摘要
为了满足南沙珊瑚岛礁及近岸军事与民事功能设施建设对珊瑚砂动力特性参数的急迫需要,系统而深入地研究珊瑚砂动力变形特性已是一项紧迫的科学任务。利用共振柱对取自南沙群岛某岛礁的珊瑚砂开展了系列动剪切模量和阻尼比特性试验研究,探究相对密度Dr、初始有效围压σm’、细粒含量FC对南沙珊瑚砂动力变形的影响。试验结果表明:反映σm’对最大动剪切模量Gmax影响程度的应力指数n是与土性相关的常数;结合文献中3类砂类土的Gmax试验数据,发现随等效骨架孔隙比e*sk的增大各砂类土的应力修正最大动剪切模量Gmax/(σm’/Pa)n单调减小,且两者呈现较好的幂函数关系;在同一应变水平下,珊瑚砂动剪切模量G随FC的增大而减小,随Dr、σm’的增大而增大;当剪应变γ<10-4时,FC、Dr与σm’对阻尼比影响不大,而γ>10-4时,FC、Dr与σm’对阻尼比影响显著;Dr与σm’对动剪切模量比G/Gmax影响不明显;而当0%≤FC≤30%时,随FC增大G/Gmax-γ衰减曲线不断下降,给出了珊瑚砂Davidenkov模型拟合参数A、B的建议值,且发现参考剪应变γ0随FC线性减小。
In order to meet the urgent need for the cyclic characteristic parameters of coral sand in the proper engineering analysis of both military and civilian function facilities located in Nansha reefs and offshore marine areas,it is an important and emergent scientific task to study the dynamic deformation characteristics of the coral sand of the Nansha Islands in China.A series of resonance column tests are carried out on the saturated coral sand specimens from Nansha Islands.The aim of the tests is to investigate the effects of relative density Dr,initial effective confining pressureσm’and fines content FC on the dynamic deformation characteristics of the specimens.The test results show that the stress exponent n,reflecting the rates of Gmax increment due to the enhancement ofσm’,presents a soil-specific constant.Synthesising the test data here and from three saturated sandy soils in the literatures,it is found that the stress-corrected maximum shear modulus Gmax/(σm’/Pa)n decreases monotonically with the increase of the equivalent skeleton void ratio e,and a power relationship between Gmax/(σm’/Pa)n ande*sk is then obtained.At the same strain level,the dynamic shear modulus G of the coral sand decreases with the increase of FC,and increases with the increase of Dr andσm’.FC,Dr andσm’have few effects on the damping ratio when the shear strainγ<10-4,but have a significant effect on the damping ratio whenγ>10-4.Dr andσm’have no obvious influences on the dynamic shear modulus ratio G/Gmax.When 0%≤FC≤30%,the G/Gmax-γattenuation curve continues to decline with the increase of FC.The recommended values of fitting parametes A and B of the Davidenkov model for the coral sand are given,and it is found that the reference shear strainγ0 decreases linearly with FC.
作者
吴琪
杨铮涛
刘抗
陈国兴
WU Qi;YANG Zheng-tao;LIU Kang;CHEN Guo-xing(Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing 210009,China;Civil Engineering and Earthquake Disaster Prevention Center of Jiangsu Province,Nanjing 210009,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2022年第8期1386-1396,I0003,I0004,共13页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(52008206)
国家重点发展计划项目(2018YFC1504301)。
关键词
珊瑚砂
细粒含量
最大动剪切模量
动剪切模量比
阻尼比
coral sand
fines content
maximum dynamic shear modulus
dynamic shear modulus ratio
damping ratio
