Analysis of fracture mechanism for surrounding rock hole based on water-filled blasting

Wang, Jun; Yang, Jianghao; Wu, Fengfeng; Xu, Fangfang; Faisal, Shams Al

doi:10.1007/s40789-020-00327-y

Cited by 47 publications

(27 citation statements)

References 16 publications

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“…Before running the LS-DYNA 3D program, five elements are designated as observation points to facilitate analyzing and processing the numerical results [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. As shown in Figure 3, points H69786, H68778, H68787, H62503, and H61486 are selected at the lower part of the centerline of two blast holes, which are signed as A, B, C, D, and E, respectively.…”

Section: Simulation Results and Analysismentioning

confidence: 99%

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Wang

et al. 2021

Shock and Vibration

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In the traditional presplitting blasting, the presplit holes are generally uniformly initiated, which causes local damage to the retained rock mass while forming the damping ditch. In order to determine the optimal delay time of the precise delay initiation hole by hole, the finite element software ANSYS/LS-DYNA is used to build a blasting model of the concrete, which includes concrete, explosive, and air to simulate the crack forming process of the presplitting hole under various initiation modes. Four kinds of initiation modes for blasting, namely, simultaneous initiation with 0 ms, 9 ms, 12 ms, and 15 ms of delay between adjacent holes, are set up to determine the exact delay time of the best presplitting effect. The simulation results show that when the prehole detonates simultaneously, the inner hole crack penetrates the fastest, but the peak stress around the hole is up to 147.9 MPa. When interhole delayed initiation is used, although the time of interhole crack penetration is prolonged, the stress coupling is generated around the precrack and the maximum stress is obviously reduced. The maximum stress generated under the three delayed initiation conditions is only 76.8 MPa. Considering the requirement of damage control of surrounding rock mass and the rapid formation of precrack, 9 ms delay time is determined as the precise delay time of this test.

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Section: Simulation Results and Analysismentioning

confidence: 99%

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Wang

et al. 2021

Shock and Vibration

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“…Fracturing pumps, fracturing pipes, grooving drill bits, and other equipment are used to fracture roofs in the process of hydraulic fracturing to reduce the integrity of the roofs and achieve the goal of ground pressure control (Lu et al 2015;Yu and Duan 2014). By using liquid explosive, confined waterfilled blasting technology can not only realize safe blasting but also improve the blasting ability to the maximum extent to reduce the breaking strength of hard roofs Wang et al 2020). However, constrained by the equipment, drilling hole length, and other conditions, the above technologies are limited to underground operation only, and the control range is within 50 m, which cannot fracture hard roofs at high level.…”

Section: Introductionmentioning

confidence: 99%

Controlling mine pressure by subjecting high-level hard rock strata to ground fracturing

Gao

Kuang²,

Zhang³

et al. 2021

Int J Coal Sci Technol

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When mining extra-thick coal seams, the main cause of strong ground pressure are the high-level thick and hard strata, but as yet there is no active and effective control technology. This paper proposes the method of subjecting hard roofs to ground fracturing, and physical simulation is used to study the control effect of ground fracturing on the strata structure and energy release. The results show that ground fracturing changes the structural characteristics of the strata and reduces the energy release intensity and the spatial extent of overburden movement, thereby exerting significant control on the ground pressure. The Datong mining area in China is selected as the engineering background. An engineering test was conducted on site by ground horizontal well fracturing, and a 20-m-thick hard rock layer located 110 m vertically above the coal seam was targeted as the fracturing layer. On-site microseismic monitoring shows that the crack propagation length is up to 216 m and the height is up to 50 m. On-site mine pressure monitoring shows that (1) the roadway deformation is reduced to 100 mm, (2) the periodic weighting characteristics of the hydraulic supports are not obvious, and (3) the ground pressure in the working face is controlled significantly, thereby showing that the ground fracturing is successful. Ground fracturing changed the breaking characteristics of the high-level hard strata, thereby helping to ameliorate the stress concentration in the stope and providing an effective control approach for hard rock.

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“…Wang et al [8] detailed the state of the art in research on top coal drawing mechanisms in Long wall top coal caving (LTCC) by examining the relevant literature over the past two decades. Wang et al [9] revealed that the fracturing of the surrounding rock during underwater blasting is due to the combined action of shock and stress waves for the initial rock breakage and subsequent water expansion. Song et al [10] analyzed the modulus degradation of concrete subjected to multilevel compressive cyclic loading.…”

Section: Introductionmentioning

confidence: 99%

Application of Presplitting Blasting Technology in Surrounding Rock Control of Gob‐Side Entry Retaining with Hard Roof: A Case Study

Gong

Tan

Liu

et al. 2021

Advances in Materials Science and Engineering

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Through the analysis of the mining situation and geological data of Qidong mine and working face, the key factors affecting the roof cutting and pressure relief roadway retention along the goaf are defined. Combined with numerical simulation and field test, the reasonable parameters of combined presplitting blasting of deep hole and shallow hole in hard roof are determined, and the roof cutting effect is tested through field observation and borehole peeping. The comprehensive control measures for the surrounding rock of 7135 roadway with roof cutting and pressure relief and gob retaining are formulated, including safety assurance technical measures, such as advanced precrack and seam cutting, roof reinforcement and support, gangue retaining protection beside the roadway, lagging temporary support, and on-site industrial test monitoring scheme. Aiming at the hard rock roof, the “deep hole + shallow hole” presplitting blasting roof cutting technology is developed, and the economic and reasonable blasting parameters are determined. The drilling peep results show that the implementation effect of presplitting blasting technology is good. The results showed that deep holes and shallow holes with small spacing and parallel to each other shall be arranged on the planned seam line. The peeping results show that the crack formation rate in the charging section exceeds 85% in the process of deep hole blasting. In shallow hole blasting, the crack formation rate of charging section is more than 90%.

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Analysis of fracture mechanism for surrounding rock hole based on water-filled blasting

Cited by 47 publications

References 16 publications

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Controlling mine pressure by subjecting high-level hard rock strata to ground fracturing

Application of Presplitting Blasting Technology in Surrounding Rock Control of Gob‐Side Entry Retaining with Hard Roof: A Case Study

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