Mechanism on simulation and experiment of pre-crack seam formation in stope roof

Hu, Jianhua; Lei, Tao; Zhou, Keping; Lao, Dezheng

doi:10.1007/s11771-014-2093-2

Cited by 8 publications

(5 citation statements)

References 5 publications

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“…where n is the number of blocks divided by the plastic lines and V j is the volume of block j in m 3 .…”

Section: Mechanical Analysismentioning

confidence: 99%

“…The present status of the VCR method is summarized in four points: (i) ordinary emulsion explosives replace ammonium nitrate explosives to reduce blasting costs. The blasting charge structure evolved from a single-layer globular to a multiple-layer column [3], which significantly improved the blasting efficiency; (ii) down-upside funnel blasting was widely used in early VCR mining approaches, which had a limited free surface and low blasting efficiency. The kerf full-hole lateral blasting and kerf sectional lateral blasting techniques were subsequently invented to improve the blasting efficiency and have since been frequently used in VCR mining [4,5]; (iii) with the development of mining equipment, the cave height in deep hole mines can often reach 30 m, with some even exceeding 100 m. For instance, the cave height using the VCR method in the Anqing copper mine has reached 120 m; (iv) the application of a visual remote-control scraper transforms the stope bottom structure from a funnel and trench to being flat, which significantly reduces the mining workload and bottom pillar losses.…”

Section: Introductionmentioning

confidence: 99%

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Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

et al. 2019

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A plastic bearing calculation method for a blasting-roof is proposed to solve the problem of determining the blasting-roof thickness in deep hole mining. A mechanical analysis model for the plastic bearing was built for the typical boundary conditions of blasting-roofs. The external and internal work of the blasting-roof are equal under the plastic limit state through calculation. The limit bearing formulae of blasting-roofs under various boundary conditions were derived based on the principle of virtual work. A Vertical Crater Retreat stope was taken as the object, and the safe blasting-roof thickness was determined to be 6 m using the derived formula (considering the safety coefficient). A numerical model of stope was constructed using the Surpac-Flac3D technique, while the blasting-roof stability was simulated under different thicknesses. Variations in the simulated indexes (stress and plastic zone volume) prove that the theoretical calculations are reliable. The plastic bearing calculation method can provide a new method to determine the blasting-roof thickness in deep hole mining.

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“…where n is the number of blocks divided by the plastic lines and V j is the volume of block j in m 3 .…”

Section: Mechanical Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

et al. 2019

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“…Against this backdrop, the technique of weakening suspended roof strata was born at this moment. The existing methods including borehole pre-split blasting and directional hydraulic fracturing are verified by some actual engineering practices (Hu et al, 2014;Luo et al, 2022;Sun et al, 2021). However, it is unsuitable to use a destress blasting method in highgassy mines, which may cause gas explosion accidents.…”

Section: Introductionmentioning

confidence: 99%

Failure characteristics of thick hard roof stratum under hydraulic pre-splitting and its application in a coal mine, Dongsheng mining area

Zhu,

Li,

Teng

et al. 2024

Environ Earth Sci

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Due to the presence of the hard suspended roof, it cannot collapse naturally after being mined in a large-scale goaf. If the roof suddenly destroys without human intervention, it would cause serious disasters. In this paper, we discuss the mechanisms and applications of hydraulic fracturing in alleviating the potential for catastrophic disasters. After the fracturing crack propagation principle, we investigate the failure and stress characteristics of overburden with and without fracturing, taking a mine in Dongsheng mining area. The results show that the regulated roof suffers severe damage after fracturing, and the initial rupture distance of hard roof is reduced to 40 m or so. Additionally, the development height of water-conducting fissure zone is approximately 138.18 m. The fracturing effect can be preliminarily speculated according to fluid pressure curves. It is inferred that hydraulic fracturing point 3 has the best damage effect on the hard suspended roof. On the other hand, a common trait of overburden stress is easily observed by monitoring points, namely that the overburden stress after fracturing shows a relatively smaller value. The study provides theoretical support for the safety management of thick hard roofs, especially in the coal mines seriously affected by roof accidents.

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“…To investigate the formation mechanism of the presplit cracks, Ling proposed a fracture mechanics model of presplit blasting to analyse the effects of stress waves and quasistatic pressure of blasting gas in a blasting-induced fracturing process [11]. Based on the Holmquist-Johnson-Cook model, Hu et al built a dynamic damage model of presplit blasting and studied the evolution and formation process of the presplit cracks using numerical simulation [12]. rough numerical simulation, Cai et al reproduced the shattering induced by dynamic impact, propagation, and superposition of stress waves and crack growth driven by blasting gas in a deep-hole presplit blasting process [13,14].…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Study on the Design Method for Large‐Diameter Deep‐Hole Presplit Blasting and Its Vibration‐Isolation Effect

Xiao

Wang

Dong

2019

Shock and Vibration

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Presplit blasting can reduce vibration and back impact induced by cast blasting, thus resulting in a smooth bench slope. To design reasonable presplit blasting parameters, this research investigated the formation of presplit faces based on the explosion mechanics and revealed the cracking mechanism of presplit blasting. According to the stress distribution in the vicinity of the blast holes under the action of explosive stress waves and blasting gas, we deduced theoretical formulae for parameters including charge mass in blast holes, hole spacing, and distance from presplit blast holes to cushion holes. On this basis, a method was proposed for the design of large-diameter deep-hole presplit blasting. Field testing was conducted by setting different spacing for presplit blast holes, to monitor the blasting-induced vibration. The results showed that appropriate hole spacing can reduce the particle vibration velocity and the attenuation index of blasting-induced vibration changed slightly while the attenuation coefficient decreased significantly; the formed presplit faces were smooth and had a high half-cast factor. Finally, the reasonable hole spacing for presplit blasting, distance from presplit blast hole to the cushion hole, and the charge mass in blast holes in the Heidaigou open-pit coal mine were determined, respectively.

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Mechanism on simulation and experiment of pre-crack seam formation in stope roof

Cited by 8 publications

References 5 publications

Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

Failure characteristics of thick hard roof stratum under hydraulic pre-splitting and its application in a coal mine, Dongsheng mining area

A Preliminary Study on the Design Method for Large‐Diameter Deep‐Hole Presplit Blasting and Its Vibration‐Isolation Effect

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