珊瑚颗粒力学特性应变率效应试验研究

珊瑚单颗粒破碎特性与珊瑚砂高压缩性、剪缩性及良好蠕变性等宏观力学行为密切相关。珊瑚颗粒的应变率效应对于不同形式荷载作用下珊瑚砂强度与变形特性研究具有重要意义。对约300颗珊瑚颗粒进行0.1～50 mm/min位移速率下的单颗粒破碎试验，探讨加载应变速率对颗粒破碎强度、破碎模式、破碎能量及破碎分形的影响。结果表明，珊瑚颗粒破碎强度服从Weibull分布规律，且特征破碎强度随应变率的提高非线性增大；随着加载速率的增大，颗粒主劈裂破坏往往先于棱角的局部碎裂和表面研磨，相应的荷载?位移曲线呈现出由峰前“多峰”向峰后“多峰”现象转变；珊瑚颗粒破碎能量密度和破碎分形维数同样具有明显的应变率效应，且均与对数应变率呈线性正相关关系，表征能量耗散和破碎程度均随加载应变率的增大而增大。

Experimental study of strain rate effects on mechanical properties of coral particles

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.