Mechanical and Energy Absorption Behavior of Foam‒Aluminum Composite Rock Bolts: Insight from Mechanical Testing

Deep underground mining frequently encounters dynamic disasters such as rockbursts, where conventional support systems often fail due to insufficient energy absorption capacity. To address this issue, this paper proposes a novel thin-walled structure filled with aluminum foam (TWSF) rock bolt, which integrates a high-strength steel rod with a composite energy-absorbing cartridge. The mechanical behaviors of the aluminum foam, steel tubes, and the TWSF composite were systematically investigated through quasi-static compression and full-scale tensile tests. Results indicate that the high-density aluminum foam core (0.42 g/cm$^3$) acts as a mode controller, forcing the steel tube to deform in a high-efficiency concertina mode rather than the unstable diamond mode. This synergistic interaction resulted in a 45.24% increase in mean crushing force and a 48.74% enhancement in specific energy absorption compared to empty tubes. The full-scale TWSF bolt demonstrates a high constant working resistance of 270–280 kN and a large-deformation capacity of 200–210 mm. Compared to existing GFRP and crack-type energy-absorbing bolts, the proposed design offers a 35% higher energy absorption and approximately 50% elongation. ... mehrThese findings confirm that the TWSF bolt effectively balances high structural strength with superior ductility, providing a reliable solution for ground control in deep, high-geostress environments.