-Side Entry Retaining Technology with Roof Cutting under Upper Roadway Condition

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xingen Ma ◽  
Manchao He ◽  
Xuewei Sun ◽  
Jianfeng Li ◽  
Gang He ◽  
...  
Keyword(s):  
Coal Seam ◽  
Surrounding Rock ◽  
Pressure Relief ◽  
Application System ◽  
Thick Coal Seam ◽  
Working Face ◽  
Geological Conditions ◽  
Key Technologies ◽  
Releasing Effect ◽  
System Designs

Gob-side entry retaining technology with roof cutting (GERRC) has been widely used in flat and near-flat coal seam conditions, but its application under inclined coal seam is still very deficient. In order to further improve the application system of GERRC and overcome the application difficulties under special geological conditions, this paper takes the 43073 working face of Yixin coal mine as an example to research the GERRC with upper roadway under gently inclined thick coal seam. Firstly, the difficulties in the upper entry retaining with inclined coal seam are analyzed and the corresponding key technologies and system designs are put forward. Subsequently, the roof cutting and upper entry retaining are designed in detail according to geological conditions of test working face, and the roof cutting and pressure releasing effect is analyzed by numerical simulation to expound the stress distribution and pressure releasing mechanism of surrounding rock. Finally, the upper entry retaining field test is carried out to verify the feasibility and applicability of the technology and related designs. Through field monitoring, it is found that the weighting step increases significantly, the weighting strength decreases effectively on the roof cutting side, and the pressure relief effect is obvious. Meanwhile, the maximum roof to floor convergence is 361 mm and the maximum shrinkage of both sides is 280 mm, so the retained entry can meet the reuse requirement of adjacent working face.

scholarly journals Study on Microseismic Monitoring, Early Warning, and Comprehensive Prevention of a Rock Burst under Complex Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ke Ding ◽  
Lianguo Wang ◽  
Mei Yu ◽  
Wenmiao Wang ◽  
Bo Ren
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Large Diameter ◽  
Elastic Strain Energy ◽  
Surrounding Rock ◽  
Control Effect ◽  
Pressure Relief ◽  
Working Face ◽  
Geological Conditions ◽  
Microseismic Events

Rock bursts in coal mines are usually unpredictable. In view of this problem, the energy–frequency relationship and spatial distribution characteristics of microseismic events during the mining of 5305 working face in Xinhe Coal Mine under complex geological conditions were analyzed in this study. Besides, the law and precursors of rock burst occurrence in this working face were discussed. The following research results were obtained. Before the rock burst occurred in 5305 working face, the energy and frequency of microseismic events vary in the following order: “peak-drop-rise-rock burst.” The analysis on spatial characteristics of microseismic events suggests that microseismic events were mainly concentrated at the boundary between the roof and the coal seam or at the hard roof near the coal seam within 0–160 m in front of the working face, and most of the events lay on the goaf side. Moreover, the energy and frequency of microseismic events both decrease in the above region before the rock burst occurred. This “microseismic event absence” phenomenon can be regarded as one of the precursors of rock burst occurrence. In addition, a multilevel antiburst scheme was proposed for the complex conditions: (1) to adopt large-diameter boreholes pressure relief technology and key layer high-level pressure relief technology for adjusting the stress distribution in the surrounding rock of crossheading in front of the working face and dissipating elastic strain energy; (2) to determine the advance speed to be 1.5 m/d for reducing the mining disturbance; (3) to adopt full-section reinforced support of the roadway for enhancing the antiburst capacity of surrounding rock. After the implementation of this scheme, the energy and frequency of microseismic events monitored on-site changed gently, and 5305 working face was safely recovered to the stop line position. The scheme boasts a remarkable rock burst prevention and control effect.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

Research on Mining Technological Parameters of 7# Thin Coal Seam in Liuquan Mine

2012 ◽  
Vol 629 ◽  
pp. 937-942
Author(s):  
Dong Sheng Zhang ◽  
Xu Feng Wang ◽  
Yang Zhang ◽  
Jin Liang Wang
Keyword(s):  
Coal Seam ◽  
Distinct Element ◽  
Horizontal Displacement ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Technological Parameters ◽  
Thin Coal Seam ◽  
Geological Conditions ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

Aimed at the specific geological conditions of 7# thin coal seam in Liuquan Mine, this paper used the methods of numerical calculation and theoretical analysis to determine the reasonable technological parameters of high-grade conventional mining face. The numerical simulation software of UDEC (Universal Distinct Element Code) was used to contrast and analyse the characteristics of surrounding rock stress distribution and overlying rock horizontal displacement under the condition of different length of coalface, then it was indicated that the surrounding rock deformation was less when length of coalface was 110 m which was advantageous for roof control; according to the conditions of roof and floor, the roof support strength was being calculated systematically to determine the row space of props being 700×1200 mm; the main equipments of coalface was assorted, and reasonable work manner in coalface and gob processing measure was put forward, which provided guidance for efficient mining in thin coal seam.

