Experimental Study on the Technology of Middle Empty Hole in Parallel Hole Cut Blasting

Yang, Ren Shu; Yu, Long; Tong, Xing; Mi, Yu; Feng, Lin

doi:10.4028/www.scientific.net/amr.594-597.1314

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…Surrounding rock fracture damage is intensified by the combined action of the goaf lateral support pressure and advanced abutment pressure. The theory and technology of using a hard roof to control mining pressure is well established in the research areas of support reinforcement [25], hydraulic fracturing [26,27], blasting pressure relief [28,29], and water injection softening [30]. However, the application of deephole pre-splitting blasting technology in large pillar roadways under hard-roof and extrathick coal seam conditions remains limited.…”

Section: Introductionmentioning

confidence: 99%

Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

et al. 2021

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The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

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Section: Introductionmentioning

confidence: 99%

Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

et al. 2021

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“…Furthermore, parallel-hole cutting is a simple but efficient method for rock blasting. In the process of rock fragmentation by parallel-hole cutting, existing empty holes provide new free faces, and the stress distribution around empty holes changes, leading to a stress concentration around empty holes that results in increased rock-breaking efficiency [21], which is known as an empty-hole effect during parallel-hole cutting [22]. Extensive research efforts have been performed in the empty-hole effect [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Empty‐Hole Effect during Parallel‐Hole Cutting under Different In Situ Stress Conditions

Luo

Chen

et al. 2021

Advances in Civil Engineering

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With the progress of deep mining in mine exploitation, the effect of the in situ stress field plays a more and more significant and crucial role in rock blasting. To uncover the impact of in situ stress field on empty-hole effect during parallel-hole cutting, the distribution and the trend of changes in dynamic stress around empty hole during blasting under different in situ stress conditions are simulated based on the basic model for parallel-hole cutting using 3D finite element analysis software ANSYS/LS-DYNA and implicit-explicit analysis method. Subsequently, the law of variation in the empty-hole effect under different in situ stress conditions is determined, and the effects of horizontal and vertical stress fields are analyzed in detail. The simulation results show that the overall increase in in situ stress can facilitate compressive failure and inhibit tensile failure in the rock mass around an empty hole during blasting. When empty holes are arranged horizontally, the effect of the vertical stress field is consistent with that of the in situ stress field, while the effect of the horizontal stress field is opposite to that of the in situ stress field. With the increased stress, the inhibitive effect of the vertical stress field on tensile stress around an empty hole is remarkably stronger than that of the horizontal stress field. Finally, the numerically simulated results are verified by the theoretical calculation. This study can provide new insight and a simple but accurate numerical simulation method to investigate how the in situ stress field affects the empty-hole effect, especially in deep mining.

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“…Concerning the effect of the central hole, Xie et al [13] simulated the parallel cutting with central hole and attributed the fracture formation among adjacent cutholes to the superposition of stress wave and the tension wave reflected by the wall of the central hole. Based on the stress concentration effect of the central hole, Yang et al [14] studied the parallel cuthole cutting blasting with central holes, revealing that the central hole can reduce blasting vibration, enhance cuthole usage, and ensure blasting smoothness. Liu et al [15] performed field tests on the stress concentration effect of central hole and proved that the hole enhances rock fragmentation via the reflection of tensile waves and thereby boosts the cyclic advancement.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and Numerical Research on V‐Cut Parameters and Auxiliary Cuthole Criterion in Tunnelling

Lou

Bao

et al. 2020

Advances in Materials Science and Engineering

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This paper aims at providing a sound theoretical solution to auxiliary central hole and the cutting parameters. For this purpose, the forming mechanism of V-cut cavity for cutting blasting was performed based on the hypothetical rock breaking mechanism of V-cut blasting. A theoretical solution for increasing the critical depth of the auxiliary center cuthole and the criteria for increasing the cuthole diameter of various types of cutholes when the rock attributes, explosive properties, and cuthole dip angle are constant are proposed. (1) If charging length le < 0.75H/sin θ, no auxiliary cuthole is needed. (2) If 0.75H/sin θ < le < 0.75H/sin θ + (2∼4) × 0.1, a central vertical auxiliary hole is needed. (3) If 0.75H/sin θ + (2∼4) × 0.1 < le < 0.75(H/sin θ + Hi/sin θi), a shallow inclined hole is needed. (4) If le > 0.75(H/sin θ + Hi/sin θi), both the central vertical cuthole and the shallow inclined cuthole are needed. Meanwhile, the theoretical solution was verified by numerical modelling with ANSYS/LS-DYNA. Moreover, the field implementation of the V-cut and the auxiliary hole effectively improved the blasting effect in both efficiency and economy.

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Experimental Study on the Technology of Middle Empty Hole in Parallel Hole Cut Blasting

Cited by 5 publications

References 2 publications

Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

Numerical Simulation of Empty‐Hole Effect during Parallel‐Hole Cutting under Different In Situ Stress Conditions

Theoretical and Numerical Research on V‐Cut Parameters and Auxiliary Cuthole Criterion in Tunnelling

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