Abstract: The macroscopic mechanical behaviors of coral sand, such as high compressibility, shear and creep are closely related to the characteristics of coral particle crushing. The strain rate effect of coral particles is of great significance to study the strength and deformation characteristics of coral sand under different loading forms . The effects of loading strain rate on particle crushing strength, crushing mode and fractal dimension were studied by applying different rates of 0.1-50 mm/min on about 300 coral particles in crushing tests. The analysis results show that the crushing strength of coral grain follows the Weibull distribution law, and the characteristic crushing strength increases nonlinearly with the increasing of strain rate. Due to the increase of loading rate, the main splitting failure of coral particles appears prior to the surface grinding and local fracture, and the corresponding load-displacement curves show a transition of "multi-peak" pre- and post-peak. The fractal dimension and crushing energy density of broken coral grain are also rate-dependent and the positively linear relationship with the logarithm of strain rate indicates that the dissipated energy and damage degree develop with loading rate.

Key words: coral particle, strain rate effect, crushing strength, crushing mode, fracture energy, fractal crushing dimension