EXPERIMENTAL STUDY OF DYNAMIC MECHANICAL PROPERTIES OF ROCKS

To understand the dynamic mechanical properties of rocks,a series of dynamic shock compression tests were carried out by using φ 50 mm Hopkinson pressure bar apparatus,with strain rate range from 25.4 to 193.4 s-1. Wave shaping technique was used to smooth pulse load;dynamic stress-strain curves were obtained. Experiment data show that the strength of rock has an obvious strain rate effect. The value of strength increases with increasing strain rate. Compared with static strength of 120 MPa,the maximum dynamic strength is enhanced to 365 MPa at strain rate of 193.4 s-1. With the increase in dynamic load,specimen experiences a process of the generation of internal damage,micro flaw,macro crack,fracturing to nubbins and crushing to pieces. The results are valuable for military structure design.