The law of blast stress wave propagation and fracture development in soft and hard composite rock

Ding, Xiaohua; Yang, Yuqing; Zhou, Wei; An, Wen; Li, Jinyu; Manda, Ebelia

doi:10.1038/s41598-022-22109-z

Cited by 6 publications

(3 citation statements)

References 34 publications

(29 reference statements)

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“…Recent research addresses the topic of delays in blasting. [19,20] consider crack growth: they state that delayed initiation provides enough timing for preconditioning the surrounding rock for the neighboring blasthole. [21] considered the initiation sequence of a row of holes: one-directional initiation vs. initiating the row from the extremities towards the center: the order of ignition of blast holes is from the center to both ends of the row of blast holes can produce a more uniform size of fragmented rocks.…”

Section: Discussionmentioning

confidence: 99%

The Role of Delays in the Performance of Blasting

Seccatore,

Vigna,

Marin

et al. 2024

Preprint

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When researching rock blasting, the design parameters used for the analysis are usually the ge-ometric and charging ones. This study is based on a different approach, and focuses on the effect of timing, in specific the role of delays in the initiation sequence. The data come from the results of full-scale blasts. The experimental setting and location allowed to consider all parameter other than the number of delays as a constant. The experimental results are analyzed relating the delay var-iables to fragmentation and KPIs of downstream operations. It is shown how increasing the number of delays per unit of blasted rock and reducing simultaneous adjacent holes produces finer fragmentation, reduces the amount of fines, facilitates the secondary operations and reduces the risk of flyrock.

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Section: Discussionmentioning

confidence: 99%

The Role of Delays in the Performance of Blasting

Seccatore,

Vigna,

Marin

et al. 2024

Preprint

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“…Damage zones around a single-hole blast have been studied by several researchers experimentally and using numerical models [3][4][5][6][7][8]. These studies observed that several factors influence the extent of damage zones, the main ones being the explosive strength (determined using the velocity of detonation (VOD), density, and detonation pressure) and rock mass strength (uniaxial compressive strength, tensile strength, Young's modulus, and Poisson ratio).…”

Section: Introductionmentioning

confidence: 99%

The Influence of Explosive and Rock Mass Properties on Blast Damage in a Single-Hole Blasting

Dotto,

Pourrahimian

2024

Mining

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In rock blasting for mining production, stress waves play a major role in rock fracturing, along with explosive gases. Better energy distribution improves fragmentation and safety, lowers production costs, increases productivity, and controls ore losses and dilution. Blast outcomes vary significantly depending on the choice of the explosive and the properties of the rock mass encountered. This study analyzes the effects of rock mass and explosive properties on blast outcomes via numerical simulation using data from the case study, and later validates the simulation results from the field blast fragmentation. The findings suggest that, for a given set of rock properties, the choice of explosive has a major influence on the resulting fragmentation. Strong explosives (high VOD and detonation pressure) favor large fracture extents in hard rocks, while weaker explosives offer a better distribution of explosive energy and fractures. The presence of rock structures such as rock contacts and joints influences the propagation of stress waves and fractures depending on the structures’ material properties, the intensity and orientations, and the direction and strength of the stress wave. When the stress wave encounters a contact depending on its direction, it is enhanced when traveling from soft to hard and attenuates in the opposite direction. The ability of the stress wave to cause fracturing on the opposite side of the contact depends on the intensity of the transmitted wave and the strength of the rock. Transmitted wave intensity is a function of the strength of the incident wave and the impedance difference between the interface materials. The presence of joints in the rock mass affects the propagation of the stress wave, mainly depending on the infill material properties and the angle at which the stress wave approaches the joint. Less compressible, higher stiffness joints transmit more energy. More energy is also transmitted in the areas where the stress wave hits the joint perpendicularly. Joints parallel to the free face offer additional fracturing on the opposite side of the joint. Other parameters, such as the joint width, continuity, fracture frequency, and the distance from the charge, enhance the effects. To achieve effective fragmentation, the blast design should mitigate the effect of variability in the rock mass via explosive selection and pattern design to ensure adequate energy distribution within the limits of geometric design.

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“…Layered composite rock masses with multiple parallel joints are present in many natural strata 1–4 . When the stress wave propagates through the layered composite rock masses, the wave not only undergoes direct transmission but also undergoes multiple reflections between parallel joints 5–8 .…”

Section: Introductionmentioning

confidence: 99%

The effects of joint spacing on transmission characteristics of stress waves through layered composite rock masses

Fan,

Shi,

Wang

et al. 2023

Num Anal Meth Geomechanics

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The effects of joint spacing on the transmission characteristics of stress waves through layered composite rock masses were investigated. First, a model of layered composite rock masses containing multiple parallel joints with different media in front of and behind the joints was introduced to study multiple reflections between joints. Second, wave transmission through layered composite rock masses was investigated and compared with wave transmission through traditional layered homogeneous rock masses. Finally, the effects of joint spacing and wave impedance ratio on particle velocity transmission coefficient were discussed. The results indicate that for wave propagation through rock masses with the same joint spacing, the onset time and amplitude of the transmitted wave in layered composite rock masses are smaller than those in layered homogeneous rock masses. For wave transmission through rock masses with the same nondimensional joint spacing, the onset time of the transmitted wave in the layered composite rock masses is similar to that in the layered homogeneous rock masses, while the amplitude of the transmitted wave in the layered composite rock masses is smaller than that in the layered homogeneous rock masses. In addition, the particle velocity transmission coefficient first increases and then decreases to be constant as the joint spacing increases, while it continues to increase as the wave impedance ratio increases for wave transmission through both layered composite rock masses and layered homogeneous rock masses.

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The law of blast stress wave propagation and fracture development in soft and hard composite rock

Cited by 6 publications

References 34 publications

The Role of Delays in the Performance of Blasting

The Role of Delays in the Performance of Blasting

The Influence of Explosive and Rock Mass Properties on Blast Damage in a Single-Hole Blasting

The effects of joint spacing on transmission characteristics of stress waves through layered composite rock masses

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