Stability and Control of Retracement Channels in Thin Seam Working Faces with Soft Roof

Qin, Binbin; He, Fulian; Zhang, Xiaobing; Xu, Xuhui; Wei, Wang; Li, Liang; Dou, Chao

doi:10.1155/2021/8667471

Cited by 5 publications

(3 citation statements)

References 24 publications

(24 reference statements)

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“…Li et al [19] established a coal pillar mechanical model based on the theory of falling arch, theoretically determined the width of the protective coal pillar between the retracement channel, and verified its mechanical response characteristics using the FLAC 3D calculation model. Qin et al [20] proposed the relationship between the working resistance of hydraulic supports and the immediate roof sinking angle under the spatial relationship between the retracement channel and the roof fracture and determined the reasonable time for the arrangement of the retracement channel. Ma et al [21] analyzed the failure process of tunnels under different conditions and discussed the failure process and final failure mode of tunnels.…”

Section: Introductionmentioning

confidence: 99%

Study on the Stress Evolution and Strengthening Support Timing of the Retracement Channel under the Super-Thick Nappe

Zhu,

Yue,

Gao

et al. 2023

Sustainability

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The superposition effect of the advanced support pressure of the working face in the final mining stage and the lateral support stress of the roadway is a key factor affecting the stability of the retracement channel. To study the stress evolution of the retracement channel under the super-thick nappe and the timing of strengthening support, this paper takes the mining of the 360808 working face in Xinji No. 1 Mine as the engineering background, analyzes the occurrence conditions of the working face and the measured rock pressure law, and constructs a roof structure model of the retreat area. The UDEC discrete element numerical simulation software was used to analyze the evolution characteristics of concentrated stress and the failure law of surrounding rock around the retracement channel under gradual excavation conditions. Based on the relationship between the position of the main roof fracture and the stability of the surrounding rock of the retracement channel, the instability mechanism of the surrounding rock of the retracement channel was revealed. A mechanical model of the surrounding rock of the retracement channel under the condition of a gradient coal pillar was established, and the energy criterion K for the instability of the surrounding rock was obtained. The method of adding anchor cables to strengthen the support of the surrounding rock of the retracement channel was proposed. The results indicate that the accumulation of energy in the surrounding rock of the retracement channel is greater than the internal consumption of energy, which is the direct reason for the instability of the surrounding rock of the retracement channel. The time to strengthen the support of the roof is when the working face is 15 m away from the retracement channel. According to the analysis of on-site monitoring results, the roof convergence and the two-sides convergence before and after strengthening the support were reduced by 90 mm and 140 mm, respectively. Under the strengthening of support, the slope of the retracement channel in the 360808 working face is slight, without roof fall, and the surrounding rock of the channel is effectively controlled, which is of great significance for ensuring the safe application of the retracement channel. It has reference value for the safety production of surrounding mines and is conducive to promoting the sustainable development of local resource-based society and economy.

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Section: Introductionmentioning

confidence: 99%

Study on the Stress Evolution and Strengthening Support Timing of the Retracement Channel under the Super-Thick Nappe

Zhu,

Yue,

Gao

et al. 2023

Sustainability

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show abstract

“…Longwall comprehensive mechanized top coal caving mining (LCMTCCM) is widely used in thick and extra‐thick coal seams in China 4,5 . In the LCMTCCM system, a large cross‐section channel parallel to the working face is used to turn and retrace equipment during the final mining period 6,7 . The large cross‐section channel is called the retracement channel, and the virgin coal between the retracement channel and main roadways is called the end‐mining coal pillar.…”

Section: Introductionmentioning

confidence: 99%

“…4,5 In the LCMTCCM system, a large cross-section channel parallel to the working face is used to turn and retrace equipment during the final mining period. 6,7 The large cross-section channel is called the retracement channel, and the virgin coal between the retracement channel and main roadways is called the end-mining coal pillar. There are two types of retracement channels during the end mining of fully mechanized top coal caving face: pre-excavation retracement channel and using coal cutter to excavate retracement channel.…”

mentioning

confidence: 99%

Field and simulation study of the rational retracement channel position and control strategy in close‐distance coal seams

et al. 2022

Energy Science & Engineering

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Different from single coal seam mining, the stress evolution in the end mining stage of close-distance coal seams is extremely complex. The unreasonable position and support of the lower retracement channel will cause serious deformation and damage to the surrounding rock. Taking the Yanzishan coal mine as the engineering background, the deformation and failure characteristics of the retracement channel under different overlay environments and the key influencing factors of position design were discussed by numerical simulation, theoretical analysis, and field investigation. The results show that the coupling superposition of upper coal pillar high stress and mining dynamic pressure will form a dangerous area with severe ground pressure behavior. The retracement channel should be preferentially designed in zone A (overlying mining roadways), followed by zone B (overlying end-mining coal pillar), and finally, zone C (overlying section coal pillar). In addition, the rational horizontal distance between the lower retracement channel and the upper end-mining coal pillar should make the channel in a good stress environment. The safety distance between the retracement channel and the nearest main roadway (end-mining coal pillar width) should be greater than the severe range of advance abutment pressure. Finally, the design principle and control strategy for the lower retracement channel is proposed. The feasibility and rationality of the study are verified by industrial applications.

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Investigation of the Optimal Layout of the Roadway in Closely Spaced Ultra‐Thick Coal Seams Mining with Remaining Coal Pillars

Gao

Tian

et al. 2021

Shock and Vibration

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The reasonable layout of the roadway in closely spaced, ultra-thick coal seam mining is of great significance to mining safety. Based on the research background of repeated roof leaks in the process of repairing the return air roadway in working face No. 30503 in the Tashan Coal Mine, theoretical analysis, in situ engineering testing, and numerical simulation were jointly adopted to evaluate the stability of the return air roadway under two schemes of repairing the original return air roadway and excavating a new return air roadway. The results show that the vertical mining-induced fissure above the roadway will cause severe damage to the roadway due to the influence of working-face mining when restoration of the roadway excavation is adopted. When choosing to excavate a new return air roadway, the new return air roadway just staggers the vertical cracks located in the top slab of the original return air roadway, putting the roadway in a state of stress reduction, making the roadway itself more stable and conducive to support. Therefore, the new air return tunnel was selected to establish the working face. To ensure safety of the working face during the mining of the original return air roadway, the original return air roadway was filled with high water content materials. Site investigation data show that this material plays a cushioning role in the filling section of the original return air roadway during the mining of the 30503 working face, and the deformation of the new return air roadway during the filling section crossing the original return roadway is stable and well controlled.

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Stability and Control of Retracement Channels in Thin Seam Working Faces with Soft Roof

Cited by 5 publications

References 24 publications

Study on the Stress Evolution and Strengthening Support Timing of the Retracement Channel under the Super-Thick Nappe

Study on the Stress Evolution and Strengthening Support Timing of the Retracement Channel under the Super-Thick Nappe

Field and simulation study of the rational retracement channel position and control strategy in close‐distance coal seams

Investigation of the Optimal Layout of the Roadway in Closely Spaced Ultra‐Thick Coal Seams Mining with Remaining Coal Pillars

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