Response and impact mechanism of rock bolt under lateral dynamic impact load

In order to study the dynamic mechanical properties of rock bolt under impact load,the mechanical proper- ties of five different material rock bolts were tested. Lateral impact resistance test on the rock bolts was carried out using a free-fall hammer impact test device to evaluate the dynamic response of the rock bolts. The lateral impact test was performed with five different impact heights to obtain the dynamic impact response curve,the bolt axial strain-time curve,and the force-displacement-time curve at the impact point. The study found that under the condition of the same impact energy,the higher the impact absorbed energy of rock bolt,the smaller the impact peak load. Impact reaction time increases as the impact height decreases. The higher the impact absorbed energy of the rock bolt,the greater the peak strain and residual strain. The distinct differences in the impact peak load and the maximum displacement were observed among the different rock bolts. The larger the peak strength and the maximum displacement,the higher the breaking energy. It was also found that controlling the material content of beneficial and harmful elements can improve the impact resistance of the rock bolts. In addition,the microstructure and organization of the rock bolt fracture profiles were analyzed and it was found that the greater the impact absorbed energy of the rock bolt,the higher the grain size level.