Assessment of risk tendency of coal bursting pressure in deep outburst seam based on fuzzy evaluation method

2021 ◽  
pp. 1-9
Author(s):  
Beifang Gu ◽  
Minbo Zhang
Keyword(s):  
Coal Seam ◽  
Influencing Factors ◽  
Hierarchical Structure ◽  
Coal Mine ◽  
Bursting Pressure ◽  
Strong Impact ◽  
Structure Model ◽  
Working Face ◽  
The Hierarchical Structure ◽  
Impact Risk

In order to analysis the mechanism of coal bursting pressures of deep coal seams, and take effective methods to identify, monitor and control coal bursting pressure, this study takes 21101 working face of No. 2 Coal seam in Dongpang Coal Mine as an example, risk identification was carried out for the harmful factors of coal bursting pressure in coal seam 21101 in Dongpang Coal Mine, and each influencing factor was classified. The hierarchical structure model of the influencing factors of coal bursting pressure in coal seam protruding deep in Dongpang Coal Mine was established in combination with expert opinions, and the weight of each level index was calculated by MATLAB software. The results show that the 21101 working face of No. 2 coal seam in Dongpang Coal Mine has strong impact risk, and the main risk factors include geological structure, impact resistance of coal and rock, mining stress, inducing factors, emphasis degree of impact risk. According to the hierarchical structure model of the influencing factors, the corresponding safety measures are put forward to prevent the damage caused by coal bursting pressure in advance and ensure the high quality and safe production in the mine. The qualitative and quantitative methods are used to make the evaluation process more reasonable and scientific.

Redundant Repair Mechanism Base on the Hierarchical Structure Model

2010 ◽  
Vol 40-41 ◽  
pp. 257-261
Author(s):  
Zheng Quan Ju ◽  
Liang Yuan ◽  
Meng Hua Man ◽  
Chuang Wer Wang
Keyword(s):  
Hierarchical Structure ◽  
Electronic System ◽  
Structure Model ◽  
Repair Mechanism ◽  
New Thought ◽  
Structure Matrix ◽  
Half Adder ◽  
The Hierarchical Structure

This paper proposed a hierarchical structure model of the electronic system firstly, and then the expression method of the structure matrix was optimized. After that, the repair question of the system with redundant module was analyzed and turned into a kind of matrix solving, and the redundant repairs algorithm was provided at the same time. By repairing one bit half adder with one redundant mould, the feasibility of this method was proved and a new thought for the electronic system repair online was raised.

scholarly journals Determination of cyclic filling length in gob-side entry retained with roadside filling and its application

2020 ◽  
Author(s):  
Zizheng Zhang ◽  
Jianbiao Bai ◽  
Xianyang Yu ◽  
Weijian Yu ◽  
Min Deng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Difference Method ◽  
Suggested Method ◽  
Stress Difference ◽  
Thick Coal Seam ◽  
Mechanics Model ◽  
Working Face ◽  
Geological Conditions ◽  
The Relationship

Abstract Gob-side entry retained with roadside filling (GER-RF) plays a key role in achieving coal mining without pillar and improving the coal resource recovery rate. Since there are few reports on the cyclic filling length of GER-RF, a method based on the stress difference method is proposed to determine the cyclic filling length of GER-RF. Firstly, a stability analysis mechanics model of the immediate roof above roadside filling area in GER was established, then the relationship between the roof stress distribution and the unsupported roof length was obtained by the stress difference method. According to the roof stability above roadside filling area based on the relationship between the roof stress and its tensile strength, the maximum unsupported roof length and rational cyclic filling length of GER-RF. Combined with the geological conditions of the 1103 thin coal seam working face of Heilong Coal Mine and the geological conditions of the 1301 thick coal seam working face of Licun Coal Mine, this suggested method was applied to determine that the rational cyclic filling lengths of GER-RF were 2.4 m and 3.2 m, respectively. Field trial tests show that the suggested method can effectively control the surrounding rock deformation along with rational road-in support and roadside support, and improve the filling and construction speed.

scholarly journals Reasonable Scope of Kilometer Drilling in Lower Layer of Extrathick Coal Seam: A Case Study of Tingnan Coal Mine, China

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Delong Zou ◽  
Xiang Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Lower Layer ◽  
Maximum Depth ◽  
Support Pressure ◽  
Directional Drilling ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Working Face ◽  
Fracture Development

