Fracture failure analysis of hard–thick sandstone roof and its controlling effect on gas emission in underground ultra-thick coal extraction

Wei, Wang; Wang, Chenghao; Wang, Haifeng; Liu, Hong Yong; Wang, Liang; Li, Wenyuan; Jiang, Jingyu

doi:10.1016/j.engfailanal.2015.04.016

Cited by 96 publications

(48 citation statements)

References 20 publications

(28 reference statements)

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“…(1) When the roof-controlled backfill ratios are 40% and 60%, the peak value and range of influence of the advanced abutment stress on the working panel are the same with those found when using a caving mining method. (2) In the case of a varying roof-controlled backfill ratio (82.5%, 91%, 93% and 97%), the advanced abutment stresses on working panels decrease, along with their range of influence. When the ratio reaches 97%, the peak stress decreases from 44.9 MPa while using a mining caving method, to 24.4 MPa: the range of influence of the stresses decreases from 45 m to 25 m, which also significantly reduces the extent of stress concentration in front of the working panel.…”

Section: Stope Stress Distributionsmentioning

confidence: 97%

“…This coal mine was built in December, 1993 with an estimated service life of 90 years. The designed production capacity is 5 million tons per year, and its total area is 105.05 km 2 .…”

Section: Study Sitementioning

confidence: 99%

“…The term hard roofs [1,2] refers to the strata occurring above coal seams or above thin immediate roofs; they have large thicknesses, poor joint development, and high rock strength and bearing capacity. Owing to the significantly variability of hard roof conditions in China, their thickness can vary from tens to hundreds of metres, and the coal resource reserves under hard roofs account for about 30% of overall reserves.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Modelling of Mechanical Behavior of Coal Mining Hard Roofs in Different Backfill Ratios: A Case Study

Li¹,

Zhou²,

Zhang³

et al. 2017

Energies

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Abstract:In coal mining hard roofs are one of the main factors causing the occurrence of rock bursts in working panels. To solve this problem, the solid backfill coal mining (SBCM) technique is proposed and used as an effective measure to prevent the rock bursts induced by hard roofs. However, due to the different backfill ratios of working planes, the control effects on hard roofs are quite unique. By using a numerical simulation, this study simulates the deformation of hard roofs and distributions of stress and strain energies in different roof-control backfill ratios, so as to reveal the control mechanisms of SBCM on hard roofs. The results show that, when the roof-controlled backfill ratio are 0, 40% and 60%, the ratio exerts no influence on the distributions of advanced abutment stress and strain energies. While for roof-control backfill ratios of 82.5%, 91% and 93%, the advanced abutment stress and strain energies decrease significantly, but the increment of the ratio exerts little influence on the decrease. When the roof-control backfill ratio reaches 97%, the advanced abutment stress and strain energies again decrease. In this context, the stress concentration factor is only 1.5 and the peak strain energy is 544 kJ/m 3 , the stress concentration factor and peak strain energy decrease by 45.7% and 63.9%, respectively, compared with the caving method. As the roof-controlled backfill ratio rises, backfill materials tend to support hard roofs, thus significantly preventing dynamic hazards.

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Section: Stope Stress Distributionsmentioning

confidence: 97%

“…This coal mine was built in December, 1993 with an estimated service life of 90 years. The designed production capacity is 5 million tons per year, and its total area is 105.05 km 2 .…”

Section: Study Sitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Modelling of Mechanical Behavior of Coal Mining Hard Roofs in Different Backfill Ratios: A Case Study

Li¹,

Zhou²,

Zhang³

et al. 2017

Energies

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show abstract

“…He et al [41] analyzed the rockburst prevention by cutting the hard roof directionally in advance under mechanical behaviors of the deep-hole directional fracturing of hard roof. To reduce the effect of the fracture failure of the overlying hard-thick sand-stone main roof on the gas permeability in the mining coal seams, Wang et al [42] recommended shortening the hanging length of the main roof failure span using hydraulic presplitting. Zhang, et al [43] determined the breaking form, order, step of the over roofs based on the hinge balanced cantilever beam structure model with the directional blast technology.…”

