Controlled blasting, such as smoothwall and presplit blasting, is widely adopted in tunnel perimeter excavation and plays a significant role in reducing underbreak/overbreak and the extent of excavated damage zone, which controls the integrity and stability of excavated tunnel contour [1], [2], [3].In recent decades, tunnelling has extended into a deep level and as a …
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• Presplits are a blasting technic to aid in the creation of safe stable highwallsessential for open cut mining operations • The aim of a presplit is to create a fracture plane within the rock along …
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For the presplit blasting, the final damage of rock slope is mainly induced by presplit blasting itself. The spatial distribution characteristics of the final damage zone of two methods are compared. Two classes of damage zone could be found in smooth blasting excavation; one of them is the columnar high-degree damage zone around the slope ...
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Presplit blasting requires relatively small drill holes, between 5 to 10 cm (2 to 4 in) in diameter because its goal is to create discrete fractures, not massive breaking. However, because the small hole diameters allow the drill bit to deviate from the anticipated line more readily than larger drill diameters; the maximum depth of presplitting ...
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Presplit blasting is a commonly used technique for contour excavation that offers the advantages of eliminating overbreak and underbreak, minimizing damage to the remaining rock and reducing disturbance induced by subsequent blasts on adjacent structures. In recent years, presplit blasting has been increasingly used in rock excavation under ...
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14. With regard to the perimeter control blasting seminar tomorrow, one of the determinants is the presence of water. Water can help the formation of a presplit but can adversely affect wall stability by inducing high hydraulic pressures from production blasting.
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Presplitting is a widely used controlled blasting technique in open-pit mining, aimed at minimizing damage to the remaining rock formation and ensuring greater stability (Pomasoncco-Najarro et al ...
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• ITS DEVELOPMENT in 1958, presplit blasting has become an accepted method of obtaining essentially smooth, vertical walls in rock excavation. The usual technique has been to drill a …
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Presplit drilling and blasting are frequent excavation methods used in the mining and construction industries, but they can be challenging to implement which can also lead to inconsistent results.
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The effectiveness of the presplit blasting technique was well verified when the microstructures of the surrounding rock were investigated. The success presented in this paper does not only ...
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Presplit blasting Spacing = Hole diameter x 12 Burden = 0.5 x production blast burden (B) Uncharged length at top = 10 x D Powder factor = 0.5kg per square metre of face Do not stem holes. Fire all holes on the same delay, or in groups of ≥ 5 holes Smooth Blasting Spacing = 15 x Hole diameter (hard rock) 20 x Hole diameter (soft rock)
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Presplit blasting helps in controlling the generation of fly rock, minimising the blast-induced ground vibrations and air overpressure. Min imizing the near field blast vibrations is one of the ...
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Blasting is a major method of excavation in mining, civil construction and infrastructure projects. The integrity of the rockmass of the final wall after excavation is important for the stability and economics of the operation. Perimeter blasting achieves a planned surface of the rockmass. The pre-split is one such technique, deployed when there is no free face and, …
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Owing to the combination of blasting load and stress redistribution, crack formation at the lateral sides was inhibited during presplit blasting, while the middle side could not be sufficiently ...
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Semantic Scholar extracted view of "Effects of in-situ stress on rock cracking in presplit blasting" by Xu-dong Li et al. Skip to search form Skip to main content Skip to account menu. Semantic Scholar's Logo. Search 224,052,432 papers from all fields of science. Search ...
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Holes used for presplit blasting are lightly loaded and range from 22.5 to 25 mm (7/8 to 1 in) in diameter. A heavier charge (2 to 3 times the normal load) is used at the bottom of the borehole to ensure shearing at the floor. A common charge density is approximately 0.45 kg per square meter (0.1 lbs per square foot) of face area in the main ...
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Optimal Design of Presplit Blasting Network of Deep Concave Open-Pit Mine Slope with Heterogeneous Complex Rock Mass Yajun Chen1, Juanjuan Zhao1 2and De Cao 1 College of Mining Engineering and Geology, Xinjiang Institute of Engineering, Urumqi 830091, China 2 Beishan Open-Pit Coal Mine, Qitai County Changji Prefecture Xinjiang 831800 China
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To ensure that the mining steps of deep concave open-pit coal mines with heterogeneous complex rock masses in arid areas are safely bounded by the design requirements and form a fixed side wall ...
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When the presplit blasting is applied to rock excavation at a deep level, crack-forming difficulties are encountered due to the characteristics of high geo-stress. In this study, the influences of in-situ stress on rock cracking in presplitting are studied using theoretical and numerical methods.The transmission and superimposition of tangential stress generated by …
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the controlled blasting technique mostly used in surface mining, pre-split blasting, where reduced charges, decoupled and empty drills holes create fracture planes around the excavation mass, to ...
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Line drilling, trim blasting, buffer blasting, smooth wall blasting, air decking, and presplitting are the six controlled blasting methods that have been developed. In the mining, construction, and …
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Presplit Blasting: Presplit blasting, or presplitting, is used before production blasting to protect the final rock face from damage caused by the production blasting. Presplitting creates a fracture …
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Effective pre-splitting is a key feature of wall control blasting. Most mining operations use historical designs or rules-of-thumb for designing pre-split blasts. If productivity and safety benefits are to be gained, these methods need to be improved in order to accurately predict pre-split performance. This will become more pertinent as overburden depths increase, placing more demands on the ...
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Figure 5.3: Comparison between Presplit and Regular Blasting. Hoek (2007) Mechanics of Smooth and Presplit Blasting. In order to better understand how smooth and presplit blasting affect the final face, one needs to know the …
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• Hydraulic blasting has been explored in other areas such as small scale dimension cutting in quarries and oversize blasting • Water will also wedge into the radial fractures generated in the surrounding rock during detonation, amplifying fracture propagation • The use of water coupled blasting in an underground presplit application
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Precision Presplitting is a form of presplitting where the blast design is based on the rock properties and rock mechanics. The differences between normal presplitting and precision presplitting were discussed in the …
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Proper presplitting reduces the necessary scaling of benches to 10% of previous presplitting numbers. It increased productivity in construction blasting by more than ten-fold, allowing smaller crews to advance further on …
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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 …
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Pre-splitting can be defined as 'a technique using lightly charged, closely spaced holes to induce a fracture plane along a required design profile, which isolates the rock to be blasted from the surrounding rock mass'. The …
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Presplitting is a widely used controlled blasting technique in open-pit mining, aimed at minimizing damage to the remaining rock formation and ensuring greater stability (Pomasoncco-Najarro et al., 2022).
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