摘要
对南海饱和珊瑚砂进行了4类不同加载模式的不排水动三轴试验,研究了不同相对密度Dr和平均有效围压σ’0下加载第一周的动剪切模量比G1st/G0与剪应变幅值γa的关系,G1st/G0受Dr的影响很小,随σ’0的增大而增大。由于分级加载过程中土体结构与相对密度发生改变,在γa>3×10^-4时,应变控制的分级循环加载获得的G1st/G0-γa曲线位于等应变幅值循环加载获得的G1st/G0-γa曲线的上方。结合两类试验结果,给出了饱和珊瑚砂的G1st/G0-γa模型。基于弹性应变能理论,提出了可以描述土体损伤状态的状态参数Pd(damage parameter),探究了不同加载模式下动剪切模量比G/G0随土体损伤状态参数Pd的发展规律。在双对数坐标中,同一应变幅值下的(1-G/G0)-Pd可用直线表示,其斜率与应变幅值γa和历史加载过程中的最大应变幅值γa,max有关。结合G1st/G0-γa和G/G0-Pd关系,给出了可以同时反映应变幅值和破坏状态影响的珊瑚砂动剪切模量预测模型。
Four series of cyclic triaxial tests with different loading forms are conducted on saturated coral sand from Nansha Islands.The relationships between shear modulus ratio G1st/G0 of the first loading cycle and shear strain amplitude γa under different relative densities Dr and effective confining pressures σ'0 are studied.Dr shows no influence on G1st/G0, and G1st/G0 increases with the increasing σ'0 .When γa is larger than 3×10^-4, the G1st/G0 -γa curves obtained from the strain-controlled multistage loading tests (UMγ-CTX) are higher than those obtained from strain-controlled single-stage loading tests (USγ-CTX) because of the change of the soil structure and the relative density during the reconsolidation process of UMγ-CTX.A new damage parameter Pd is proposed based on the elastic strain energy theory, and the relationships between shear modulus ratio G/G0 and damage parameter Pd under different loading forms are studied.The (1-G/G0)- Pd curves are almost linear in the log-log coordinate, and the slopes are dependent on the shear strain amplitude a ? and the maximum shear strain amplitude a,max γ.Based on the G1st/G0 -γa and G/G0 - Pd relationships, a new G/G0 prediction model is proposed to predict the shear modulus of coral sand considering the effect of coupled shear strain amplitude and damage state.
作者
梁珂
陈国兴
王彦臻
秦悠
LIANG Ke;CHEN Guo-xing;WANG Yan-zhen;QIN You(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
2019年第10期1863-1871,共9页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51678299)
国家重点研发计划项目(2017YFC1500403)
江苏省研究生科研计划项目(KYCX18_1057)
关键词
珊瑚砂
动剪切模量
弹性应变能
损伤状态
动三轴试验
coral sand
dynamic shear modulus
elastic strain energy
damage state
cyclic triaxial test
