In order to study the dynamic failure characteristics of sandstone under the impact of a drop hammer, an acoustic emission (AE) experiment system for dynamic failure of sandstone under the impact of a drop hammer was established. The mechanical properties, energy changes, failure characteristics and AE changes of sandstone under different impact velocities were studied. The results show that the sandstone failure impact load-time history curve can be divided into 4 stages, namely, compaction stage, linear elastic stage, plastic deformation stage and post-peak development stage. Under low-speed impact, the impact load-time history curve presents a "step" characteristic. With the increase of impact velocity, the sandstone changes from rebound failure to puncture failure, and the energy absorbed by impact increases first, then decreases and then increases. The main AE frequency of sandstone damage is located in the low frequency interval (0~30kHz), which is the important characteristic frequency interval of sandstone damage under the impact of drop hammer. The research results are helpful to understand the AE variation of sandstone damage under the impact of falling hammer, and play an important role in monitoring and warning of rock burst disasters.

drop hammer impact; sandstone; dynamic failure characteristics; acoustic emission.