Abstract
The damage and fragmentation of rock induced by impact loading is one of typical nonlinear problems in underground engineering. Rock specimen such as rock plate was found to become invalid under impact loading. This paper presents brittle fragmentation for dynamic damage of rock plate based on the edge-on impact (EOI) test with varying impact velocities (10 m s -1 to 40 m s -1) and impact angles. High-speed camera was used to study the relation among crack initiation and propagation, impact velocity and impact angle. The patterns of fracture of the crack under impact are observed and the influence of impact angle on the growth of the crack is analyzed. The results demonstrate that only when the impact velocity is less than a critical value does a damaged zone, whose size increases with the impact velocity, appear on the edge of the sample. When the velocity exceeds the critical value, some radial cracks occur around the damaged zone and extend outward from the boundaries of damaged zone. The radial crack length and damaged zone increase with impact velocity and are influenced by the impact angle. However, at a certain velocity, the damage zone decreases and the crack length increase. It shows that there was an obvious incubation period of crack forming. According to test results, the study found that the impact velocity of this jump is about 25 m s -1 –3 m s -1 and scope of the impact resistance optimized angle is about 15 ° –30 ° .
Comments (1)
nice
posted by: mike on 02/17/2012 09:30 AM (Europe/Berlin)