Study on the fracture characteristics of thick-hard limestone roof and its controlling technique

Jia, Jia; Cao, Liwen; Zhang, Dianji; Chai, Xiuwei; Liu, Shiqi; Ma, Li; Liu, Ran

doi:10.1007/s12665-017-6914-0

Cited by 33 publications

(9 citation statements)

References 17 publications

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“…In the mechanical analysis, the criteria are obtained in Equations (13) and (14) to protect the upper structure II and upper structure III from slippage failure and crushing failure. Similarly, the criteria are obtained in Equations (15) and (16) to protect the upper key structure from tensile failure and shear failure.…”

Section: Process Of the Fracture For The Upper Key Structurementioning

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: Process Of the Fracture For The Upper Key Structurementioning

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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“…Many researchers have predicted the height of the water-conducting fissures zone. [31][32][33][34][35][36] Chi et al 37 analyzed the water pressure by considering the mining height and aquifer position, and take the ration of water pressure change and mining height as the failure criterion to describe the development of fracture. Bai and Tu 38 point out the mining-induced fracture as main fluid channels and summarized the current study of mining-induced fracture near face regions.…”

Section: Introductionmentioning

confidence: 99%

Failure mechanism and fracture aperture characteristics of hard thick main roof based on voussoir beam structure in longwall coal mining

Zhang

Jin

Song

et al. 2019

Energy Science & Engineering

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The mechanism and fracture aperture of thick hard roof failure were theoretically analyzed from the perspective of elastoplastic mechanics. A uniform load cantilever beam was established by considering the voussoir beam structure and stress condition. According to the stress inverse principle in solving the plane strain problem, the internal stress component analytic solution was deduced. Considering the lateral thrust and shear force and by applying the Mohr-Coulomb failure criterion, the plastic zone boundary equation was obtained. Further analysis of the equivalent stress, equivalent strain, elastic energy density, distortion energy density, and strain energy density was studied with blocks of four different lengths, combined with the rotation angles after failure, to analyze the fissure aperture between straight and curved fracture traces. The theoretical analysis reveals that the deviatoric effect plays the lead role in rupture initiation and propagation; the cracks will deflect during failure, and the fracture trace presents a curved shape. The variation of fracture aperture exhibits a tendency to increase first, then decrease, and then increase along the fracture trace.The analytical approach presented in this paper provides a theoretical basis for determining the main seepage channel flow in underground mining. K E Y W O R D Sfailure mechanism, fracture aperture, theoretical analysis, thick hard roof, underground mining, voussoir beam structure

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“…The permeability of a coal seam, a key parameter reflecting the ability of fluids to flow inside the coal seam and a critical parameter estimating the CO 2 injectivity, determines the success of CO 2 storage in coal seam . The deep coal seam and coal bed methane (CBM) exploration and development are difficult, but the deep coal seam is one of the geological media to potentially store huge amounts of CO 2 . However, deep coal seams with a low in situ permeability and CO 2 injection to the deep coal seam will be in the supercritical state, that is, ScCO 2 , which affect the permeability of coal seam induced by ScCO 2 adsorption‐swelling.…”

Section: Introductionmentioning

confidence: 99%

An experimental study on the permeability changes of anthracite reservoirs in different depths of Qinshui Basin induced by supercritical CO₂ injection

Jia

Cao

2019

Energy Science & Engineering

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Geological sequestration of supercritical CO2 (ScCO2) in deep coal seam has been considered as one of the most promising options for reducing greenhouse gas emission. The permeability of a coal seam, a key parameter estimating the CO2 injectivity, determines the success of ScCO2 storage in the deep coal seam. The deep coal seam has a low initial permeability and a further permeability loss induced by the adsorption‐swelling effects of coal during ScCO2 injection. This paper presents a set of measurements on the permeability changes of anthracite reservoirs in different depths of Qinshui Basin induced by ScCO2 injection. The results indicate that the change in anthracite permeability presents a negative exponential decrease with the buried depth increase. The depth of anthracite reservoir increases from 800 to 1400 m, and its permeability will decrease from 4.59 × 10−2 to 8.04 × 10−4 mD. The permeability change induced by ScCO2 injection is the combining effects of temperature, pressure, and adsorption‐swelling, and the permeability change can be described by a negative exponential model during ScCO2 injection to anthracite reservoir in different depths. The loss coefficient of permeability is up to three magnitudes induced by ScCO2 injection to the anthracite reservoir in the depth of 800 m, 2‐3 magnitudes in 1000‐1200 m, and 1‐2 magnitudes in 1400 m. Although the initial permeability of anthracite reservoirs in the same depth exists differences, the permeability loss coefficient almost has the same magnitudes induced by ScCO2 injection. Comparing with the permeability loss coefficient of the anthracite reservoir in different depths, the permeability variation of the shallow coal seam is more sensitive than the deep induced by ScCO2 injection. However, the deep coal seam has a relatively large fracture pressure, so the allowable ScCO2 injection pressure in the deep coal seam is greater than the shallow.

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Study on the fracture characteristics of thick-hard limestone roof and its controlling technique

Cited by 33 publications

References 17 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

Failure mechanism and fracture aperture characteristics of hard thick main roof based on voussoir beam structure in longwall coal mining

An experimental study on the permeability changes of anthracite reservoirs in different depths of Qinshui Basin induced by supercritical CO₂ injection

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Study on the fracture characteristics of thick-hard limestone roof and its controlling technique

Cited by 33 publications

References 17 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

Failure mechanism and fracture aperture characteristics of hard thick main roof based on voussoir beam structure in longwall coal mining

An experimental study on the permeability changes of anthracite reservoirs in different depths of Qinshui Basin induced by supercritical CO2 injection

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An experimental study on the permeability changes of anthracite reservoirs in different depths of Qinshui Basin induced by supercritical CO₂ injection