Parameter Optimization and Numerical Analysis of the Special Soft Coal Seam Roadway with Large Inclination Dip

Mechanized mining of Longwall top coal caving mining method was used in 1201 work face of thick soft coal seam in Du Jiacun Mine. The face is back to the wind drift along the seam floor excavation, transport drift along the seam roof boring the two crossheading basic fullcoal roadway, due to the relatively soft coal body, joints fractured, coal strength is low, and the coal-rock inclination, roadway section, the weakness of the surrounding rock rock, resulting in the excavation and support difficulties. This chapter based on numerical computation FLAC3D large-scale numerical analysis software, on the inclination special soft coal seam using a different roadway, support method, numerical simulation analysis of the support parameters, the contrast in different roadway support system support parameters, the deformation of surrounding rock displacement, stress distribution, the distribution of plastic zone, the big dip is extremely soft for Du Village coal mine mining Gateway support programs, and through on-site ground pressure observation of program verification.

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

Shock and Vibration ◽

10.1155/2021/7241538 ◽

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.

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Surrounding rock deformation control of asymmetrical roadway in deep three-soft coal seam: a case study

Journal of Geophysics and Engineering ◽

10.1088/1742-2140/aabb2a ◽

2018 ◽

Vol 15 (5) ◽

pp. 1917-1928 ◽

Cited By ~ 10

Author(s):

Wei Zhang ◽

Ziming He ◽

Dongsheng Zhang ◽

Dahong Qi ◽

Weisheng Zhang

Keyword(s):

Coal Seam ◽

Surrounding Rock ◽

Rock Deformation ◽

Deformation Control ◽

Soft Coal ◽

Soft Coal Seam ◽

Surrounding Rock Deformation

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Theory and Application of Gob-Side Entry Retaining in Thick Three-Soft Coal Seam

Geofluids ◽

10.1155/2021/6157174 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Junchao Shen ◽

Ying Zhang

Keyword(s):

Coal Seam ◽

Engineering Practice ◽

Coal Seams ◽

High Resource ◽

Soft Coal ◽

Geological Conditions ◽

Body Construction ◽

Roadway Support ◽

Soft Coal Seam ◽

Engineering Scheme

With the characteristic of less roadway excavation and high resource recovery, gob-side entry retaining (GER) technology is a safe and efficient green mining technology. Many experts and scholars have done extensive research on its principle and application. However, GERs are rarely used in thick soft coal seams. In this paper, based on the geological conditions of a coal mine in China, we propose a novelty approach of GER in thick three-soft coal seam (it means a single seam with a soft roof and a soft floor). The engineering scheme includes roadway expansion, large section roadway support, cutting roof to relieve pressure, and road-inside backfill body construction. The established mechanical and numerical calculation models effectively guide the engineering practice. Field observations showed that all the processes met the requirements of field production. The research results could provide theoretical guidance for the application of GER under similar geological conditions.

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Roadway Support in Deep “Three-Soft” Coal Seam: A Case Study in Yili Mining Area, China

Shock and Vibration ◽

10.1155/2021/8851057 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Wenxin Li ◽

Jinxiao Liu ◽

Lianjun Chen ◽

Zhilu Zhong ◽

Yongle Liu

Keyword(s):

Coal Seam ◽

Large Deformation ◽

Mechanical Test ◽

Mining Area ◽

Surrounding Rock ◽

Rock Properties ◽

Support Design ◽

Soft Coal ◽

Secondary Support ◽

Soft Coal Seam

This paper analyzes the large deformation of roadway in three-soft coal seam under the influence of tectonic stress. Taking the auxiliary conveying uphill roadway in Yili No. 1 Coal Mine as the engineering background, the deformation and failure mechanism of the surrounding rock and the supporting technology were studied. First, the characteristics of stress field and the surrounding rock properties of deep mining area were investigated through geostress measurement and rock mechanical test. Then, the roadway deformation and the loose circle of the supporting structure were obtained. Based on the results from measurement and theoretical analysis, we proposed a concept, i.e., “Stress adjustment-Strengthening-Grouting-Secondary support.” A numerical model was established to analyze the stress distribution and the state of plasticity in the surrounding rock. According to the results of the geostress measurement and the numerical simulation, a combined support scheme was proposed, i.e., “Yielding bolt & Shotcreting” as the primary support and “Prestressed grouting anchor cable & U-shaped shed” as the secondary support. Finally, the underground practice showed that the proposed support scheme can effectively control the large deformation and maintain the long-term stability of the roadway in deep and three-soft coal seam. The proposed technology has guiding significance for the support design under similar mining conditions.

