Moisture or water content in rock significantly influences blast performance through multiple mechanisms, affecting both rock fragmentation and safety outcomes. The presence of water alters rock properties, explosive efficiency, and gas dynamics during blasting, as evidenced by field studies and simulations.
Rock damage and fragmentation
Water-saturated rock exhibits lower tensile and compressive strength compared to dry rock, with studies showing up to a 20% reduction in strength (Jang et al., 2018). This weakness enhances fracturing during blasting, potentially improving fragmentation efficiency. Saturated rock transmits stress waves faster and over larger areas due to increased Poisson’s ratio and decreased Young’s modulus. This expands the blasting damage zone (BDZ), particularly in karst environments where high hydraulic pressure intensifies rock damage (Dong et al., 2023). In porous media, water content increases vibration attenuation, reducing the propagation distance of blast-induced vibrations. However, this may require higher energy input for effective fragmentation (Lu & Tao, 2023).
Explosive performance and safety risks
Prolonged water exposure degrades explosives like ANFO, leaching ammonium nitrate and reducing effectiveness. Emulsion explosives are less affected but still risk incomplete detonation if water infiltrates charges (pcm_admin, 2020). Water-saturated ground restricts explosion gas pathways, increasing confinement. This raises the risk of uncontrolled gas venting, blowouts, and flyrock, especially in confined settings like drop cuts.
In summary, water’s influence on blasting is context dependent. While it can improve fragmentation under controlled conditions, improper handling exacerbates safety hazards and reduces explosive efficiency.
Reference
Dong, Q., Liu, X., Gong, H., Luo, Y., Li, X., & Wang, L. (2023). The Damage Induced by Blasting Excavation and Seepage Characteristics of Deep Rock under High Seepage Pressure. Geofluids, 2023(1), 9159098. https://doi.org/10.1155/2023/9159098
Jang, H., Handel, D., Ko, Y., Yang, H.-S., & Miedecke, J. (2018). Effects of water deck on rock blasting performance. International Journal of Rock Mechanics and Mining Sciences, 112, 77–83. https://doi.org/10.1016/j.ijrmms.2018.09.006
Lu, G., & Tao, Y. (2023). Experimental study into the propagation and attenuation of blasting vibration waves in porous rock-like materials. Frontiers in Materials, 10. https://doi.org/10.3389/fmats.2023.1284158
pcm_admin. (2020, March 19). Assessing water influence on drop cut blasting. Quarry. https://www.quarrymagazine.com/assessing-water-influence-on-drop-cut-blasting/