scholarly journals The method for determining working resistance of advance support bracket in deep fully mechanized roadway based on Flac3D

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878362 ◽  
Author(s):  
Guanghui Xue ◽  
Jijie Cheng ◽  
Jian Guan ◽  
Jingxuan Chai ◽  
Guofeng Zhang ◽  
...  
Keyword(s):  
Coupling Model ◽  
Surrounding Rock ◽  
Numerical Calculations ◽  
Stress And Strain ◽  
Determination Method ◽  
Mechanical Coupling ◽  
Mining Depth ◽  
Geological Conditions ◽  
Working Principle ◽  
Working Resistance

Fully mechanized roadway is an area of high accident incidence, and the problem is more prominent with the increase of mining depth of coal resources. The advance support scheme put forward for fully mechanized mining roadway with self-moving support and anchor combined unit, and the configuration and working principle of support robot was explicated. A determination method on the working resistance of advance support bracket was proposed based on mechanical coupling model of surrounding rock-advance support brackets. Taking the geological conditions of the Qishan mine as an example, the process of analyzing and determining the working resistance of the advance support bracket was described using this method. An advance support bracket was designed using SolidWorks, and the working load was obtained based on numerical calculations. Then the stress and strain were analyzed using ANSYS. The results showed that the designed advance support bracket can withstand the corresponding top plate pressure. It provides a new method and thought for study and development of advance supporting equipment in deep fully mechanized roadway.

scholarly journals Study on Borehole Arrangement Methods for Gas Extraction by Hydraulic Slotting in Long-Distance Through-Coal Seam Tunnel

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Cunfang Zhu ◽  
Shuang Cai
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Simulation Models ◽  
Gas Production ◽  
Gas Extraction ◽  
Long Distance ◽  
Pressure Relief ◽  
Coal Deposits ◽  
Geological Conditions ◽  
Rapid Pressure

How to quickly eliminate outburst in long-distance through-coal seam tunnels is one of the major challenges faced by the tunnel industry in mountainous areas. Compared with coal mine rock crosscut coal uncovering, the work surrounding the rock of through-coal seam tunnels has a high degree of breakage, large cross-section of coal uncovering, and tight time and space. In this paper, a method of networked slotting in long-distance through-coal seam tunnels for rapid pressure relief and outburst elimination is proposed. Based on this method, the corresponding mathematical governing equations and numerical simulation models have been established. The optimal borehole arrangement spacing and the slot arrangement spacing obtained by numerical optimization are 2.85 m and 3.1 m, respectively. Field gas production data of through-coal seam tunnels show that compared with the traditional dense-borehole gas extraction, the method of networked slotting in long-distance through-coal seam tunnels for rapid pressure relief and outburst elimination can shorten the extraction time by about 66%, the net quantity of peak extraction is increased by 3.55 times, and the total quantity of gas extraction when reaching the outburst prevention index is increased by 1.26 times, which verifies the feasibility of this method and the reliability of numerical simulation results. This study could be used as a valuable example for other coal deposits being mined under similar geological conditions.

Experimental Study on Deep Borehole Pre-Cracking Blasting of Drilling through Strata at Low Permeability Seam

2013 ◽  
Vol 868 ◽  
pp. 339-342
Author(s):  
Jian Liu ◽  
Qian Le
Keyword(s):  
Coal Seam ◽  
Control Area ◽  
Low Permeability ◽  
Gas Extraction ◽  
Test Results ◽  
Deep Borehole ◽  
Coal Seam Gas ◽  
Gas Concentration ◽  
Working Face ◽  
Outburst Coal Seam

In the process of roadway excavation in the low permeability outburst coal seam, with drilling through strata in the bottom drainage roadway extracting coal seam gas of control area. In order to improve extraction effect, the method that deep borehole pre-cracking blasting is used to increase the permeability of coal in the drilling through strata seam segment is proposed. The calculation formula on crushing circle and crack circle radius of deep borehole pre-cracking blasting are derived, and the effective loosening radius of blasting is calculated in theory, the research achievements are applied to field test, the test results show that deep borehole pre-cracking blasting permeability improvement technology is carried out in the drilling through strata of the low permeability outburst coal seam, the permeability of coal seam is improved by 180 times, the gas extraction scalar is raised by 8-10 tomes, during the process of roadway excavation, gas concentration of the working face is 0.2%-0.3%, and tunneling footage is increased by 2 times.

