Width design for gobs and isolated coal pillars based on overall burst-instability prevention in coal mines

Zhang, Junfei; Jiang, Fuxing; Zhu, Sitao; Zhang, Lei

doi:10.1016/j.jrmge.2015.12.006

Cited by 48 publications

(21 citation statements)

References 6 publications

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“…According to Section 4.1, the fracture line of the main roof in 11215 working face was located 30 m inside the chain pillar. erefore, we can control the fracture line on the chain pillar side by adjusting the width of the chain pillar [30][31][32].…”

Section: Advances In Civil Engineeringmentioning

confidence: 99%

Mechanism of Dynamic Failure in Roadways with Thick and Competent Roof Strata: A Case Study

Guo

Feng

et al. 2019

Advances in Civil Engineering

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Rock and coal dynamic failures have a higher chance to occur when thick and competent roof strata are presented, which can build up a high level of energy. This paper studied the fracturing characteristics of the competent roof strata during longwall face retreat and their effects on roadways’ stability to gain an improved understanding of the rock dynamic failure occurred in roadways as well as the associated ground controls. The results indicated that the main reason of dynamic failure in roadways was the structural change of lateral main roof over a chain pillar, which transformed from the cantilever beam in the period of primary mining impact (PMI) to the triangular arch in the period of secondary mining impact (SMI). Based on corresponding mechanical models developed for the lateral main roof over the chain pillar, it was calculated that the force on roadways’ roof in the period of SMI was 3.7 times larger than that in the period of PMI. Then, the dynamic failure control method of increasing the chain pillar width was proposed. The stress distribution and deformation of roadways with different chain pillar widths were simulated using FLAC3D. The results indicate that as the pillar width increases, the influence of secondary mining on roadways’ stability decreases, and a threshold of not less than 30 m pillar width was suggested. The outcomes of this study would provide guidance for the design of chain pillars where thick and competent roof strata are presented.

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Section: Advances In Civil Engineeringmentioning

confidence: 99%

Mechanism of Dynamic Failure in Roadways with Thick and Competent Roof Strata: A Case Study

Guo

Feng

et al. 2019

Advances in Civil Engineering

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“…Aguado and González (2009) conducted studies in tow mines and observed that sublevel caving is one of the methods primarily influencing the stress state, thus the condition of sublevel caving is an extremely important parameter to prevent disaster in mines. Zhang et al (2016) considered that if the width of the isolated coal pillar is not sufficiently large, the shallow coal seam would be damaged at first, and, subsequently, the high abutment pressure would be transferred to the deep coal seam that might cause an overall burst-instability accident. Pan et al (2009) considered that the crack is primarily a tear-type crack under quasi-static loading, and could be analyzed with the mode I crack theory using the three-point bending experiment.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and charge signal characteristics in coal material failure under different loading paths

Ding

Xiao

et al. 2019

Int J Coal Sci Technol

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Rock burst is a catastrophic dynamic disaster caused by sudden failure and instability of coal, loading paths play an important role in the failure of coal, the coal failure process is associated with charge exception information. Hence, violent coal failure mechanics and time-frequency domain distribution of charge signal such as rock burst under different loading paths should be studied in-depth. In this paper, grade and cyclic loading test were carried out for coal with impact tendency samples produced by blocks cored from 800 depth in Xiaoqing coal mine of the Tiefa coal group in northeast China. Theory discussion was carried out for the result of stress and strain, frequency-spectra analysis was conducted for the wavelet charge data, figures showing the evolution mechanism of mechanical properties and the relationship of timefrequency domain amplitude of charge signals in coal with different loading paths and stage were obtained. The failure process and characteristics of coal under different loading paths were summarized. It found that the loading path changed the manner of energy accelerate-release, there were more plastic strain generation in coal under cyclic loading than that under grade loading, the former was more likely to cause greater damage and failure, then the strength of coal under cyclic loading is generally lower than that under grade loading, an energy conversion mechanical model of stress, damage and deformation was developed and explained the effect of the loading path. Charge signal was primarily distributed in the strengthening and peak stages, where there was a high amplitude pulse at each stress drop. The charge pulse was a type of low frequency signal with a primary frequency distribution range of 1-100 Hz. Discussion on the charge generating mechanism from the perspective of friction slip, it demonstrated that the charge obtained during the coal failure process directly to stress loaded on and damage, the result verified it better. We propose that the research results in this study could be efficiently applied to daily mining activities, to provide an early warning and effectively avoid rock burst disaster.

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“…In addition, due to the influences of mining disturbance caused by the lower seam extraction, and mining activities in overlying strata and lateral roof strata tend, the stopping roadways and coal pillars would seriously deform, resulting in a series of adverse consequences. This can lead to strong ground pressure behavior of working faces, rib‐spalling of coal walls, and even rockbursts …”

Section: Introductionmentioning

confidence: 99%

Experimental study on the overburden movement and stress evolution in multi‐seam mining with residual pillars

Tian

Yang

Sun

et al. 2019

Energy Science & Engineering

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When faced with multi‐seam mining, some coal pillars are left to support the overlying strata when mining the lower seam, where stress concentration usually occurs. When the working face in the lower seam advances to the area influenced by these coal pillars, high ground pressure behavior occurs. Furthermore, the instability of coal pillars under the participation of the roof may induce rock burst, which threaten the safe production of coal mine. To study the roof strata movement and coal pillar instability in multi‐seam mining, a coal mine in Datong was taken as an example. Firstly, the bursting liability of coal and rock stratum was tested. The test results show that the 7#, 8#, and 11# coal seams in the mining area all have strong bursting liability. And the roof was dominated by siltstone and firestone, which also have strong bursting liability. Then, based on the geological conditions of the coal mine, we investigated roof movement and instability of the coal pillar during multi‐seam mining through physical simulation. The simulation results indicate that multi‐seam mining aggravates the roof damage, which leads to the increase in the fracture range of overlying strata, and that the failure height increases from 46 to 121 m. In addition, the detailed distribution of stress on residual coal pillars and its influence on the lower working face were studied through numerical simulation. The results show that, when the working face 8707 of the 8# coal seam advances to a horizontal distance of 20 m from the coal pillar, it enters the influence zone. As the working face advances beneath the coal pillar, the stress reached to 24 MPa. Moreover, when the working face passes by the coal pillar, the coal pillar is cutoff, thus affecting the working face.

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Width design for gobs and isolated coal pillars based on overall burst-instability prevention in coal mines

Cited by 48 publications

References 6 publications

Mechanism of Dynamic Failure in Roadways with Thick and Competent Roof Strata: A Case Study

Mechanism of Dynamic Failure in Roadways with Thick and Competent Roof Strata: A Case Study

Mechanical properties and charge signal characteristics in coal material failure under different loading paths

Experimental study on the overburden movement and stress evolution in multi‐seam mining with residual pillars

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