不同初始剪应力下饱和珊瑚砂的液化特性  

Liquefaction characteristics of saturated coral sand under various initial shear stresses

作　　者：秦悠 杜歆宇 马维嘉 吴琪[2,4] 陈国兴 QIN You;DU Xinyu;MA Weijia;WU Qi;CHEN Guoxing(School of Civil Engineering,University of South China,Hengyang 421001,China;Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing 211816,China;School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China;Civil Engineering and Earthquake Disaster Prevention Center of Jiangsu Province,Nanjing 211816,China)

机构地区：[1]南华大学土木工程学院,湖南衡阳421001 [2]南京工业大学岩土工程研究所,江苏南京211816 [3]南京理工大学机械工程学院,江苏南京210094 [4]江苏省土木工程防震技术研究中心,江苏南京211816

出　　处：《哈尔滨工程大学学报》2025年第2期197-204,209,共9页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(52278503,52208350)。

摘　　要：因海洋环境特殊,珊瑚砂在斜坡等地质条件下受地震或波浪作用时应力复杂。为探究初始静剪应力水平对饱和珊瑚砂液化特性的影响,利用循环三轴仪对不同相对密度D_(r)的珊瑚砂开展系列循环三轴试验。试验结果表明,饱和珊瑚砂的轴向应变ε_(a)主要表现为循环流动变形和塑性累积变形2种模式。初始剪应力抑制超静孔压u_(e)的发展,而ε_(a)=2.5%对应的超静孔压u_(e2.5%)对循环应力比CSR不敏感,建立了基于固结比K_(c)和D_(r)的饱和珊瑚砂u_(e2.5%)的经验公式。提出了考虑K_(c)影响的应力参数CSR/K_(c)^(1.5),发现在相同D_(r)下,CSR/K_(c)^(1.5)与达到ε_(a)=2.5%所需循环次数呈负幂函数关系。此外,建立了适用于不同初始剪应力下超静孔压比随循环比增长的应力孔压模型。本文研究结果不仅对初始静剪应力对饱和珊瑚砂液化特性的影响有了进一步的认识,同时对海洋基础工程建设具有一定的指导价值。Due to the unique marine environment,coral sands experience intricate stress conditions when subjected to seismic or wave in geological settings such as slopes.To investigate the impact of initial static shear stress on the liquefaction characteristics of saturated coral sand,a series of cyclic triaxial tests were conducted using a dynamic triaxial apparatus on coral sand specimens with varying relative densities(D_(r)).The test results indicate that the axial strain(ε_(a)) of saturated coral sand primarily manifests in two modes:cyclic flow deformation and plastic cumulative deformation.The initial shear stress hinders the development of excess pore water pressure(u_(e)),while u_(e2.5%)(u_(e) corresponding to ε_(a)=2.5%) shows insensitivity towards the cyclic stress ratio(CSR).Empirical equations for u_(e2.5%) in saturated coral sands based on consolidation ratios(K_(c)) and Dr have been established.A stress parameter CSR/K_(c)^(1.5) is proposed which considers the effect of K_(c),revealing a negative power function relationship with the number of cycles required to reach ε_(a)=2.5% at identical D_(r).Additionally,a stressed excess pore water pressure model applicable to the increase in excess pore water pressure ratio with cycle ratio under different initial shear stresses was developed.The findings of this study not only enhance our understanding of the influence of initial static shear stress on the liquefaction characteristics of saturated coral sands but also provide valuable guidance for marine infrastructure construction projects.Because of the special marine environment,coral sands are subject to complex stresses when subjected to earthquakes or wave action under geological conditions such as slopes.

关 键 词：饱和珊瑚砂 初始剪应力 固结比 相对密度 动三轴试验 超静孔压 轴向应变 抗液化强度 

分 类 号：TU435[建筑科学—岩土工程]