scholarly journals Mine Pressure Behavior Characteristics and Control Methods of a Reused Entry that Was Formed by Roof Cutting: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yajun Wang ◽  
Haosen Wang ◽  
Manchao He ◽  
Qi Wang ◽  
Yafei Qiao ◽  
...  
Keyword(s):  
Deformation Zone ◽  
Dynamic Pressure ◽  
Field Application ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Stress Increase ◽  
Severe Deformation ◽  
Working Face ◽  
Roof Deformation

Noncoal pillar mining with automatic formation of a roadway is a new coal mining method that is tailored to improve the coal resource recovery rate and reduce the investment in roadway tunneling. Using this proposed method, a reuse entry is formed by roof cutting instead of tunneling. In this paper, the S1201-II working face of the Ningtiaota Coal Mine was used as a case study. The stress distribution of surrounding rock and the roof deformation characteristics of the reused entry during the mining process of the second working face were studied through FLAC3D numerical simulations combined with field measurements. The results indicate that the zone close to the reused entry led to higher stress in advance. If this stress is superimposed with the lateral pressure of the adjacent mined working face, it will be more difficult to maintain the reused entry. In the engineering case study described here, the reused entry created a stress increase zone and a severe deformation zone in the range of 0–80 m in front of the working face, and its range was approximately 37.5% larger than an ordinary entry. The stress peak in the stress increase zone increased by approximately 34.7% over that of an ordinary entry. The maximum amount of deformation within the severe deformation zone increased by 94.4% over that of an ordinary entry. To properly control the surrounding rock stress and deformation of the reused entry, a dynamic pressure bearing support in front of the working face with adaptability to the large roof deformation and high support strength is proposed here. Field application results showed that the final roof deformation with the dynamic pressure bearing support can be satisfactorily controlled within 110∼130 mm. These findings can provide a reference for researchers and field engineering technicians when engaging in the support work of reused entry.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals Control of Gob-Side Roadway with Large Mining Height in Inclined Thick Coal Seam: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xie Fuxing
Keyword(s):  
Numerical Simulation ◽  
Coal Pillar ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Thick Coal Seam ◽  
Working Face ◽  
Rock Structure ◽  
Large Mining Height ◽  
Mining Height

The gob-side roadway of 130205, a large-mining-height working face in the Yangchangwan coal mine, was investigated in terms of the mine pressure law and support technology for large mining heights and narrow coal pillars for mining roadways. The research included field investigations, theoretical analysis, numerical simulation, field tests, and other methods. This paper analyzes the form of movement for overlying rock structure in a gob-side entry with a large mining height and summarizes the stress state and deformation failure characteristics of the surrounding rock. The failure mechanism of the surrounding rock of the gob-side roadway and controllable engineering factors causing deformation were analyzed. FLAC3D numerical simulation software was used to explore the influence law of coal pillar width, working face mining height, and mining intensity on the stability of the surrounding rock of the gob-side roadway. Ensuring the integrity of the coal pillar, improving the coordination of the system, and using asymmetric support structures as the core support concept are proposed. A reasonably designed support scheme for the gob-side roadway of the working face for 130205 was conducted, and a desirable engineering effect was obtained through field practice verification.

Study of the Trellis Support of Working Face Roadway in Impact Coal Seam

2014 ◽  
Vol 941-944 ◽  
pp. 2558-2564
Author(s):  
Yu Kai Lv ◽  
Cong Jiang ◽  
Yao Dong Jiang
Keyword(s):  
In Situ Stress ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Working Face ◽  
Coal Bumps ◽  
Roadway Support ◽  
The Stability ◽  
The Impact ◽  
Physical And Mechanical Characteristics

Coal bumps happened many times in mining at No.5 seam of Tangshan coal mine. Strengthen the roadway’s support of working face can effectively reduce disaster losses. With the research background of the 3654 working face, the mine pressure monitoring for the existing support form of roadway has been carried on. Perform a numerical simulation for the original roadway support, base on the in-situ stress and physical and mechanical characteristics of surrounding rock in experimental; study the impact of the stability of roadway’s surrounding rock, while the space change of trellis and change of supporting intensity; optimizing the original support form, so as to maximum reducing the impact of the coal bumps.

scholarly journals Research and Application of Directional Roof Cutting and Pressure Releasing Technology for Retracement Channel of 3314 Working Face in Hexi Coal Mine

2021 ◽  
Author(s):  
Jindong Cao ◽  
Xiaojie Yang ◽  
Ruifeng Huang ◽  
Qiang Fu ◽  
Yubing Gao
Keyword(s):  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Mine Pressure ◽  
Working Face ◽  
Geological Conditions ◽  
Cutting Effect ◽  
The Stability ◽  
Two Sides

