Particle projection of fire-induced shotcrete spalling

As mining operations extend deeper underground, reliable support systems and workplace safety become more critical. In particular, rock bursts, blasts, and fire damage present significant challenges to the stability of deep mining operations. Shotcrete is commonly applied as ground support to mitigate the risks associated with rock falls; however, fires in underground mines can cause structural damage to the shotcrete linings. Under intense heat, shotcrete can experience spalling, where the surface breaks apart and ejects particles at varying velocities, potentially leading to support failure. This study investigates the spalling behaviour of shotcrete during fire exposure and evaluates its impact on particle projection and associated safety hazards. Advanced imaging techniques were employed to monitor changes in shotcrete during spalling events, using 3D (stereo) high-speed cameras to capture the phenomenon and motion analysis software to calculate the velocity of spalled particles.