Experimental study of coal fracture dynamics under the influence of cyclic freezing–thawing using shear elastic waves

Nikolenko, P. V.; Эпштейн, С. А.; Шкуратник, В. Л.; Ануфренкова, П. С.

doi:10.1007/s40789-020-00352-x

Cited by 46 publications

(21 citation statements)

References 39 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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“…Energy dissipation density is the ratio of the energy used for specimen destruction in the system to the volume of the specimen when the material fails, and it represents the difficulty of material destruction under this load [38][39][40][41][42][43][44]. As it can be seen in Figure 10, when the strain rate increased, the E D of the two kinds of backfill bodies also tended to increase as a whole.…”

Section: Failure Energy Analysesmentioning

confidence: 99%

“…Split Hopkinson pressure bar (SHPB) impact test technology is generally used to study the dynamic characteristics of cemented backfill. Up to now, a large number of studies on the dynamic strength and failure energy of cemented backfill and similar-concrete materials have been carried out [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In Figure 1, the relevant dynamic compression experimental results are sorted out, and it can be seen that with the increase of strain rate, the dynamic strength of cemented backfill also increased.…”

Section: Introductionmentioning

confidence: 99%

Strain Rate Effect on Mechanical Properties of Cemented Backfill under Dynamic and Static Combined Loading

Tao

Wang

et al. 2021

Shock and Vibration

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In order to study the influence of pillar stopping blasting on the stability of cemented backfill, the dynamic impact test under low strain rate (61.1∼86.8 s−1) was conducted on cemented backfill with two kinds of strength using three-dimensional coupled static-dynamic SHPB equipment. At the same time, the strain rate effect of failure mode, dynamic strength factor, and energy transfer of backfill were analyzed. The results show that when the cemented backfill was loaded under different strain rates in the initial three-dimensional static pressure environment, the pore compaction process was no longer obvious but directly entered the elastic deformation stage. Within the range of strain rates, the extreme value of dynamic intensity factor (DIF) of CTB230 was 6.8, while the extreme value of dynamic intensity factor of CTB310 specimen did not appear within the range of strain rates due to the improvement of the internal cementation force between particles. The fracture surfaces of specimens were perpendicular to the direction of load, and the failure mode was mainly the axial tensile failure, and the fracture surfaces were mostly close to the loading end. According to energy calculation, reflected energy accounts for 80.4%∼86.6% of incident energy; dissipated energy, 5.5%∼14.3%; transmitted energy, 5.3%∼7.9%.

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“…At present, the combination of passive support and active support is mainly used, such as steel, bolts, cables, and grouting scheme [12,17]. However, due to the significant difference in the rock mass, both the stability of rock mass and the control of surrounding rock should be adopted to local conditions [18,19]. Coal mine's sedimentary environment and structural environment are complex in the Yunnan-Guizhou Plateau of Southwest China.…”

Section: Introductionmentioning

confidence: 99%

Analysis on the Influence Degree of Deformation Control Factors of Deep‐Buried Roadway’s Fractured Surrounding Rock Using Orthogonal Design

et al. 2021

Advances in Civil Engineering

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It is a complex issue to select the support structure parameters for a deep-buried roadway with fractured surrounding rock; especially when the support structure parameters need to be adjusted, the influence degree of support structure parameters on roadway deformation needs to be determined. The deformation of deep-buried roadway’s fractured surrounding rock development was investigated using multi-index orthoplan in this paper. According to the coal mine field investigation, support structure’s failure often occurs, and some need to be repaired many times. Through the roadway surrounding rock drilling, it was found that the stress of the surrounding rock was relieved, resulting in the cavity and separation of the stratum layer. The two sidewalls’ development and roof fractures are mainly tangential, and the original rock state appears only beyond 6.3∼8.2 m. The length of bolts, the row distance between bolts, the length of cables, and the row distance of U-shaped steel were selected as control factors in the multi-index orthogonal design, and roadway’s deformation values were taken as the test indexes. According to the orthoplan, nine numerical simulation schemes were designed, and FLAC3D was used for establishment. The range analysis method was used to analyze the test results. The results show that the control factors’ influence order on the total deformation of the roadway is as follows: row spacing between U-shaped steel > bolt length > cable length > row spacing between bolts, the influence order on the deformation of the roadway floor is as follows: row spacing between U-shaped steel > row spacing between bolts > bolt length > cable length, same as the left sidewall and right sidewall, and the influence order on the roadway roof’s deformation is as follows: row spacing between U-shaped steel > bolt length = cable length > row spacing between bolts, which provide a reference for the support design of deep-buried roadways with fractured surrounding rock, especially the adjustment of the supporting structure.

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Experimental study of coal fracture dynamics under the influence of cyclic freezing–thawing using shear elastic waves

Cited by 46 publications

References 39 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

Strain Rate Effect on Mechanical Properties of Cemented Backfill under Dynamic and Static Combined Loading

Analysis on the Influence Degree of Deformation Control Factors of Deep‐Buried Roadway’s Fractured Surrounding Rock Using Orthogonal Design

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