钙质砂与钢界面循环剪切刚度与阻尼比的试验研究

钙质砂与钢界面的动力响应对岛礁地质条件下结构物基础的安全与稳定具有重要意义。基于界面环剪仪，开展了一系列钙质砂?钢界面循环剪切试验，探究了法向应力、剪切位移幅值和粒径大小对界面剪切刚度和阻尼比的影响，并与石英砂进行了对比。研究结果表明：法向应力和剪切位移幅值对界面剪切刚度和阻尼比起控制作用；法向应力的增大导致界面剪切刚度增大、阻尼比降低；剪切位移幅值的增大，则导致剪切刚度近似呈反比降低，而阻尼比近似呈对数增大；对于均一粒径的钙质砂，存在着分界粒径，使其剪切刚度和阻尼比的变化规律呈现显著区别；石英砂粒径较大时，其界面剪切刚度和阻尼比与钙质砂明显不同，而粒径较小时两类砂表现出类似的剪切刚度和阻尼比特性。

Experimental study of cyclic shear stiffness and damping ratio of carbonate sand-steel interface

The dynamic response of carbonate sand-steel interface is of great significance to the safety and stability of foundations in reef islands. Based on the interface ring shear apparatus, a series of cyclic shear tests on the interface between carbonate sand and steel was carried out. The effects of normal stress, cyclic amplitude and particle size on the interface shear stiffness and damping ratio were investigated, and compared with quartz sand. The results show that normal stress and cyclic amplitude have significant effects on the interface shear stiffness and damping ratio; the increase of normal stress level increases the shear stiffness and decreases the damping ratio; the increase of cyclic amplitude leads to an approximate inverse reduction of shear stiffness and an approximate logarithmic increase of damping ratio; for carbonate sand with a uniform particle size, a critical particle size exists that results in a significantly different interface shear behavior. When the particle size of quartz sands is large, the shear stiffness and damping ratio are different from those of carbonate sands. But, if the particle size is small, the shear stiffness and damping ratio of these two sands are almost the same.