华南理工大学学报(自然科学版) ›› 2024, Vol. 52 ›› Issue (8): 146-158.doi: 10.12141/j.issn.1000-565X.230416

• 材料科学与技术 • 上一篇    下一篇

基于改进接触模型的类岩石材料裂纹扩展分析

丁小彬1(), 谢宇轩2, 施钰1   

  1. 1.华南理工大学 土木与交通学院,广东 广州 510640
    2.韦仕敦大学 土木与环境工程学院,加拿大 安大略 伦敦 N6A 3K7
  • 收稿日期:2023-06-16 出版日期:2024-08-25 发布日期:2023-12-27
  • 作者简介:丁小彬(1984—),男,博士,副教授,主要从事岩土工程、地下建筑结构、盾构大数据分析研究。E-mail: dingxb@scut.edu.cn
  • 基金资助:
    国家自然科学基金资助项目(41702295);广东省现代土木工程技术重点实验室项目(2021B1212040003)

Crack Extension Analysis of Rock-Like Material Based on the Improved Contact Model

DING Xiaobin1(), XIE Yuxuan2, SHI Yu1   

  1. 1.School of Civil Engineering and Transportation,South China University of Technology,Guangzhou 510640,Guangdong,China
    2.Department of Civil and Environmental Engineering,Faculty of Engineering,Western University,London N6A 3K7,Ontario,Canada
  • Received:2023-06-16 Online:2024-08-25 Published:2023-12-27
  • About author:丁小彬(1984—),男,博士,副教授,主要从事岩土工程、地下建筑结构、盾构大数据分析研究。E-mail: dingxb@scut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(41702295)

摘要:

为了探究复杂应力状态下岩体内缺陷(裂隙)的扩展与贯通机理,基于三维离散元软件(PFC3D)和改进的平行黏结模型(IPBM),模拟了双轴压缩试验中含双预制裂纹类岩石材料的裂纹扩展过程。通过逼近实验试件抗压强度、抗拉强度和弹性模量的宏观力学参数和裂纹扩展模式,调整数值模型微观参数。针对离散元模拟中的关键预制裂隙参数与围压对裂纹萌生、扩展及贯通过程的影响进行详尽的分析,结果表明:初始裂纹通常为拉伸裂纹,而次生裂纹通常为剪切裂纹,裂隙倾角主要影响初始裂纹位置;围压抑制初始裂纹,但促进次生裂纹发展;预制裂隙间的贯通裂纹与裂隙的参数和围压密切相关;围压σc > 0 MPa时,观察到两种新的剪切贯通类型(New1和New2);数值试样中微裂纹的数量主要受围压影响,与裂隙参数无明显关联;试样的裂纹起始应力、峰值应力与围压和裂隙倾角相关,与岩桥长度和岩桥倾角无关;裂纹的扩展与试样内应力分布密切相关,裂纹最先在裂隙周围的应力集中区产生。结果为后续岩石与类岩石材料的离散元模型参数校准,以及基于离散元的裂纹扩展机理研究提供了可靠参考。

关键词: 类岩石材料, 裂纹扩展, 三维离散元, 数值模拟, 双轴压缩

Abstract:

To explore the mechanism of extension and coalescence of the defect (flaw) in rocks under complex stress state, the study simulated the cracking process of rock-like material containing double pre-existing flaws in the biaxial compression test based on 3D discrete element software (PFC3D) and the improved parallel-bond model (IPBM). The microscopic parameters of the numerical model were calibrated by matching both macroscopic mechanical properties (uniaxial compressive strength, tensile strength, and elastic modulus) and cracking pattern with the laboratory experiments. The results show that: the first cracks are tensile cracks which vary with the inclination angle of flaw,and the secondary cracks are shear; the confining stress will suppress the first cracks and promote the development of the secondary cracks; the coalescence patterns of samples are closely related to the geometries of the flaw and the confining stress. Two new shear coalescence patterns (New1 and New2) can be observed at the confining stress σc > 0 MPa. The number of microcracks in the numerical sample is greatly affected by the confining stress, but not by the flaw geometries. The initial stress and peak stress of crack are correlated with confining stress and flaw inclination angle, but not with bridging length and bridging angle. The crack extension is closely related to the stress distribution in the sample, and the cracks first occur in the stress concentration area around the pre-existing flaws. The study provides a reliable reference for the subsequent calibration of discrete element model parameters and the crack extension mechanism based on discrete element.

Key words: rock-like material, crack extension, three-dimensional discrete elements, numerical simulation, biaxial compression

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