Rock Fragmentation Under the Dynamic Loading of Underwater Shock Waves

摘要

The explosive material is used as the explosion source, and a pipe filled with water is arranged between the explosive and the cylindrical rock specimen. After the explosion, the detonation wave interacts with water and the underwater shock wave is generated in the pipe. Since the underwater shock wave attenuates with its propagation, the impact strength of the shock wave into the rock specimen can be easily adjusted by changing the length of the pipe. The free surface velocity at the end of the rock specimen and the position of cracks on the rock surface are observed by using a laser vibration meter and high-speed camera, respectively. In the case of the pipe length less than 70mm, the fragment size near the free end of the rock specimen is decreases as the pipe length increases. In contrast, in the case of the pipe length more than 70mm, the fragment size is increases. In order to understand the relationship above fracture condition and the incident underwater shock wave into the rock specimen, the numerical simulation is carried out. The 2D hydrodynamic code based on ALE finite difference scheme is employed. In the case of the fracture test with 50mm water pipe, the incident underwater shock wave into the cylindrical rock specimen has irregular pressure distribution near the shock front.