Abstract The high stress of the surrounding rock of Hexi Coal Mine easily leads to severe deformation of the retracement channel and the appearance of the mine pressure during the retreat severely affects the stability of the roadway. In order to solve the above problems, a roadway surrounding rock control technology is proposed and tested. The bidirectional energy-concentrated tensile blasting technology is used to perform directional cutting to cut off the stress propagation path. Firstly, the deformation mechanism of the roof is analyzed by establishing the deformation mechanical model of the roof of the retracement channel. Then, according to the geological conditions of working face 3314 and theoretical calculation, the key parameters of roof cutting and pressure releasing of retracement channel are determined, and through the numerical analysis of its cutting effect, the length of cutting seam is 11.5m, and the cutting angle is 10°. Finally, a field test is carried out on the retracement channel of 3314 working face to verify the effect of roof cutting. The results show that the deformation of the retracement channel and the main roadway is very small. In the process of connecting the working face and the retracement channel, the maximum roof to floor convergence is 141mm, and the two sides convergence is 79mm. After the hydraulic support was retracted, the maximum roof to floor convergence of the surrounding rock is 37 mm, and the two sides convergence is 33mm. The roof cutting and pressure releasing of the retracement channel ensures the safe evacuation of the equipment and the stability of the main roadway. The cutting effect is obvious for the release of pressure, which is of great significance to engineering practice.

Study on Mine Pressure Behavior of Roadway in Highly Irregular Working Face in Daizhuang Coal Mine

2012 ◽  
Vol 256-259 ◽  
pp. 1443-1446
Author(s):  
Xing Lin Wen ◽  
Lin Hai Gao ◽  
Chuan Lei Li ◽  
Meng Meng Dong
Keyword(s):  
Coal Mine ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Mining Engineering ◽  
Deformation Characteristics ◽  
Working Face ◽  
Production Safety ◽  
Support Force ◽  
Mining Face ◽  
Important Significance

The irregular face mechanized mining is one of the difficult problems in the field of mining engineering. In this thesis, the roadways of 4324 extremely irregular face in DaiZhuang Mine were taken as research object. Through on-site mine pressure observation, the deformation characteristics of the surrounding rock and support force was analyzed. Next the mine pressure appeared rule of the roadways was study. This study benefited that the production of 4324 mining face went on wheels, at the same time, it had important significance to production safety of irregular working face with similar conditions.

Analysis on Instability of Surrounding Rock in Gob-Side Entry Retaining with the Character of Soft Rock Composite Roof

2012 ◽  
Vol 524-527 ◽  
pp. 396-403 ◽  
Author(s):  
De Chuan Yang ◽  
Ming Zhong Gao ◽  
Yun Hai Cheng ◽  
Wu Sheng ◽  
Jia Sheng Chen
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Main Roof ◽  
Wide Distribution ◽  
Economic Security ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Working Face ◽  
Immediate Roof ◽  
Plastic Zones

The filling belt of gob-side entry retaining with the character of soft rock composite roof,deforms violently,affected by the fracture and rotation of the main roof,and is prone to instability.This essay,considering characteristecs of coal mine pressure behavior on -790m 1311 (1) working face ventilation roadway at DingJi coal mine in HuaiNan,puts forward structural mech -anics model of the key block of gob-side entry retaining,which is used to forecast the position of the fracture line of the main roof, and analyze the roof subsidence at the side of the filling belt;It applies FLAC and UDEC to simulate distribution of plastic zones of surrounding rock of gob-side entry retaining,and stress variation law of the immediate roof and the main roof along coal seam inclination.The results show that:stress concentration factor of the immediate roof on the filling belt is about 1.6,first decreasing and then increasing with increasing width of the filling belt,which indicates that reasonable width of the filling belt is 3.0 m in accordance with the requirement of economic security requirment. The filling belt has significantly wide distribution of the plastic zones,with its four corners obviously plasticized,and overlying strata above the filling belt at side of goaf suffering upward plasticization,which is the result of rotation of the main roof; Deform- ation instability of filling belt is mainly caused by fracture rotation of the main roof;Finally, the measures to reduce the instability of gob-side entry retaining with the character of soft rock comp- osite roof are put forward.

scholarly journals Gob-Side Entry Retained with Soft Roof, Floor, and Seam in Thin Coal Seams: A Case Study

2020 ◽  
Vol 12 (3) ◽  
pp. 1197 ◽  
Author(s):  
Zhijun Tian ◽  
Zizheng Zhang ◽  
Min Deng ◽  
Shuai Yan ◽  
Jianbiao Bai
Keyword(s):  
Mining Industry ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Mine Pressure ◽  
Coal Seams ◽  
Rock Stability ◽  
Working Face ◽  
Geological Conditions ◽  
Surrounding Rock Control

