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

Li, Xiaolong; Liu, Changwu; Liu, Yang; Xie, Hui

doi:10.1155/2017/3629156

Cited by 18 publications

(14 citation statements)

References 15 publications

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“…The technologies of hydraulic fracturing to weaken hard roofs in advance have been gradually accepted in coal mines of China recently [54][55][56]. In mining engineering, there are two requirements for the application of the proposed mining-induced failure criteria: (1) There is a soft layer being sandwiched between the two interactional hard roof structures; (2) the equilibrium condition of structures should satisfy Equations (6), (13), and (14). Further, correlative parameters of IHRS need to be re-determined considering the varying geological conditions.…”

Section: Discussionmentioning

confidence: 99%

“…To effectively control the deformation of tail entry in the strong mining pressure zone, it is important to understand the mechanical behavior of the hard roof structures above the side of Gob 1 during retreat of the mining working face of Panel 2. Mechanical behavior of hard roof structures mainly refers to the separation, fracture, rotation, slipping, and yielding when the stress reaches the strength of structures [9][10][11][12][13][14][15][16][17]. At present, stability analyses of mechanical behavior are mainly concentrated on the single structure in one layer.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…e process of exposing the roof to loads, bending deformation, and breakage is also a process of energy accumulation, conversion, and release. It primarily involves strain, gravitational potential, kinetic, surface, and vibration energies [24][25][26][27]. Object energy changes can be divided into dissipation and accumulation.…”

Section: Hard Roof Energy Evolution and Failure Mechanismsmentioning

confidence: 99%

Study on Rock Burst Event Disaster and Prevention Mechanisms of Hard Roof

Zhou

Liu

Zhang

et al. 2019

Advances in Civil Engineering

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Coal mining under hard roofs is jeopardized by rock burst-induced hazards. In this paper, mechanisms of hard roof rock burst events and key techniques for their prevention are analyzed from the standpoint of energy evolution within geological conditions typical of the hard roofs found in Chinese coal mines. Equations used to calculate the total strain energy densities of the coal-rock mass and hard roof working face are derived. Moreover, several failure-causing energy evolution rules are analyzed under various conditions. Various rock roof and coal mass thicknesses and strengths are considered, and a method of preventing hard roof rock burst events is proposed. The results obtained show that rock burst events can be facilitated by high stress concentrations, significant accumulation of strain energy in the coal-rock mass, and rapid energy release during roof breakage. The above conditions are subdivided into two classes: energy accumulation and energy release. The total strain energies of the coal mass and working faces in the roof are positively correlated with the roof thickness, roof strength, and coal mass strength. The coal mass strength primarily influences the overall accumulation of energy in the working face, and it also has the largest effect on the total energy release (i.e., the earthquake magnitude).

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“…In addition, the support crashing mechanism was studied during the mining of an extra-thick coal seam with hard roofs, indicating that the high hardness of the top coal and the insufficient resistance of the supports were the primary causes of the crashed supports [7]. Li et al [8] adopted the thick-plate theory to study the fracturing characteristics and the span of thick and hard roofs, and microseismic monitoring was used to analyse the energy characteristics of roof fracturing. Zhenlei et al [9] compared the occurrence of rockburst in stopes when the mining methods of top-coal caving and slicing mining were used.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation on fracturing behaviour of hard roofs at different levels during extra-thick coal seam mining

et al. 2020

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In fully mechanized caving mining of extra-thick coal seams, the movement range of overburden is wide, resulting in the breakage of multilayer hard roofs in overlying large spaces. However, the characteristics, morphology and impact effect of hard roofs at different levels are different and unclear. In this study, a secondary development was used in the numerical simulation software ABAQUS, and the caving of rock strata in the finite-element software was realized. The bearing stress distribution, fracturing morphology and impact energy characteristics of hard roofs at different levels were studied to reflect the action and difference of hard roof failure on the working face; thus, revealing the mechanism of the strong ground pressure in stopes, and providing a theoretical basis for the safe and efficient mining of extra-thick coal seams with hard roofs.

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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

Cited by 18 publications

References 15 publications

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

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

Study on Rock Burst Event Disaster and Prevention Mechanisms of Hard Roof

Numerical simulation on fracturing behaviour of hard roofs at different levels during extra-thick coal seam mining

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