Section: Introductionmentioning

confidence: 99%

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

et al. 2019

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Due to the additional abutment stress, interactional hard roof structures (IHRS) affect the normal operation of the coal production system in underground mining. The movement of IHRS may result in security problems, such as the failure of supporting body, large deformation, and even roof caving for nearby openings. According to the physical configuration and loading conditions of IHRS in a simple two-dimensional physical model under the plane stress condition, mining-induced failure criteria were proposed and validated by the mechanical behavior of IHRS in a mechanical analysis model. The results indicate that IHRS, consisting of three interactional parts-the lower key structure, the middle soft interlayer, and the upper key structure-are governed by the additional abutment stress induced by the longwall mining working face. The fracture of the upper key structure in IHRS can be explained as follows: Due to the crushing failure, lower key structure, and middle soft interlayer yield, the action force between the upper and lower key structures vanishes, resulting in fracture of the upper key structure in IHRS. In a field case, when additional abutment stress reaches 7.37 MPa, the energy of 2.35 × 10 5 J is generated by the fracture of the upper key structure in IHRS. Under the same geological and engineering conditions, the energy generated by IHRS is much larger than that generated by a single hard roof. The mining-induced failure criteria are successfully applied in a field case. The in-situ mechanical behavior of the openings nearby IHRS under the mining abutment stress can be clearly explained by the proposed criteria.

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“…Thus, this kind of roof will gather a lot of strain energy in the coal seam and surrounding rock. When the thick and hard roof breaks, it can release huge energy and produce strong dynamic load effect, which can easily lead to support destruction, working face collapse, rock burst, and other events [2,3]; the problem exists in many mining areas in China such as Datong, Zaozhuang, Tonghua, Hegang, and Qitaihe; Russia and Western Europe countries also have similar problems. So it is the key to ensure the safe production of mine by accurately grasping the breaking span of thick and hard roof and the distribution of strain energy in coal seam.…”

Section: Introductionmentioning

confidence: 99%

The Breaking Span of Thick and Hard Roof Based on the Thick Plate Theory and Strain Energy Distribution Characteristics of Coal Seam and Its Application

Liu

et al. 2017

Mathematical Problems in Engineering

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In mining engineering, the thick and hard roof threatens the safe production. Based on Reissner plate theory and combined with weighted residual method, with four edges clamped as the boundary conditions, this paper deduces the theoretical formula of the first breaking span of thick and hard roof. Based on Vlasov plate theory, with four edges simply supported as the boundary conditions, this paper deduces the theoretical formula of the periodic breaking span of thick and hard roof. The two formulas are used to verify the breaking span of thick and hard roof of Tashan Coal Mine, proving that its accuracy is higher than that of traditional beam theory. This paper studies the distribution characteristics of strain energy density in front of the coal seam during the mining process by numerical simulation, which is compared with the results of field microseismic experiments. It is found that the strain energy density of the coal seam has a good correlation with the probability of microseismic events. This paper provides theoretical support for more precise calculation of breaking span of the thick and hard roof and technical support for the practical stability analysis of the surrounding rock under the thick and hard roof.

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Fracture failure analysis of hard–thick sandstone roof and its controlling effect on gas emission in underground ultra-thick coal extraction

Cited by 96 publications

References 20 publications

Numerical Modelling of Mechanical Behavior of Coal Mining Hard Roofs in Different Backfill Ratios: A Case Study

Numerical Modelling of Mechanical Behavior of Coal Mining Hard Roofs in Different Backfill Ratios: A Case Study

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

The Breaking Span of Thick and Hard Roof Based on the Thick Plate Theory and Strain Energy Distribution Characteristics of Coal Seam and Its Application

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