Abstract: In order to investigate the dynamic failure and energy dissipation characteristics of granite-concrete composite under high temperature, dynamic compression tests were conducted using a split Hopkinson pressure bar (SHPB) with temperature (20, 200, 400, 600 ℃) and impact velocity (8, 10, 12 m/s) as variables. The results show that high temperatures significantly reduce the dynamic compressive strength of composite, and with increasing temperature, the extent of impact fragmentation intensifies. Specifically, after heating to 600 ℃, the dynamic compressive strength of composite decreases by 39.64% or more compared to 20 ℃. The increase in impact velocity leads to higher dynamic compressive strength and energy density of composite, indicating a significant strain rate effect. The average fracture particle size is negatively correlated with impact velocity and energy density, meaning higher impact velocities result in finer particle sizes. The variation of fractal dimension reveals the effect of high temperature and impact velocity on the failure mode of composite. At 600 ℃, the fractal dimension reaches its maximum value, indicating that high temperature exacerbates the internal structural damage of composite. The research results provide valuable insights for understanding and predicting the dynamic response of rock-concrete structures in high temperature environments.

Key words: granite-concrete composite, high temperature damage, dynamic compressive strength, energy dissipation characteristic, fractal dimension