Gob-side entry retained technology is of great significance to develop coal mining industry sustainably, which can improve the coal recovery rate by mining without the coal pillar. However, scholars and researchers pay little attention to the gob-side entry retained with soft roof, floor, and seam in thin coal seams. In this study, the difficulties and key points of surrounding rock control for gob-side entry retained with soft roof, floor, and seam in thin coal seams were firstly proposed. Secondly, the mechanical model of the interaction between the roadside backfill body and the roof for gob-side entry retained with soft roof, floor, and seam in thin coal seams was established, and the relevant parameters were designed. Finally, the above results were verified by the engineering practice of gob-side entry retained technology and the monitoring of mine pressure on the 1103 working face of the Heilong Coal Mine. Moreover, the effect factors of surrounding rock stability for gob-side entry retained with soft roof, floor, and seam in thin coal seams were discussed using the discrete element method. The results could provide guidance for gob-side entry retained with soft roof, floor, and seam in thin coal seams under similar geological conditions.

scholarly journals Failure Analysis of a Pre-Excavation Double Equipment Withdrawal Channel and Its Control Techniques

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6368
Author(s):  
Chen Li ◽  
Xiaofei Guo ◽  
Xiaoyong Lian ◽  
Nianjie Ma
Keyword(s):  
Numerical Simulation ◽  
Failure Modes ◽  
Abutment Pressure ◽  
Dynamic Pressure ◽  
Stability Control ◽  
Field Application ◽  
Surrounding Rock ◽  
Control Technique ◽  
Mining Equipment ◽  
Double Row

The use of pre-excavation equipment withdrawal channels (EWCs) at the stop-production line is important for the rapid withdrawal of coal mining equipment. However, during the final mining period, the dynamic pressure of a pre-excavated double EWC is severe, which leads to instability of the surrounding rock around the EWCs. Therefore, in this paper, the methods of field monitoring, theoretical analysis, and numerical simulation were used to systematically study the stress and plastic zone evolution of a double EWC during the final mining period. Firstly, the distribution characteristics of mining abutment pressure and roadway failure modes under the action of mining abutment pressure were analyzed theoretically. Afterward, a FLAC3D mining numerical model was established according to the distribution of rock strata obtained from roof detection. Finally, the evolution laws of the stress fields and plastic zones of the EWCs during final mining were obtained by numerical simulation. The present study suggests that asymmetric stress distribution dominates asymmetric failure of the surrounding rock around the EWCs during the final mining period, and deformation failure within 10 m from the working face to the main EWC (MEWC) accounted for most of the roadway deformation. Based on the research results combined with actual production experience, the stability control technique of the surrounding rock with reinforcement of anchor cables and double-row buttress hydraulic support for the MEWC was put forward. After the field application, the ideal result was obtained.

scholarly journals Stabilization of Rock Roadway under Obliquely Straddle Working Face

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5759
Author(s):  
Peng Wang ◽  
Nong Zhang ◽  
Jiaguang Kan ◽  
Bin Wang ◽  
Xingliang Xu
Keyword(s):  
Dynamic Pressure ◽  
Stability Control ◽  
Surrounding Rock ◽  
Horizontal Distance ◽  
Floor Rock ◽  
Rock Stability ◽  
Ground Pressure ◽  
Working Face ◽  
Rock Roadway

A floor rock roadway under an oblique straddle working face is a typical dynamic pressure roadway. Under the complex disturbance of excavation engineering works, the roadway often undergoes stress concentration and severe deformation and damage. To solve the problem of surrounding rock stability control for this roadway type, this study considered the East Forth main transport roadway in the floor strata of the 1762(3) working face of the Pansan coal mine. In situ ground pressure monitoring and numerical simulation calculation using the FLAC2D software were carried out. The influence laws of the surrounding rock lithology, the vertical and horizontal distance between the roadway and overlying working face, the positional relationship between the roadway and the overlying working face, and the support form and strength of the rock surrounding an oblique straddle roadway were obtained. Within the range of mining influence, the properties of the rock surrounding the roof and floor were very different, and the deformation of the rock surrounding the two sides exhibited regional difference. The influence range of the mining working face on the rock floor of the roadway was approximately 30–40 m, and that of horizontal mining was approximately 50–60 m. The mining influence on the rock surrounding the side roadway of the working face is large, but the mining influence on the roadway below is small. Using FLAC2D, the stress and displacement characteristics of the rock surrounding the obliquely straddle roadway were compared and analyzed when the bolt support, combined bolt and shed support, and bolt–shotcreting–grouting support were adopted, the proposed support scheme of bolting and shotcreting was successfully applied. The deformation of the rock surrounding the roadway was satisfactorily controlled, and the results were useful as a reference for similar roadway maintenance projects.

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