Dynamic compression and failure behavior of limestone under surface-constrained energy transmission

As an essential material in various construction and mining projects, the deformation and failure of rocks directly affect the safety and efficiency of the project. Energy transmission plays a crucial role in the deformation and failure process of rocks, and local energy constraints are often used to improve rock-breaking efficiency. This study proposed an energy constrained component combined with split Hopkinson compression bar (SHPB) system to investigate the dynamic failure characteristics and energy conversion laws of limestone under constrained impact conditions. The results demonstrate that constrained energy transmission significantly alters rock failure mechanisms. The peak stress reduces to 20–30% of ordinary impact values, while dynamic deformation modulus decreases by more than 50%. The constrained impact stress weakens the influence of loading rate on dynamic parameters, but due to concentrated energy absorption, the energy conversion efficiency increased to 86–91%, enhancing fragmentation control. Fractal analysis of fragments shows that with the increase of impact velocity, the fractal dimension of the fragments shows an exponential growth trend but slows down, indicating that the reduction of rock fragment size is limited. These reflect that constrained energy transmission optimizes energy utilization and mitigates uncontrolled fragmentation, offering practical implications for optimizing rock breakage, enhancing support design resilience, and mitigating dynamic hazards in deep mining.