Blasting Failure Characteristics of Rock Specimens under In-Hole Layered Column Charge
Authors: CHENG Bing, YE Fu, WANG Quan, CHENG Yangfan, ZONG Qi, XU Ying, WANG Mengxiang, LI Junhao
To improve rock fragmentation in open-pit deep-hole blasting, an in-hole layered column charge configuration was designed. Small-scale blasting tests on sandstone specimens were conducted under continuous and layered column charges to capture the failure process and final fragmentation. DEM-PBM coupled simulations visualized the dynamic fracture evolution and validated the experimental observations. Results show that under continuous charge, the top quarter of the specimen developed only a single blast-induced crack, splitting it into two parts, with horizontal fragment velocity of 2.0 m·s⁻¹ and a maximum block size of 9.0 cm. In contrast, layered charge produced multiple cracks in the top quarter, fragmenting it into smaller pieces, increasing horizontal velocity to 7.0 m·s⁻¹, and eliminating blocks larger than 5.0 cm. Simulations confirmed these trends, with maximum block size reduced from 8.8 cm to below 5.0 cm and velocity reaching 6.8 m·s⁻¹, closely matching experiments. Field trials in an open-pit coal mine overburden blasting demonstrated that layered charge reduced the boulder yield from 48.1% to 5.6%, significantly improving fragmentation. The findings confirm the practical effectiveness of in-hole layered column charge in enhancing rock breakage in deep-hole bench blasting.
