The Use of Lagrange Diagrams in Precise Initiation Blasting. Part I: Two Interacting Blastholes

Roßmanith, H. P.

doi:10.1076/frag.6.1.104.8854

Cited by 30 publications

(12 citation statements)

References 6 publications

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“…Rossmanith (2002) proposes that maximising stress-wave interaction within the body of a blast should maximise the amount of fracturing occurring, at both the micro-and macro-scale. Various field researchers (e.g.…”

Section: Fragmentation Controlmentioning

confidence: 99%

Seed wave modelling applications for fragmentation, damage and environmental impact control

McKenzie¹

2012

Blasting in Mining - New Trends

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Modern mine productivity places a very strong focus on achieving high levels of control over fragmentation, wall control (damage to excavation limits) and environmental impact. The introduction and extensive use of electronic initiation heightens the focus of each one of these blasting outcomes, though systems to permit optimisation are not readily or widely available, and are seldom used in any routine manner in the mining industry. Seed wave modelling, in conjunction with electronic initiation, enables blasting engineers to identify optimum timing configurations for any type of blast, with respect to each of the three mentioned blasting outcomes. Fragmentation, either in the body of the blast or in the stemming zone of blasts, can be increased substantially by optimising timing from the point of view of maximising induced stresses within the rock mass, enabling quantification of a fragmentation index for specific vertical bench sections. Damage, either in the bench batter behind a limits blast, or in the underlying berm, can similarly be minimised by careful delay timing, often more effectively than by costly reduction of blasthole diameter, enabling definition of a Probability of Damage curve. Environmental vibration impacts, either in the medium-field as an impact on vibration-sensitive slopes or mine sectors, or in the far-field as an impact on nearby occupied structures, can also be minimised by careful selection of delay timing. This paper presents the use of seed wave modelling as an everyday tool to enable blasting engineers to make engineering-based decisions regarding the delay timing which will bring maximum control over these blasting impacts.

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Section: Fragmentation Controlmentioning

confidence: 99%

Seed wave modelling applications for fragmentation, damage and environmental impact control

McKenzie¹

2012

Blasting in Mining - New Trends

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“…ird, the stress wave decays as the distance increases. Tensile fracturing will only occur if the wave amplitude has exceeded a certain threshold [16]. Fourth, based on an example of linear elastic fracture mechanics, Exadaktylos [17] demonstrated that a crack close to more than one free surface has a higher stress intensity than a crack close to one free surface with the same internal pressure.…”

Section: E First Crack On the Bevel Surfacementioning

confidence: 99%

Full‐Field Strain Characterizations and Fracture Process of Rock Blasting Using a Small‐Scale Double‐Hole Bench Model

Yang

Liu

et al. 2020

Advances in Civil Engineering

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A small-scale double-hole bench model is designed with granite to study the fracture mechanism of rock blasting. By combining high-speed camera and digital image correlation, the full-field strain characterization and fracture process of the specimen bevel surface are investigated. The preliminary test results show that the strain concentration zone corresponds to the crack propagation location, and digital image correlation can well detect the crack propagation. In addition, through observing the crack propagation pattern on the specimen bevel surface, it can be seen that the fracture of the specimen is caused by the dominant horizontal crack and the dominant vertical crack, and the generation of the dominant horizontal crack takes precedence over that of the dominant vertical. Finally, the measurements of two-dimensional digital image correlation and three-dimensional digital image correlation are discussed.

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“…The objective of this study is to investigate the effect of stress wave interaction between blast holes with a single free surface. Compared to the 2D model with the assumption of an infinitely long charge length presented in the previous studies of Rossmanith [ 9 ] and Yi et al [ 23 ], the stress wave interaction in a 3D model of short-delay blasting with a single free surface is much more complicated. As seen in Fig 2 , the existence of a free surface would lead to additional superposition of the reflected stress wave from the first blast hole with the incoming stress wave from the second blast hole ( Fig 2C ), which affects the rock fragmentation process.…”

Section: Introductionmentioning

confidence: 97%

“…Another controversial reason is that since short-delay blasting is possible with the increase of initiating accuracy for detonators, stress waves interaction between adjacent blast holes does occur and plays an important role in rock fragmentation [ 8 – 10 ]. Rossmanith [ 9 ] and Rossmanith and Kouzniak [ 10 ] constructed a 2D model to study the possible area of shock wave interaction and showed how a positive effect of shock wave interaction could be achieved in an charge column with infinitely length. Chiappetta [ 11 ] indicated that short-delay internals such as 2 ms, which was short enough for stress waves from adjacent blast holes to interact with each other, was beneficial to improve fragmentation.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of stress wave interaction in short-delay blasting with a single free surface

et al. 2018

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It is generally believed that stress wave superposition does occur and plays an important role in cutting blasting with a single free surface, in which explosive columns of several blast holes with short spacing are simultaneously initiated. However, considering the large scatter of pyrotechnic delay detonators that are used in most underground metal mines in China, the existence of stress wave superposition and the influence of this effect on rock fragmentation are questionable. In the present study, the stress wave interaction in short-delay blasting with a single free surface was studied through the use of the LS-DYNA code. Stress waves induced by two blast holes blasting with different delays were compared with the single blast hole case, and the effects of delay time, detonating location and spacing on stress wave superposition were investigated. The numerical results showed that for blast holes with a 1 m spacing, stress wave interaction only occurs when the delay time is 0 ms and does not occur for blasting with delays of more than 1 ms. An increase in the duration of a stress wave via optimizing the detonation location does not improve the stress wave interaction. For a 1 ms delay, stress wave superposition only occurs when the spacing is more than 4 m, which is a rare case in practice. The results indicated that the occurrence of stress wave superposition for blasting with a single free surface is strictly limited to conditions that would be difficult to achieve under the existing delay accuracy of detonators. Therefore, it is unrealistic to improve fragmentation via the stress wave interaction in field blasting. Furthermore, the numerical results of the stress wave interaction also show that there would be a great potential to reduce the hazardous vibrations induced by short-delay blasting by using electronic detonators with better control of delays in an order of several milliseconds.

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The Use of Lagrange Diagrams in Precise Initiation Blasting. Part I: Two Interacting Blastholes

Cited by 30 publications

References 6 publications

Seed wave modelling applications for fragmentation, damage and environmental impact control

Seed wave modelling applications for fragmentation, damage and environmental impact control

Full‐Field Strain Characterizations and Fracture Process of Rock Blasting Using a Small‐Scale Double‐Hole Bench Model

Numerical simulation of stress wave interaction in short-delay blasting with a single free surface

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