| By doing caustics experiment on a variety of rock material in three-point bending test, observing the entire rock specimen impact fracture process by high-speed photography and scanning the fracture of the specimen by SEM, the same phenomenon of subcritical crack propagation was found both under the dynamic and static conditions, and the reasons for the hard success of caustics experimental on rock material and the dynamic fracture mechanism of rock material were discussed. The blasting-load reflection caustics experimental system was established, and some blasting-load caustics test on two rock-type materials were done which are artificial rock and cement paste, the blasting crack propagation behavior in the rock-type materials was studied. By theoretical analysis on the crack tip effect under the dynamic-static stress field and caustics experiment on the blasting main crack and blasting wing crack under confining pressure, the relationship between static stress field generated by the confining pressure and the blasting crack propagation behavior, and blasting crack growth law in the dynamic-static stress field were studied. With numerical simulation software DDA, the blasting model experiments were simulated to analysis the crack propagation in the dynamic-static stress filed. Also the crack tip stress distribution and crack initiation angle in the static stress field were discussed in the paper. |
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