scholarly journals Research and Application of Hydraulic Punching Pressure Relief Antireflection Mechanism in Deep “Three-Soft” Outburst Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Beifang Gu ◽  
Yanling Wu
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Technical Problems ◽  
Soft Coal ◽  
Coal Rock ◽  
Outburst Coal Seam ◽  
Soft Coal Seam

To solve the problems of gas predrainage in deep seams with “three softs” and low-air permeability, hydraulic punching pressure relief antireflection technology is proposed on the basis of the research background of gas predrainage technology in Lugou Mine to alleviate technical problems, such as low gas drainage efficiency, in this mine. Through the analysis of the mechanism of hydraulic punching and coal breaking, combined with FLAC3D software, a hydraulic punching pressure relief antireflection model is established. Then, the fracture radii of coal rock are simulated and calculated. The results show that, under hydraulic punching with a water pressure of 10 MPa and coal outputs of 3 m3, 6 m3, 9 m3, and 12 m3, the fracture radii of coal and rock are 3.4 m, 4.8 m, 5.5 m, and 5.9 m, respectively. Using the software to fit the relationship between coal output V and hydraulic punching fracture radius R under the same water pressure, R = 2.32479 V0.3839 is obtained. The field test is carried out in the bottom drainage roadway of 32141 in Lugou Mine. The application effect is as follows: the gas concentration of hydraulic punching with a coal output of 3 m3 is twice that of ordinary drilling, and the coal output of hydraulic punching with a coal output of 6 m3 is four times that of ordinary drilling. The extraction concentration is four times that of ordinary drilling, and the extraction concentration of hydraulic punching with a coal output of 9 m3 is 6.4 times that of ordinary drilling. Combining the results of the numerical simulation and taking into account the actual construction situation on site, the coal output of water jetting from the borehole is 9 m3, and the fracture radius is 5.5 m. This outcome means that the effective half radius is 5.5 m, and the borehole spacing is 7.7 m. These values are the construction parameters for large-scale applications. This proposal provides effective technology and equipment for gas drainage in the deep three-soft coal seam. Consequently, it has promotion and reference significance for gas drainage in coal seam of the same geological type.

scholarly journals Stability Analysis and Protection Measures of Large Section Tunnel in Coal Rich Weak Rock Stratum

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guannan Zhou ◽  
Zijiang Zhao ◽  
Zhanping Song ◽  
Hongjian Wang
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Weak Rock ◽  
Large Section ◽  
Tunnel Face ◽  
Finite Element Software ◽  
Geological Conditions

Due to poor engineering geological conditions of Liujiazhuang tunnel on Shanghai-Kunming Passenger Dedicated Line, the large deformation of weak rock occurs repeatedly during tunnel construction. In this paper, the large-scale finite element software ABAQUS is used to simulate the construction process of a large-section tunnel in weak surrounding rock. It is found that when tunnel face passes through the coal seam, the displacement and stress simulated by the bench method increase abruptly. The maximum stress reaches up to 18 MPa, and displacement reaches 45 mm, which is about twice when without crossing coal seam. It is technically feasible to use the bench method for tunnel construction, under the condition when large settlements is allowed; additionally, the bench method has better technical and economic benefits than that of the CD method. Through the comparative analysis of onsite monitoring data and numerical simulation results, it can be seen that the tunnel is in a dangerous state when passing through the coal seam and measures such as strengthening support or auxiliary advance support should be taken immediately to control the surrounding rock and to ensure tunnel construction safety.

Stress Shell Mechanical Mechanism of Fully-Mechanized Face Enhancing the Upper Limit for Coal Mining and Risk Analysis of Support Break-Off

2012 ◽  
Vol 524-527 ◽  
pp. 466-470
Author(s):  
Jun Ling Hou ◽  
Yan Sun
Keyword(s):  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mining ◽  
Surrounding Rock ◽  
Mechanical Environment ◽  
Upper Limit ◽  
Working Face ◽  
Distribution Rule ◽  
Geological Conditions ◽  
Mining Face

Based on the geological conditions and specific mining technology conditions of the 11014 mining face of Panbei mine in HuaiNan mining group ,using the FLAC3D software, simulate the stress distribution rule and disruption field distribution rule of surrounding rock of Fully-Mechanized face enhancing the upper limit for coal mining along the tendency and trend of coal seam by different mining speed of 6 m/d, 4 m/d and 2 m/d. draw the conclusion that enhancing the mining speed can alleviate the pressure of the working face ,improve the working face mechanical environment,and reduce the extent of the failure field.It provides the theory basis and reference for Fully-Mechanized face enhancing the upper limit for coal mining under similar conditions.

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