When stratified mining is adopted in high-gas and extrathick coal seam, a large amount of pressure-relief gas of the lower layer flows into the upper layer goaf along the cracks in the layer, resulting in upper layer working face to frequently exceed the gas limit. And ordinary drilling can no longer meet the requirements of the pressure-relief gas drainage of the lower layer. The 205 working face of Tingnan Coal Mine is taken as the test background in this paper, and based on the “pressure-relief and flow-increase” effect of the lower layer under the action of mining stress during the upper layer mining, the gas drainage of kilometer directional drilling in lower layer is studied. According to the distribution characteristics of support pressure before and after the working face, the pressure-relief principle, fracture development characteristics, and gas migration law of the lower layered coal body are analyzed in the process of advancing the upper layered working face in the extrathick coal seam with high gas. The maximum depth of goaf damage is calculated theoretically, and the Flac3D numerical simulation of the failure deformation of the 205 working face floor is carried out. It is found that the maximum depth of plastic failure of the lower layer is about 13 m. According to the plastic deformation of the lower layer under different vertical depths and the movement of coal and rock mass, it is determined that the reasonable range of kilometer directional drilling in the lower layer is 6–9 m below the floor vertical depth. From 15 m to 45 m in the two parallel grooves, there is no fracture failure with a sharp increase or decrease in the displacement in the local range. Meanwhile, in this part, the roof falling behind is not easy to compaction, and the displacement of the floor is large, which does not cause plastic damage. The degree of pressure relief is more sufficient, and the permeability of the lower layer is good. Therefore, drilling should be arranged as much as possible along the working face in this tendency range. The determination of reasonable arrangement range of kilometer directional drilling in extrathick coal seam provides reference index and theoretical guidance for industrial test of working face and also provides new ideas for gas control of stratified mining face in high-gas and extrathick coal seam.

scholarly journals An Application of Hierarchical Structure Model for Trip Mode Choice Forecasting in China

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Zhuping Zhou ◽  
Wei Wang ◽  
Qizhou Hu
Keyword(s):  
Hierarchical Structure ◽  
Urban Form ◽  
Mode Choice ◽  
Structure Model ◽  
Policy Makers ◽  
Mode Split ◽  
Forecasting Method ◽  
The Hierarchical Structure ◽  
Transportation Development ◽  
Relationship Of

Trip mode split is the result of interrelated and mutually independent factors, such as city scale, urban form, economic level, trip distance, and travel time. In order to analyze the formation of traffic structure, it is necessary to make a comprehensive study on the mechanism of these factors and obtain the basic causal relationship of them. Based on this, by using the hierarchical structure model in system engineering, this paper firstly clarifies the logical relationship of different factors. Then, the existing trip survey data of several cities is used to establish the mathematical relationship of various factors of the structure model. Finally, the mode choice forecasting method is proposed based on the structure model of influencing factors. The case study result of six cities shows small bias, indicating that the proposed method is of great practical value. Policy makers can use the results to discover the trip structure feature and grasp the direction of transportation development policy.

scholarly journals Analysis on Rock Burst Risks and Prevention of a 54 m-Wide Coal Pillar for Roadway Protection in a Fully Mechanized Top-Coal Caving Face

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zhihua Li ◽  
Ke Yang ◽  
Jianshuai Ji ◽  
Biao Jiao ◽  
Xiaobing Tian
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Influencing Factors ◽  
Abutment Pressure ◽  
Large Diameter ◽  
Coal Pillar ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Working Face ◽  
Coal Pillars

A case study based on the 401103 fully mechanized caving face in the Hujiahe Coal Mine was carried out in this research to analyze the rock burst risks in a 54 m-wide coal pillar for roadway protection. Influencing factors of rock burst risks on the working face were analyzed. Stress distribution characteristics on the working face of the wide coal pillar for roadway protection were discussed using FLAC3D numerical simulation software. Spatial distribution characteristics of historical impact events on the working face were also investigated using the microseismic monitoring method. Results show that mining depth, geological structure, outburst proneness of coal strata, roof strata structure, adjacent mining area, and mining influence of the current working face are the main influencing factors of rock burst on the working face. Owing to the collaborative effects of front abutment pressure of the working face and lateral abutment pressure in the goaf, the coal pillar is in the ultimate equilibrium state and microseismic events mainly concentrate in places surrounding the coal pillars. Hence, wide coal pillars become the regions with rock burst risks on the working face. The working face adopts some local prevention technologies, such as pressure relief through presplitting blasting in roof, pressure relief through large-diameter pores in coal seam, coal seam water injection, pressure relief through large-diameter pores at bottom corners, and pressure relief through blasting at bottom corners. Moreover, some regional prevention technologies were proposed for narrow coal pillar for roadway protection, including gob-side entry, layer mining, and fully mechanized top-coal caving face with premining top layer.

