循环加载频率对饱和珊瑚砂液化特性的影响  

Influence of cyclic loading frequency on liquefaction behaviors ofsaturated coral sand

作　　者：杨铮涛 秦悠 吴琪[1,2] 陈国兴 YANG Zheng-tao;QIN You;WU Qi;CHEN Guo-xing(Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing,Jiangsu 210009,China;Civil Engineering and Earthquake Disaster Prevention Center of Jiangsu Province,Nanjing,Jiangsu 210009,China)

机构地区：[1]南京工业大学岩土工程研究所,江苏南京210009 [2]江苏省土木工程防震技术研究中心,江苏南京210009

出　　处：《岩土力学》2023年第9期2648-2656,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.52278503)。

摘　　要：人们对循环加载频率f对饱和石英砂液化特性的影响已进行大量的不排水循环试验研究,但循环加载频率f对饱和珊瑚砂液化特性的影响尚未引起重视。为探究f对饱和珊瑚砂液化特性的影响,针对中密、均等固结的饱和珊瑚砂试样,开展了f=0.01~1.00 Hz、循环主应力路径90°跳转的系列不排水循环剪切试验。试验表明:孔压比ru和广义剪应变γg的增长速率随f增大而降低,到达初始液化所需的液化次数NL随f增大而增大;不同循环加载方式引起的广义剪应变幅值γga与峰值孔压比rumax存在事实上的唯一性关系,且γga可表示为以rumax为自变量的正切函数;f的增大会减弱试样的剪胀性。引入单元体循环应力比USR作为施加于试样的循环应力水平指标,USR-NL关系曲线随f的增大而移向右上侧,不同f的USR-NL关系曲线均服从相同形式的负幂函数。这意味着饱和珊瑚砂的抗液化强度随f的增大而增大。The influence of cyclic loading frequency f on the liquefaction behaviors of saturated quartz sands during undrained cyclic laboratory tests has been investigated extensively,but rare studies reported on the effect of f on the liquefaction behaviors of saturated coral sands.To better understand the effects of the f on the liquefaction behaviors of saturated coral sand,a series of undrained cyclic shear tests is performed on isotropically consolidated,medium dense saturated specimens subjected to the 90°jump of principal stress in the range of f=0.01−1.0 Hz.For all loading patterns investigated,the growth rates of the excess pore water pressure ratio ru and the generalized shear strainγg decrease with the increase of f;the number of liquefaction NL required to cause the initial liquefaction increases with f;a unique tangent correlation function exists between the generalized shear strain amplitudeγga and the peak excess pore pressure ratio rumax(rumax is independent variable);and an increase in f weakens the dilatancy of the specimen.By introducing a unit cyclic stress ratio USR as a proxy for cyclic stress level acting on the specimen during the cyclic testing,USR versus NL curves moves to the upper right with f,a unified form of power-law function of the correlation exists between USR and NL regardless of f.This indicates that liquefaction resistance of saturated coral sands increases with f.

关 键 词：饱和珊瑚砂 液化特性 加载频率 循环加载模式 抗液化强度 

分 类 号：TU411[建筑科学—岩土工程]