大应变条件海水浸蚀下人工胶结土动力特性研究

Effect of sea water attack on dynamic behavior of artificially cemented sand in large strain

随着海洋经济的发展,越来越多的近海设施出现,却对结构基础的耐久性提出了严峻的要求。本文将研究人工胶结土在海洋环境下长期动力特性的演化。本研究将利用动三轴试验获得不同浸蚀时间对人工胶结土的动剪切模量和阻尼比的影响。研究结果显示在海洋环境下,人工胶结土的水化反应受到严重的影响,动剪切模量比正常水环境下明显减小,而阻尼比比正常水环境下明显增大;试验还发现盐的结晶效应非常明显,尤其在干湿交替环境下,可能会对胶结作用形成破坏;在对饱和水泥土的动三轴试验发现随着浸蚀时间的增长,水泥土的抵抗液化的能力增强。结论显示水泥土改良软弱地基的能力强,也为工程设计提供参考。

The offshore and the onshore structures are emerging in China. Reliability and durability of these structures are critical for development in ocean economy. The aim of this study is to evaluate the dynamic behavior of cemented sand under seawater attack in long term. The cyclic triaxial apparatus is employed to show the evolution of shear modulus and damping ratio of the cemented sand in terms of soaking period （SP） and cement content （CC）.The results show that the cementation process is affected by the seawater to an extent compared to the sample in tap water. The shear modulus in seawater is smaller than that in tap water; while the damping ratio increases significantly as the soaking period increases and is higher than that in tap water. Also, the crystallization of salts could be clearly observed,which probably explains the evolution of dynamic behavior of cemented sand. The undrained cyclic triaxial tests show the liquefaction resistance has been enhanced with the increasing of soaking periods. Finally, it is concluded that merely slight cementation for sand can significantly improve the dynamic behavior of theground.