Effect of open fire on dynamic compression mechanical behavior of granite under different strain rates

Abstract

Studying the effects of open fire on the dynamic behavior of granite is of great significance to underground engineering. In this paper, an open-fire heating device was used to heat the rock to understand the effects of open fire on granites. The HS-YS4A rock acoustic wave parameter tester was used to evaluate the open-fire effects on the P-wave velocity. The results indicate that the P-wave velocity decreases sharply with the duration of the open fire in the range of 0‒10 min, after which it decreases more slowly as the fire duration increases to 60 min. Scanning electron microscopy (SEM) was utilized to observe the microscopic characteristics of the treated granite. The results show that open-fire damage promotes the formation of pores and microcracks in the rock. Dynamic mechanical experiments were conducted on the granite under different strain rates by using the split Hopkinson pressure bar (SHPB) system. The nominal dynamic compressive strength of the granite damaged by the open fire increases as the strain rate increases but decreases as the fire duration increases. These results confirm the important links among the microscopic structure, nominal dynamic compressive strength, and elasticity modulus in response to open-fire damage.