scholarly journals Study on Intelligent Identification Method of Coal Pillar Stability in Fully Mechanized Caving Face of Thick Coal Seam

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 305 ◽  
Author(s):  
Jingjing Dai ◽  
Pengfei Shan ◽  
Qi Zhou
Keyword(s):  
Coal Seam ◽  
Simulation Experiment ◽  
Coal Pillar ◽  
Shanxi Province ◽  
Parameter Determination ◽  
Pillar Stability ◽  
Thick Coal Seam ◽  
Identification Method ◽  
Optimal Value ◽  
The Relationship

The combination of coal precise mining and information technology in the new century is one of the important directions for the future development of coal mining. Taking the fully mechanized top coal caving condition of a thick coal seam in the 90,101 working face of Baoshan Yujing Coal Mine in Shanyin City, Shanxi Province as an example, the intelligent identification method of section coal pillar stability was studied. The load transfer law of overlying strata in the upper part of coal pillar was analyzed, and the coal pillar values of each index were obtained by using an empirical formula, mean impact value-genetic algorithm-BP neural network (MIV-GA-BP) simulation experiment, and finite difference algorithm. The Delphi index evaluation system was used to calculate the optimal value of the coal pillar. The results showed that the non-contact cantilevered triangle on the two wings of the coal pillar in the goaf reduced the stress on the coal pillar; according to the width of the coal pillar at 10 m, 14 m, 16 m, and 20 m, combined with the relationship between the plastic zone and the core zone of coal pillar, and the relationship between the stress field and the ultimate strength of coal pillar, the numerical simulation value of the coal pillar was determined. The MIV (mean impact value) characteristics screened out the influencing factors of coal pillar width in the section near the horizontal fully mechanized top coal caving face order of importance; the relative error between the predicted value and the expected value of the MIV-GA-BP simulation experiment was less than 5%, which has good stability for the multi-factor nonlinear coupling prediction problem; and the optimal value of the coal pillar was 16.03 m by the intelligent identification method of the coal pillar. When the 16 m pillar was used, the surrounding rock deformation of the roadway was small, and the control effect was good. The research results provide a theoretical basis and reference for the parameter determination of similar projects.

scholarly journals Study on Rib Sloughage Prevention Based on Geological Structure Exploration and Deep Borehole Grouting in Front Abutment Zones

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Cheng Wang ◽  
Zuqiang Xiong ◽  
Chun Wang ◽  
Yuli Wang ◽  
Yaohui Zhang
Keyword(s):  
Coal Seam ◽  
Tectonic Stress ◽  
Geological Structure ◽  
Longwall Face ◽  
Mine Safety ◽  
Shanxi Province ◽  
Thick Coal Seam ◽  
Plastic Failure ◽  
Mining Conditions ◽  
Roof Strata

This research presents the grouting method of preventing rib sloughage which severely impacts mine safety and longwall retreat speed in thick coal seam with numerical simulation and laboratory tests. Based on the analysis of the plastic failure mode of five types of coal seam, roof strata ahead of the longwall face, and fractures developed in the coal seam, the following results are drawn, the range and degree of plastic failure generated in the coal seam and roof strata ahead of the longwall face gradually decreased as the coal mass strength increased; the grouting boreholes are essentially laid out within the coal rib instead of the roof. For a particular case of a coal mine in Shanxi province, a novel cement-based material was grouted, which fulfilled the reinforcement requirements under the tectonic stress regions and front abutment zones. Besides, the grouting borehole construction requested predrilled boreholes, full borehole intubation, lengthened hole sealing, and multiple-step drilling and grouting. This study can provide a theoretical framework of a design overview and practical basis for similar mining conditions in other coalfields.

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 Cutting-Caving Ratio Optimization of Fully Mechanized Caving Mining with Large Mining Height of Extremely Thick Coal Seam

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Kai Wang ◽  
Tong Zhao ◽  
Kaan Yetilmezsoy ◽  
Xiaoqiang Zhang
Keyword(s):  
Coal Seam ◽  
Influencing Factors ◽  
Recovery Rate ◽  
Engineering Application ◽  
Thick Coal Seam ◽  
Coal Wall ◽  
Large Mining Height ◽  
Cutting Height ◽  
The Relationship ◽  
Mining Height

Serious rib spalling and low recovery rate problems caused by the poor top-coal caving property (TCCP) were investigated in fully mechanized caving mining with large mining height (FMCMLMH) of extremely thick coal seam. For this aim, theoretical calculation, numerical simulation, and engineering application were applied to study the reasonable cutting-caving ratio under the influence of different factors. The calculation formula of reasonable cutting height in FMCMLMH was obtained, and effective factors were determined. Moreover, Ft (the top-coal yield failure coefficient) and Fw (the coal wall yield failure coefficient) were defined, and each factor was fitted by using a linear regression equation. The minimum Ft of fully fractured top coal was 0.6, and the main influencing factors were buried depth and Protodyakonov coefficient. The maximum Fw of the stable coal wall was 1.5, and the main influencing factors were buried depth and cutting height. According to the relationship between coal wall stability and recovery rate, the relationship between coal seam strength and top-coal thickness at different cutting heights was obtained, and the mining zone was divided into four subzones. Engineering application showed that the optimal cutting height of Xiegou Coal Mine was 4 m, the cutting-caving ratio was 1 : 2.75, and the recovery rate could reach more than 85%, which was the most reasonable.

scholarly journals Thermal infrared characteristics of rock strata fracture in steeply inclined and extra thick coal seam

