Shock Wave Interactions in Rock Blasting: the Use of Short Delays to Improve Fragmentation in Model-Scale

Johansson, Daniel; Ouchterlony, Finn

doi:10.1007/s00603-012-0249-7

Cited by 81 publications

(36 citation statements)

References 8 publications

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“…The crack propagation speed should be focussed on as an important parameter for bettering in different applications such as the determination of delaying time between blasting holes to improve excavation performance [34][35][36][37][38].…”

Section: Resultsmentioning

confidence: 99%

An Experimental Study on Determination of Crack Propagation Energy of Rock Materials under Dynamic (Impact) and Static Loading Conditions

Komurlu

2019

Hittite J. Sci. Eng.

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D etermination of the fracture toughness of rock materials can be carried out under different conditions of static and dynamic loads, by following various testing methods suggested by different researchers, standards and International Society of Rock Mechanics and Rock Engineering [1-10]. Although there are numerous researches to get deeper to identify the fracture mechanics of rock materials under cyclic (dynamic) loading and better understand the differences in behaviour of fracturing under cyclic and static loads, it is still a need to focus on more and suggest a standard testing method for determination of fracture toughness of rock materials being exposed to impact load, another type of dynamic loading induced in various rock engineering applications. Rock fracture toughness values under the impact loading condition are key parameters for various rock engineering applications such as percussion drilling, use

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Section: Resultsmentioning

confidence: 99%

An Experimental Study on Determination of Crack Propagation Energy of Rock Materials under Dynamic (Impact) and Static Loading Conditions

Komurlu

2019

Hittite J. Sci. Eng.

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“…5 (left graph); the aspect of this plot suggests a time function decreasing with the time factor down to a minimum, beyond which the function grows toward a constant value. Previous published work supports this behavior (Cunningham 2005, referring to data by Bergmann et al 1974;Katsabanis et al 2006Katsabanis et al , 2014Johansson and Ouchterlony 2013;Katsabanis and Omidi 2015), though the existence of either a minimum or a lower asymptote is somewhat controversial (Katsabanis and Omidi 2015 suggest a minimum for the median size, though not so for the 20 percentile). Consequently, a time function has been sought that decreases with increasing delay with the possibility of having a minimum.…”

Section: Model Fittingmentioning

confidence: 76%

“…The delay Unlike asteroid collisions, rock blasting is carried out in multiple loadings taking place at successive times for neighboring shots so that there is wave and crack growth interference in the rock mass between two shots in the firing sequence. The general blasting knowledge, confirmed with experimental evidence, states that fragmentation improves (i.e., the size of the fragments decreases) when time is allowed for the cracks from a hole to propagate and damage the rock before the next hole detonates (Winzer et al 1983;Katsabanis and Liu 1996;Cunningham 2005, referring data by Bergmann et al 1974;Katsabanis et al 2006Katsabanis et al , 2014Johansson and Ouchterlony 2013). The time for the cracks to propagate is a function of their velocity and that is often normalized by dividing by the P-wave velocity c P (Roberts and Wells 1954;Dulaney and Brace 1960).…”

Section: Model Fittingmentioning

confidence: 87%

A Distribution-Free Description of Fragmentation by Blasting Based on Dimensional Analysis

Sanchidrián

Ouchterlony

2016

Rock Mech Rock Eng

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A model for fragmentation in bench blasting is developed from dimensional analysis adapted from asteroid collision theory, to which two factors have been added: one describing the discontinuities spacing and orientation and another the delay between successive contiguous shots. The formulae are calibrated by nonlinear fits to 169 bench blasts in different sites and rock types, bench geometries and delay times, for which the blast design data and the size distributions of the muckpile obtained by sieving were available. Percentile sizes of the fragments distribution are obtained as the product of a rock mass structural factor, a rock strength-to-explosive energy ratio, a bench shape factor, a scale factor or characteristic size and a function of the in-row delay. The rock structure is described by means of the joints' mean spacing and orientation with respect to the free face. The strength property chosen is the strain energy at rupture that, together with the explosive energy density, forms a combined rock strength/explosive energy factor. The model is applicable from 5 to 100 percentile sizes, with all parameters determined from the fits significant to a 0.05 level. The expected error of the prediction is below 25% at any percentile. These errors are half to onethird of the errors expected with the best prediction models available to date.

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“…The charging parameter of blast holes in single blasting excavation on site is shown in Table 1. Electronic detonator is used for initiation delay to reduce the blasting vibration and improve the effect of rock fracture in many engineering experiments [18,19], and at present the minimum delay has already reached 1 ms, so I used MS1 and MS9 electronic detonators to achieve initiation delay for auxiliary blasting holes and smooth blasting holes. The plane figure of blast holes detonation network and the profile map of blast holes are shown in Figure 6.…”

Section: The Numerical Model Of Blasting Excavation Of Rock-anchored mentioning

confidence: 99%

Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

Huang

Luo

et al. 2017

Shock and Vibration

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Aiming at surrounding rock damage induced by dynamic disturbance from blasting excavation of rock-anchored beam in rock mass at moderate or far distance in underground cavern, numerical model of different linear charging density and crustal stress in underground cavern is established by adopting dynamic finite element software based on borehole layout, charging, and rock parameter of the actual situation of a certain hydropower station. Through comparison in vibration velocity, contour surface of rock mass excavation, and the crushing extent of excavated rock mass between calculation result and field monitoring, optimum linear charging density of blast hole is determined. Studies are also conducted on rock mass vibration in moderate or far distance to blasting source, the damage of surrounding rock in near-field to blasting source, and crushing degree of excavated rock mass under various in situ stress conditions. Results indicate that, within certain range of in situ stress, the blasting vibration is independent of in situ stress, while when in situ stress is increasing above certain value, the blasting vibration velocity will be increasing and the damage of surrounding rock and the crushing degree of excavated rock mass will be decreasing.

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Shock Wave Interactions in Rock Blasting: the Use of Short Delays to Improve Fragmentation in Model-Scale

Cited by 81 publications

References 8 publications

An Experimental Study on Determination of Crack Propagation Energy of Rock Materials under Dynamic (Impact) and Static Loading Conditions

An Experimental Study on Determination of Crack Propagation Energy of Rock Materials under Dynamic (Impact) and Static Loading Conditions

A Distribution-Free Description of Fragmentation by Blasting Based on Dimensional Analysis

Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

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