土工基础

土工基础 ›› 2024, Vol. 38 ›› Issue (6): 975-981.

• 专题论述 • 上一篇    下一篇

循环荷载下珊瑚礁灰岩孔隙结构演化分析

贾西贝1，孟庆山2,3，吴 凯2,3，宋小龙1   

  1. （1.武汉理工大学土木工程与建筑学院，武汉 430070；2.中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室，武汉 430071；3.中国科学院大学，北京 100049）
  • 收稿日期:2023-11-22 修回日期:2024-02-25 出版日期:2024-12-31 发布日期:2024-12-20
  • 通讯作者: 孟庆山（1974-），男，博士，研究员，博士生导师，研究方向为珊瑚岛礁工程地质和力学特性等。
  • 作者简介:贾西贝（2002-），女，学士，研究方向为珊瑚岛礁工程地质特性。
  • 基金资助:
    国家自然科学基金（No.41877267, 41877260）；中国科学院大学生创新实践训练计划（课题号：Y110061Q02）

Evolution Analysis of Pore Structure of Coral Reef Limestone Under Cyclic Loading

JIA Xibei1, MENG Qingshan2,3, WU Kai2,3， SONG Xiaolong1   

  1. (1.School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070；
    2.State Key Laboratory for Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071；
    3.University of Chinese Academy of Sciences, Beijing 100049)
  • Received:2023-11-22 Revised:2024-02-25 Online:2024-12-31 Published:2024-12-20

摘要： 珊瑚礁灰岩力学行为的复杂性为“一带一路”和“海上丝绸之路”的建设带来挑战。利用基于原位CT扫描的三轴试验设备，定量评估了珊瑚礁灰岩在变幅循环荷载下的损伤演化特征。采用CT扫描和数字图像分析技术从细观上研究了珊瑚礁灰岩在不同应力状态下的结构变化。结果表明：珊瑚砾屑灰岩的割线模量随着压密和损伤的演化呈现先增大后减小的趋势，而弹性模量在压密阶段呈现减小的趋势；珊瑚礁灰岩内部孔隙的尖端在外荷载下会发生应力集中，裂纹最先在孔隙率最大且孔隙结构最复杂的区域扩展；根据裂纹在3维空间中的分布特征和切片分析可知，试样在围压为6 MPa的循环荷载下发生以剪切为主的张-剪破坏。研究结果为岛礁工程建设中围岩的安全稳定性评价提供了参考。

关键词: CT扫描, 循环加卸载, 珊瑚礁灰岩, 孔隙网络模型, 逐层面孔隙率

Abstract: The complexity of the mechanical behavior of the coral reef limestone induces challenges to the construction of the projects for the Belt and Road Initiative and the Maritime Silk Road. In this paper, the damage evolution characteristics of the coral reef limestone under the variable amplitude cyclic loading are quantitatively evaluated based on the in-situ CT scanning triaxial test equipment. The structural changes of the coral reef limestone under different stress conditions are studied by the CT scanning and the digital image analysis technique. The results show that the secant modulus of the coral gravel limestone increases first and then decreases with the pressurization and evolution of the damage, while the elastic modulus decreases in the pressurization stage. The stress concentration occurs at the tip of inner pores of the coral reef limestone under the external load, and cracks expand first in the area with the largest porosity and the most complex pore structure. According to the distribution characteristics of cracks in the three-dimensional space and the slice analysis, the specimen under the cyclic load of 6 MPa occurs the tension-shear failure mainly with the shear. The research results provide a reference for the security and stability evaluation of surrounding rock in island and reef engineering construction.

Key words: CT Scanning, Cyclic Loading and Unloading, Coral Reef Limestone, Pore Network Model, Layer-by-Layer Porosity

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