首页|沉积方向对珊瑚砂动剪切模量及阻尼比的影响

沉积方向对珊瑚砂动剪切模量及阻尼比的影响

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复杂地质赋存环境下珊瑚砂具有显著的各向异性特征,颗粒的沉积方向显著影响其动力特性.对南沙岛礁珊瑚砂开展均等固结的共振柱试验,探究了珊瑚砂颗粒的沉积方向角φ(沉积面与水平面的夹角)和初始有效固结围压σ'0对其动剪切模量G和阻尼比λ的影响.在给定φ下,G随剪应变幅值γa增大而减小的速率随σ'0的增大而增加;给定 σ'0下,G随γa增大而减小的速率随φ增大呈现先减后增的趋势,φ=60°时G—γa曲线位于最下方.最大动剪切模量G0随φ的增大表现出先减后增的现象,且φ对G0的影响随σ'0的增大而降低.建立了考虑φ和σ'0影响的修正Hardin模型,预测和量测的G0值偏差小于10%.动剪切模量比G/G0—γa曲线对φ不敏感,结合修正Hardin模型和Davidenkov骨架曲线预测和量测的G值偏差小于15%.在陈国兴等(2006)提出的阻尼比经验模型中引入φ影响的修正项,预测和量测的λ值偏差小于20%.
Effect of Deposition Orientation on the Dynamic Shear Modulus and Damping Ratio of Coral Sand
Coral sand in complex geological environments exhibits significant anisotropic characteris-tics,with the sedimentation direction of the particles significantly affecting its dynamic properties.Res-onant column tests with uniform consolidation were conducted on coral sand from Nansha Islands to explore the effects of the deposition orientations(φ)(the angle between the deposition plane and the horizontal plane)and the initial effective confining pressure(σ'0)on its dynamic shear modulus G and damping ratio λ.At a given φ,the rate at which G decreased with increasing shear strain amplitude ya increased with increasing σ'0.At a given σ'0,the rate at which G decreased with increasing γa first de-creased and then increased with increasing φ,with the G-γa curve reaching its lowest position at φ=60°.Furthermore,the maximum shear modulus(G0)exhibited an initial decrease followed by an in-crease as φ increased,and the influence of φ on G0 diminished with increasing σ'0.A modified Hardin's model,which incorporated the influence of φ and σ'0,was established.The deviations between the measured and predicted G0 values were within 10%.The G/G0-ya curve was insensitive to φ,with de-viations between the measured and predicted G values by both the modified Hardin's model and Da-videnkov's skeleton curve falling within 15%.A correction term considering the influence of φ was in-troduced into the damping ratio empirical model proposed by Cheng Guoxing et al.(2006),with the deviation between the predicted and measured λ values being less than 20%.

coral sandinherent anisotropydeposition orientationdynamic shear modulusdamping ratio

徐子皓、秦悠、马维嘉、陈国兴

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南京工业大学岩土工程研究所,江苏南京 211816

南京理工大学机械工程学院,江苏南京 210094

江苏省土木工程防震技术研究中心,江苏南京 211816

珊瑚砂 原生各向异性 沉积角度 动剪切模量 阻尼比

国家自然科学基金国家自然科学基金

5227850352208350

2024

防灾减灾工程学报
中国灾害防御协会 江苏省地震局

防灾减灾工程学报

CSTPCD北大核心
影响因子:0.529
ISSN:1672-2132
年,卷(期):2024.44(3)
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