2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 3933-3940
Author(s):  
Yan-Bin Yang ◽  
Feng Cui
Keyword(s):  
Coal Seam ◽  
Infrared Radiation ◽  
Thermal Infrared ◽  
Horizontal Section ◽  
Thick Coal Seam ◽  
Mining Depth ◽  
Movement Rules ◽  
The Relationship ◽  
Thermal Infrared Radiation ◽  
Rock Strata

In view of the complexity of the rules of rock strata fracture in steeply inclined and extra thick coal seam, the mining method of horizontal section top coal caving was put forward. In this paper, the physical similarity simulation model is established to analyze the movement rules of rock strata. The relationship between the form of rock strata fracture and the thermal infrared radiation is analyzed according to studying the characteristics of the thermal infrared radiation temperature of the rock strata fracture. Meanwhile, the changes characteristics of abnormal area of thermal infrared radiation were mastered, and the precursors of thermal infrared radiation of rock strata fracture were predicted. The results showed that the rock strata fracture form of steeply inclined and extra thick coal seam is related to the mining depth.

Elastic-Plastic Mechanics Analysis on Stability of Coal Pillar

2008 ◽  
Vol 33-37 ◽  
pp. 1123-1128 ◽  
Author(s):  
Wei Gao
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
New Method ◽  
Engineering Practice ◽  
Strip Mining ◽  
Mining Engineering ◽  
Pillar Stability ◽  
Elastic Plastic ◽  
Equilibrium Method ◽  
Mechanics Analysis

Because it is very important to study the coal pillar stability, a lot of methods to do this have been proposed. But most of those methods do not consider the nature of coal material and only study the coal pillar that is level. To solve this problem suitably, here a new method is proposed. In this method, the plastic softening nature of coal material is considered. And also, the coal seam pitch is considered in our analysis. Based on real deformation of coal pillar and the previous study, the limiting equilibrium method is applied. At last, the rationality of our method is verified through a strip mining engineering example. And the results show that, the computing results of our method are coincided with measuring results very well and our method can be applied in real engineering practice very well.

scholarly journals Numerical Investigation on the Ground Response of a Gob-Side Entry in an Extra-Thick Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
C.W. Zang ◽  
G.C. Zhang ◽  
G.Z. Tao ◽  
H.M. Zhu ◽  
Y. Li ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Numerical Investigation ◽  
Large Scale ◽  
Shear Failure ◽  
Coal Pillar ◽  
Coal Mass ◽  
Thick Coal Seam ◽  
Anchor Cable ◽  
Study Results

This study was aimed at the large deformation phenomenon of rock mass surrounding the gob-side entry driven in a 20 m extra-thick coal seam. Taking tailgate 8211 as the engineering background, a numerical investigation was employed to analyze the deformation law of the gob-side entry. The study results are as follows. (1) Because the immediate roof was composed of weak coal mass with a thickness of 17 m, the roof coal mass was vulnerable to fail with the effect of overlying strata pressure; thus, a visual subsidence of roof coal mass with a maximum convergence of 800 mm was observed in the field. (2) The bearing capacity of the coal pillar was significantly less than that of the panel rib, resulting in the pillar failing more easily under the ground pressure and then generating large-scale squeezing deformation. (3) The roof and panel rib were in a state of shear failure with a failure depth of about 5 m. The coal pillar was entirely in a state of plastic failure. (4) A support scheme including an asymmetric anchor beam truss, roof angle anchor cable, and anchor cable combination structure was proposed. The field work confirmed that this support scheme could efficiently control the deformation and failure of the rock mass surrounding the gob-side entry. This study provides the theoretical basis and technical support for the control of rocks surrounding the gob-side entry in similar conditions.

scholarly journals The Mechanism and Control Technology of Strong Strata Behavior in Extra-Thick Coal Seam Mining Influenced by Overlying Coal Pillar

2019 ◽  
Vol 11 (1) ◽  
pp. 452-461
Author(s):  
Rui Gao ◽  
Tiejun Kuang ◽  
Yiwen Lan
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
In Situ Monitoring ◽  
Thick Coal Seam ◽  
Maximum Deformation ◽  
Working Face ◽  
Strata Behavior ◽  
Seam Mining ◽  
Roadway Deformation ◽  
And Control

Abstract This work aimed at revealing the mechanism of strong strata behavior in extra-thick coal seam mining which was influenced by an overlying coal pillar (OCP). To this end, the evolution characteristics of the stress and displacement in advance coal body of the working face were studied via numerical simulation. On this basis, the mechanism of strong strata behavior in working face affected by OCP was revealed. In situ monitoring also demonstrated that, as the working face mining near to the position of OCP, severe rib spalling and roadway deformation frequently appeared. The scheme of strengthening the hydraulic supports resistance and adding anchor cables was put forward to control the surrounding rocks in the stope. As a result, the maximum deformation of the roadway height was 0.66m and could completely meet the demands for safe mining. The study on the mechanism of strong strata behavior in working face and the strengthen supporting scheme would provide a theoretical basis for similar mining conditions, thus ensure safe and efficiency coal seam mining.

scholarly journals Determination of Cyclic Filling Length in Gob-Side Entry Retained with Roadside Filling and Its Application

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Zizheng Zhang ◽  
Jinlin Xin ◽  
Jianbiao Bai ◽  
Xianyang Yu ◽  
Weijian Yu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Difference Method ◽  
Suggested Method ◽  
Stress Difference ◽  
Thick Coal Seam ◽  
Mechanics Model ◽  
Working Face ◽  
Geological Conditions ◽  
The Relationship

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 the roadside filling area was established, and 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 the 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 were determined. Combined with the geological conditions of the 1103 thin coal seam working face of Heilong Coal Mine and the 1301 thick coal seam working face of Licun Coal Mine, the suggested method was applied to determine that the rational cyclic filling lengths 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.

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