In situ explorations on zonal disintegration of roof strata in deep coalmines

Tan, Yunliang; Ning, Jianguo; Li, H.T.

doi:10.1016/j.ijrmms.2011.11.015

Cited by 55 publications

(10 citation statements)

References 7 publications

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“…Hence, the borehole television approach has been widely applied to identify lithology, determine coal seam thickness, and to observe the separation of roadway roofs and deformation of surrounding rocks [12][13][14][15][16]. Tan et al used a borehole camera technology to explore the zonal disintegration developing process in roof strata influenced by multiple mining activities [17][18][19]. Xiong et al used the three-borehole method (multi-point displacement measuring, the double end seal with water injection method and borehole television photographing) for the overburden failure law in an upper protected coal seam while the lower protective seam is mined [20].…”

Section: Introductionmentioning

confidence: 99%

Visual Exploration of the Spatiotemporal Evolution Law of Overburden Failure and Mining-Induced Fractures: A Case Study of the Wangjialing Coal Mine in China

et al. 2017

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Abstract:The borehole television approach is an effective way of detecting mining-induced fractures in overburden strata as it can visualize fractures to facilitate a quantitative analysis of size, quantity, length, and other features. In this article, the borehole television approach is applied on panel 20105 of the Wangjialing Coal Mine in China to investigate the overburden movement and spatiotemporal evolution law of mining-induced fractures from the coal seam to ground surface. The results revealed that the overburden strata experienced the phases of roof caving, generation of fracture, bed separation, dislocations, fracture propagation, surface subsidence, and closing of fractures. The process can be divided into the initiation stage, the active stage, and the degradation stage along the mining direction. For exploited working faces, the caved zone height is 2.9-4.11 times the mining height, and the height of the fractured zone is 19. 35-22.19 times the mining height. The height range of the three parts in the fractured zone is 24-26, 40-45, and 30-35 m. Significant fractures were observed in the bending zone.Step subsidence and cracks, which indicate severe damages, were observed on the ground surface above the goaf.

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Section: Introductionmentioning

confidence: 99%

Visual Exploration of the Spatiotemporal Evolution Law of Overburden Failure and Mining-Induced Fractures: A Case Study of the Wangjialing Coal Mine in China

et al. 2017

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“…Subsequently, zonal disintegration was monitored in several mines of the Norilsk minefield by using underground electric soundings and borehole periscope [2]. Furthermore, zonal disintegration was also observed in several deep coal mines of China [5,6], which indicated that zonal disintegration was mainly caused by surrounding rock separating along with the weak structure. Similar phenomenon was captured at the Jinping underground laboratory [7].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three‐Dimensional Bonded Block Model

Tang

Xie

et al. 2019

Advances in Civil Engineering

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Zonal disintegration, a phenomenon of fractured zones and intact zones distributed alternately in deep rock mass, is different from the excavation-damaged zone of shallow rock mass. In this study, bonded block model of 3DEC was employed to study the fracture mode and origination condition of zonal disintegration. Initiation, propagation, and coalescence progress of fracture around the roadway boundary under different triaxial stress conditions are elaborated. Numerical simulation demonstrated that zonal disintegration may occur when the direction of maximum principal stress is parallel to the roadway axis. It is interesting to find that the fracture around the roadway boundary traced the line of a spiral line, while slip-line fractures distributed apart from the roadway boundary. The extent of the alternate fracture zone decreased as the confining pressure increased, and alternate fracture zone was no longer in existence when the confining pressure reaches a certain value. Effects of roadway shape on zonal disintegration were also studied, and the results indicated that the curvature of the fracture track line tends to be equal to the roadway boundary in shallow surrounding rock of the roadway, while the fractures in deep surrounding rock seems unaffected by the roadway shape. Those findings are of great significance to support design of deep underground openings.

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“…Significant experimental efforts have been made to investigate and interpret the evolution of coal permeability. Many factors affect coal permeability, including gas types [3,4], pore pressure, sorption-induced matrix swelling/shrinkage [5][6][7][8][9][10], effective pressure [11,12], water content [13,14] and gas exposure time [15]. Most of the above studies were performed under stress-controlled (unconstrained) boundary conditions to replicate in situ conditions.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Coal Permeability during Gas Injection—From Initial to Ultimate Equilibrium

et al. 2018

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The evolution of coal permeability is vitally important for the effective extraction of coal seam gas. A broad variety of permeability models have been developed under the assumption of local equilibrium, i.e., that the fracture pressure is in equilibrium with the matrix pressure. These models have so far failed to explain observations of coal permeability evolution that are available. This study explores the evolution of coal permeability as a non-equilibrium process. A displacement-based model is developed to define the evolution of permeability as a function of fracture aperture. Permeability evolution is tracked for the full spectrum of response from an initial apparent-equilibrium to an ultimate and final equilibrium. This approach is applied to explain why coal permeability changes even under a constant global effective stress, as reported in the literature. Model results clearly demonstrate that coal permeability changes even if conditions of constant effective stress are maintained for the fracture system during the non-equilibrium period, and that the duration of the transient period, from initial apparent-equilibrium to final equilibrium is primarily determined by both the fracture pressure and gas transport in the coal matrix. Based on these findings, it is concluded that the current assumption of local equilibrium in measurements of coal permeability may not be valid.

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In situ explorations on zonal disintegration of roof strata in deep coalmines

Cited by 55 publications

References 7 publications

Visual Exploration of the Spatiotemporal Evolution Law of Overburden Failure and Mining-Induced Fractures: A Case Study of the Wangjialing Coal Mine in China

Visual Exploration of the Spatiotemporal Evolution Law of Overburden Failure and Mining-Induced Fractures: A Case Study of the Wangjialing Coal Mine in China

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three‐Dimensional Bonded Block Model

Evolution of Coal Permeability during Gas Injection—From Initial to Ultimate Equilibrium

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