Research on the Occurrence Mechanism and Evaluation of Coal Mine Accidents

2013 ◽  
Vol 295-298 ◽  
pp. 2889-2892
Author(s):  
Qi Zeng ◽  
Yan Yan Wu
Keyword(s):  
Analytic Hierarchy Process ◽  
Hierarchical Structure ◽  
Coal Mine ◽  
Structure Model ◽  
Analytic Hierarchy ◽  
Main Factors ◽  
Mine Accidents ◽  
Occurrence Mechanism ◽  
Causation Analysis ◽  
Hierarchy Process

Based on the analysis of the coal mine accidents dangerous sources and essential factors of occurrence mechanism, the coal mine accidents causation model is built by combing with system security theory and dangerous sources theory. This paper analyzes a large number of accidents causation factors and screens the main factors; finally the coal mine accidents hierarchical structure model is constructed. What’s more, combined with examples, the fuzzy analytic hierarchy process is applied to evaluate the accidents causation analysis.

scholarly journals Numerical simulation study on gas drainage by interval hydraulic flushing in coal seam working face

2021 ◽  
pp. 014459872110102
Author(s):  
Shengrong Xie ◽  
Junqi Cui ◽  
Dongdong Chen ◽  
Ping Chen
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Coal Mine ◽  
Simulation Software ◽  
Gas Pressure ◽  
Gas Extraction ◽  
Gas Drainage ◽  
Drainage Radius ◽  
Working Face ◽  
Effective Drainage

In order to solve the problem of difficult gas extraction in coal mine, a method of gas extraction from coal seam by interval hydraulic flushing is put forward. Based on the coal seam gas occurrence conditions of 7609 working face in Wuyang Coal Mine, the numerical simulation research on gas drainage by ordinary drilling and hydraulic flushing drilling was carried out by using COMSOL numerical simulation software. The results show that with the increase of hydraulic flushing coal quantity, the effective gas drainage radius also increases. The effective extraction radius of ordinary drilling is 0.5 m, and the effective extraction radius is 1.0 m, 1.2 m and 1.3 m respectively when the coal flushing quantity is 0.5t/m, 1.0t/m and 1.5t/m. As multiple boreholes are drained at the same time, the boreholes will affect each other, which will reduce the gas pressure and increase the effective drainage radius, the spacing between boreholes can be greater than twice the effective drainage radius of a single borehole when arranging boreholes. And the smaller the flushing interval, the more uniform the gas pressure reduction area. According to the numerical simulation results, the ordinary drilling and 1.0t/m interval hydraulic flushing test were carried out in the field. Through observation and analysis, the gas concentration of the interval hydraulic flushing drilling module was increased by 31.2% and the drainage purity was increased by 5.77 times compared with the ordinary drilling module. It shows that the interval hydraulic flushing drilling can effectively improve the gas drainage effect.

Research on Walling-up with Concrete Block Technology of Gob-Side Entry Retaining Based on Fully Mechanized Face in Medium-Thickness Coal Seam

2011 ◽  
Vol 121-126 ◽  
pp. 2878-2882 ◽  
Author(s):  
Hui Li Lin ◽  
Yong Kui Shi
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Concrete Block ◽  
Coal Face ◽  
Medium Thickness ◽  
Working Face ◽  
Immediate Roof ◽  
Wide Lane ◽  
Driving Workload ◽  
Supporting Effect

Gob-side entry retaining is an advanced and green mining technology, which can avoid using pillar and island working face, reduce driving workload, alleviate the tension between extraction and driving, and achieve a Y-type ventilation. The coal mine in this research successfully reserved a 485m roadway in No.10302 fully mechanized coal face by employing wide lane driving, pre-driven roadway, pre-controlling immediate roof in the roadway, and gob-side entry retaining by walling up with multi-standard concrete block using break-joint vertical stacking technology. From doing so, the supporting effect is significant, the roadway is integrated and the stable wall is free of distortion or cracking. This research paves a new way for gob-side entry retaining of fully mechanized mining in China.

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