Analysis of Hydro-fracturing Technique Using Ultra-deep Boreholes for Coal Mining with Hard Roofs: a Case Study

Zheng, Jianwei; Wen-jun, JU; Sun, Xiaodong; Jiang, Pengfei; Yang, Zheng; Ma, Zhaorui; Zhu, Lihua; Yi, Bingding

doi:10.1007/s42461-020-00334-2

Cited by 8 publications

(4 citation statements)

References 55 publications

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“…Xie SR [ 23 , 24 ] analyzed the stress relief effects of the borehole diameter and angle on high-stress roadways, ultimately determining that large-diameter boreholes are suitable for stress relief purposes. Zheng JW [ 25 ] proposed segmental hydraulic fracturing to weaken roof strata and release pressure. Zhang JP [ 26 ] and Chen B [ 27 ]suggested the use of a shaped steel pipe-concrete support for deep high-stress roadways.…”

Section: Introductionmentioning

confidence: 99%

Controlled reconstruction and application research of lateral overlying strata structure in high-gas mines with thick-hard roofs for a fully-mechanized top-caving face

Chang,

Wang,

Qin

et al. 2024

Heliyon

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Section: Introductionmentioning

confidence: 99%

Controlled reconstruction and application research of lateral overlying strata structure in high-gas mines with thick-hard roofs for a fully-mechanized top-caving face

Chang,

Wang,

Qin

et al. 2024

Heliyon

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“…Bai et al [ 12 ] determined mine damage and induced cracking through drilling tests, and established an empirical relationship between the failure zones in the vertical and horizontal directions. Zheng et al [ 13 ] used the deep borehole stress meters to evaluate the fracturing effect of the hard roof after the ultra-deep borehole hydro-fracturing. Zhu et al [ 14 ] used passive velocity tomography and acoustic emission to study the internal microfractures and energy evolution of coal samples during true-triaxial compression.…”

Section: Introductionmentioning

confidence: 99%

Simulation and On-Site Detection of the Failure Characteristics of Overlying Strata under the Mining Disturbance of Coal Seams with Thin Bedrock and Thick Alluvium

Zhang,

Guo,

et al. 2024

Sensors

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When mining deep coal seams with thin bedrock and thick alluvium, the collapse and fracture of thin bedrock layers may cause geological disasters, such as water inrush and sand inrush of the mining face. Comprehensively obtaining the response data of coal mining and reasonably analyzing the failure characteristics of overlying strata are helpful in guiding safe production. In this study, the caving zone heights of overlying strata are obtained by field detection during layered mining. Then, the caving zone heights during the once-full-height mining are evaluated by theoretical analysis. Further, the force and failure characteristics of coal–rock structures under different mining conditions are compared by the simulation detection and analysis. Finally, the results of on-site observation, theoretical analysis, and simulation detection are compared and discussed, and an optimized mining technology is proposed to ensure safe mining. The research shows the caving zone heights of on-site and simulation detections are, respectively, 14.65 m and 13.5 m during bottom-layer mining, which is larger than the caving zone heights of the top-layer coal mining. During once-full-height mining, the maximum caving zone height of simulation detection is 21 m, which is in between two standard results. For the mechanical responses of an aquiclude clay layer under thick loose alluvium, the maximum disturbance displacement of clay aquiclude is 5.8 m during layered mining, which is slightly larger than the disturbance displacement of once full-height mining; however, the maximum stress of the clay layer is 25 MPa during once-full-height mining, which is larger than the maximum stress of clay layer during layered mining. For the clay aquiclude failure, the clay layer during layered mining is in the deflection deformation area, and there is no obvious fracture structure to inrush the water and sand of thick loose alluvium; however, the clay layer during once-full-height mining is prone to produce obvious fracture structure. Therefore, the layered mining technology can effectively reduce and prevent the water/sand inrush disaster of mining working face.

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“…Roof accidents have a high incidence and fatality rate, and are the first of the five major disasters in coal mines, especially in the mining of coal seams under thick hard strata [1,2]. However, more than 50% of coal mines are currently operating under thick hard rocks with high strength, undeveloped joints and fissures, good integrity and strong energy storage capacity in China [3][4][5]. Compared with general roofs, the pressure step of a hard roof working face is large and the accumulated elastic energy is released instantaneously, which leads to strong pressure behavior, especially under the condition of large mining height and fully mechanized top-coal mining.…”

Section: Introductionmentioning

confidence: 99%

Mining-Induced Stress Control by Advanced Hydraulic Fracking under a Thick Hard Roof for Top Coal Caving Method: A Case Study in the Shendong Mining Area, China

2021

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Fully mechanized top-coal caving mining with high mining height, hard roofs and strong mining pressure are popular in the Shendong mining area, China. The occurrence of dynamic disasters, such as rock burst, coal and gas outburst, mine earthquakes and goaf hurricanes during the coal exploitation process under hard roof conditions, pose a threat to the safe production of mines. In this study, the characteristics of overburden fracture in fully mechanized top-coal caving with a hard roof and high mining height are studied, and the technology of advanced weakening by hard roof staged fracturing was proposed. The results show that the hard roof strata collapse in the form of large “cantilever beams”, and it is easy to release huge impact kinetic energy, forming impact disasters. After the implementation of advanced hydraulic fracturing, the periodic weighting length decreases by 32.16%, and the length of overhang is reasonably and effectively controlled. Ellipsoidal fracture networks in the mining direction of the vertical working face, horizontal fracture networks perpendicular to the direction of the working face, and near-linear fracture planes dominated by vertical fractures were observed, with the accumulated energy greatly reduced. The effectiveness of innovation technology is validated, and stress transfer, dissipation and dynamic roof disasters were effectively controlled.

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Analysis of Hydro-fracturing Technique Using Ultra-deep Boreholes for Coal Mining with Hard Roofs: a Case Study

Cited by 8 publications

References 55 publications

Controlled reconstruction and application research of lateral overlying strata structure in high-gas mines with thick-hard roofs for a fully-mechanized top-caving face

Controlled reconstruction and application research of lateral overlying strata structure in high-gas mines with thick-hard roofs for a fully-mechanized top-caving face

Simulation and On-Site Detection of the Failure Characteristics of Overlying Strata under the Mining Disturbance of Coal Seams with Thin Bedrock and Thick Alluvium

Mining-Induced Stress Control by Advanced Hydraulic Fracking under a Thick Hard Roof for Top Coal Caving Method: A Case Study in the Shendong Mining Area, China

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