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The Complex Function Method Roadway Section Design of the Soft Coal Seam

Mathematical Problems in Engineering ◽

10.1155/2016/9291412 ◽

2016 ◽

Vol 2016 ◽

pp. 1-12

Author(s):

Shihao Tu ◽

Zhaoxin Li ◽

Zhiwei Ye ◽

Cun Zhang ◽

Lei Zhang

Keyword(s):

Coal Seam ◽

Function Method ◽

Vertical Wall ◽

Complex Function ◽

Surrounding Rock ◽

Type Steel ◽

Soft Coal ◽

Distribution Laws ◽

Soft Coal Seam ◽

Complex Function Method

As for the sophisticated advanced support technique of vertical wall semicircle arch roadway in the three-soft coal seam, a design of flat top U-shape roadway section was put forward. Based on the complex function method, the surrounding rock displacement and stress distribution laws both of vertical wall semicircle arch roadway and of flat top U-shape roadway were obtained. The results showed that the displacement distribution laws in the edge of roadway surrounding rock were similar between the two different roadways and the area of plasticity proportion of flat top U-shape roadway approximately equals that of vertical wall semicircle arch roadway. Based on finite element method, the bearing behaviors of the U-type steel support under the interaction of surrounding rock in vertical wall semicircle arch roadway and flat top U-shape roadway were analyzed. The results showed that, from a mechanics perspective, U-type steel support can fulfill the requirement of surrounding rock supporting in flat top U-shape roadway and vertical wall semicircle arch roadway. The field measurement of mining roadway surrounding rock displacement in Zouzhuang coal mine working face 3204 verified the accuracy of theoretical analysis and numerical simulation.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1049-1050.335 ◽

2014 ◽

Vol 1049-1050 ◽

pp. 335-338 ◽

Cited By ~ 1

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.

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Permeability Enhancement Properties of High-Pressure Abrasive Water Jet Flushing and Its Application in a Soft Coal Seam

Frontiers in Energy Research ◽

10.3389/fenrg.2021.679623 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xinzhe Zhang ◽

Piotr Wiśniewski ◽

Sławomir Dykas ◽

Guojie Zhang

Keyword(s):

High Pressure ◽

Coal Seam ◽

Water Jet ◽

Gas Pressure ◽

Theory And Practice ◽

Abrasive Water Jet ◽

Gas Drainage ◽

Permeability Enhancement ◽

Soft Coal ◽

Soft Coal Seam

High-pressure abrasive water jet flushing (HPAWJF) is an effective method used to improve coal seam permeability. In this study, based on the theories of gas flow and coal deformation, a coupled gas-rock model is established to investigate realistic failure processes by introducing equations for the evolution of mesoscopic element damage along with coal mass deformation. Numerical simulation of the failure and pressure relief processes is carried out under different coal seam permeability and flushing length conditions. Distributions of the seepage and gas pressure fields of the realistic failure process are analyzed. The effects of flushing permeability enhancement in a soft coal seam on the gas drainage from boreholes are revealed by conducting a field experiment. Conclusions can be extracted that the gas pressure of the slotted soft coal seam is reduced and that the gas drainage volume is three times higher than that of a conventional borehole. Field tests demonstrate that the gas drainage effect of the soft coal seam is significantly improved and that tunneling speed is nearly doubled. The results obtained from this study can provide guidance to gas drainage in soft coal seams regarding the theory and practice application of the HPAWJF method.

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

Shock and Vibration ◽

10.1155/2021/2404218 ◽

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.

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