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中国南海吹填岛礁原状钙质砂蠕变特征初探 被引量:1

Preliminary study on the creep characteristics of calcareous sand from reclaimed coral reef islands in South China Sea
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摘要 南海岛礁吹填工程是我国的战略性工程,岛礁顶部的吹填陆域主要由珊瑚钙质砂组成。已有的研究表明,珊瑚钙质砂在恒定荷载长期作用下会产生蠕变变形。作为各种岛礁结构物的地基材料的钙质砂,其长期蠕变行为会对岛礁结构物的长期沉降变形产生影响。因此,研究南海岛礁珊瑚钙质砂的长期蠕变特征具有重要的工程意义。对取自我国南海某岛礁的原状级配珊瑚钙质砂开展了室内饱和三轴排水蠕变试验(围压100 kPa),研究其长期蠕变特征。试验结果表明,珊瑚钙质砂的蠕变为衰减型稳态蠕变,不同应力条件下的蠕变–时间曲线在双对数坐标中均为直线,可以采用幂函数进行描述;且同一密实程度的钙质砂在不同偏应力作用下蠕变直线族基本平行,直线斜率与偏应力量级无明显关系。钙质砂蠕变阶段的体积变化趋势受蠕变之前试样的体积收缩是否充分完成控制。研究发现Mesri蠕变数学模型可以很好地描述珊瑚钙质砂的应力–应变–时间关系,最终的蠕变变形和应力水平q/(σ1-σ3)f呈现出高度线性正相关关系。试验前后颗粒筛分发现,低围压下钙质砂蠕变过程中颗粒破碎极不明显,表明珊瑚钙质砂在低围压条件下其蠕变变形主要是由颗粒间滑移、错动、重排列引起。 The construction of a series of reclamation islands on coral reefs in South China Sea is a strategic project of China. These reclaimed lands on the top of coral reefs mainly consist of calcareous sand. Previous studies have confirmed that coral calcareous sand could generate creep deformation under long term constant loading. As the foundation material of all kind of structures built on reclaimed coral reefs,the creep behavior of calcareous sand will definitely affect the long-term subsidence of these structures. Therefore,it is highly necessary to investigate the long-term creep characteristics of the coral calcareous sand from South China Sea. A series of tri-axial drained creep tests were performed with the samples from a coral reef island in South China Sea under the confining pressure of 100 kPa to investigate the creep characteristics of calcareous sand. The experimental results indicate that the creep of the calcareous sand is an attenuated and steady type. The curves between the creep strain and the time in double logarithmic coordinates are all straight lines under different stress conditions and can be described by a power function. It is found that,in the case of the same dry density of the calcareous sand, these straight lines corresponding to different creep deviatoric stresses are basically parallel with each other and the slopes of the straight lines are hardly affected by the creep deviatoric stress. It is also revealed that the trend of volume change of calcareous sand samples at the creep stage is mainly controlled by the process of that the volume contraction of calcareous sand samples is finished or not under shearing before the beginning of the creep stage.The research results show that Mesri creep model can effectively describe the stress-strain-time relation of the coral calcareous sand and that the final creep strain of the calcareous sand is highly linearly related to the stress level q/(σ1-σ3)f. Particles gradation tests before and after the creep test indicate that the creep of the ca
作者 叶剑红 曹梦 李刚 YE Jianhong;CAO Meng;LI Gang(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;School of Resource and Environmental Engineering,Wuhan University of Technology,Wuhan,Hubei 430070,China;School of Civil Engineering,Xijing College,Xi'an,Shaanxi 710123,China)
出处 《岩石力学与工程学报》 EI CAS CSCD 北大核心 2019年第6期1242-1251,共10页 Chinese Journal of Rock Mechanics and Engineering
基金 中国科学院战略性先导科技专项(A类)子课题一结构物安全与服役性能(XDA13010202).
关键词 土力学 珊瑚钙质砂 三轴蠕变试验 蠕变特征 蠕变模型 南海岛礁吹填工程 soil mechanics coral calcareous sand triaxial creep test creep characteristics creep mathematical model coral reef reclamation project in South China Sea
作者简介 叶剑红(1981-),男,博士,2006年毕业中国地质大学(北京)土木工程工业,现任教授,上要从事流体-结构物-海床地基相互作用(FSSI)、海洋岩土工程、南海岛礁结构物波浪、地震稳定性等方面的研究工作。E-mail:yejianhongcas@gmai1.com.
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