Carlota R. San Miguel has studied how cracks develop during controlled blasting to enable safer and more precise underground excavations.
24 June 2026
New insights could lead to safer and more precise blasting
When tunnels and underground excavations are blasted, the goal is to create fractures only where they are needed. Researchers at Luleå University of Technology have now investigated how different blast design parameters influence crack development in rock, providing new knowledge that could contribute to safer and more controlled excavation practices.
“Blast-induced damaging cracks affects both safety and the long-term stability of underground structures. That is why it is important to understand how they initiate and develop” says Carlota R. San Miguel, who recently defended her dissertation in Mining and Rock Engineering at Luleå University of Technology.
High-speed cameras reveal crack development
In her thesis, “On Crack Propagation Due to Blasting: Exploring Behavioral Patterns to Predict Rock Damage”, Carlota R. San Miguel investigates how cracks develop between blastholes during controlled blasting. Conducting experiments in rock-like materials together with ultra-high-speed photography and digital image correlation, the process could be studied in detail.
The results show that blasthole design has a greater influence on crack trajectories and damage distribution than the delay time between charges.
“We observed that some blast configurations promoted straighter crack paths and cleaner cuts in the rock between holes, while others generated more damage in the surrounding material” she says.
Small design changes can have major effects
The study shows how the degree of decoupling between the explosive charge and the blasthole influences how energy is transferred into the rock. Lower decoupling ratios led to earlier crack initiation and more direct crack paths between holes.
The research also investigated the use of guideholes – empty holes designed to influence crack development.
“Our experiments showed that guideholes can act as crack attractors and reduce the amount of unwanted cracks outside the intended excavation area” says Carlota R. San Miguel.
Towards a better control of underground excavations
More precise blasting can reduce damage to the surrounding rock mass. This may decrease the need for scaling and reinforcement, which has a direct impact in reducing the excavation time and material use, improving the control over excavation quality.
The findings also provide valuable input for future numerical models and simulations of blasting processes.
“The goal is to better understand the relationship between blast design and crack propagation so that blast damage can be predicted more reliably” she says.
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