岩土力学 ›› 2021, Vol. 42 ›› Issue (11): 3191-3201.doi: 10.16285/j.rsm.2021.0123

• 数值分析 • 上一篇    

间断级配砂土渗流侵蚀现象的计算 流体力学-离散元耦合模拟

李伟一1, 2,钱建固1, 2,尹振宇3,周闯2   

  1. 1. 新疆大学建筑工程学院,新疆 乌鲁木齐 830047;2.同济大学 岩土及地下工程教育部重点实验室,上海 200092; 3. 香港理工大学 土木与环境工程系,香港
  • 收稿日期:2021-05-13 修回日期:2021-08-23 出版日期:2021-11-11 发布日期:2021-11-12
  • 通讯作者: 钱建固,男,1972年生,博士,教授,博士生导师,主要从事土力学的研究工作。E-mail: qianjiangu@tongji.edu.cn E-mail:1live@tongji.edu.cn
  • 作者简介:李伟一,男,1994年生,博士研究生,主要从事砂土渗流侵蚀、隧道开挖面稳定方面的研究工作。
  • 基金资助:
    国家自然科学基金资助项目(No. 52178345);中央高校基本科研业务费专项资金资助(No. 22120190220);苏州河段深层排水调蓄管道系统工程试验段监测技术验证与分析模型研究项目。

Simulation of seepage erosion in gap graded sand soil using CFD-DEM

LI Wei-yi1, 2, QIAN Jian-gu1, 2, YIN Zhen-yu3, ZHOU Chuang2   

  1. 1. College of Architecture and Civil Engineering, Xinjiang University, Urumqi, Xinjiang 830047, China; 2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China; 3. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
  • Received:2021-05-13 Revised:2021-08-23 Online:2021-11-11 Published:2021-11-12
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (52178345), the Fundamental Research Funds for the Central Universities Project (22120190220) and Fund for Research on the Monitoring Technology and the Analytical Model of the Shanghai Deep Drainage System.

摘要: 渗流侵蚀会导致土体中土颗粒的随水流流失,改变土体力学和水力特性,工程中常引起土石坝的变形甚至破坏。利用流体力学-离散元耦合方法(CFD-DEM),针对广泛存在于坝基、土石坝滤芯以及油气井反滤层中的间断级配砂土,对其级配进行合理简化后研究其在水力作用下的渗流侵蚀特性。通过8组模拟向上渗流试验研究了水力梯度、试样所受围压以及细粒含量对间断级配砂土渗流侵蚀过程的影响。试验中监测了细粒流失质量、细粒流失率、土表位移、微观组构变化等宏微观现象,并与既往室内试验进行了对照验证。同时,对渗流前后土体进行了排水剪切试验,研究渗流侵蚀对土体抗剪强度的影响。试验结果表明,在数值模拟试验条件下初始细粒含量变化对于细粒流失质量、峰值细粒流失率、土表位移及渗流前后的力学特性影响较试验中围压与水力梯度的影响更为显著。通过对微观组构的分析,发现不同细粒含量的试样在渗流过程中接触网络的构成与变动差异较大,细粒含量在35%的阈值附近,会发生土体力链传递结构的转换。三轴结果表明,细粒流失还会导致土体峰值强度降低、50%强度处的割线模量E50减小。

关键词: 流体力学-离散元耦合, 渗流侵蚀, 细粒含量, 水力梯度, 围压, 微观结构

Abstract: Seepage erosion can lead to the loss of particles in the soil with water flow, thereby changing the mechanical and hydraulic properties of the soil, and then causing the deformation and even damage of earth-rock dams in engineering. In this paper, the coupled CFD-DEM method is used to study the seepage erosion characteristics of gap-graded sandy soil, which is widely found in dam foundation, filter-base soil systems in earth-rock dams and gravel packing for sand control in oil and gas production, after reasonable simplification of its gradation. The effects of hydraulic gradient, confining pressure and fines content on seepage erosion in gap-graded sand soils were investigated through 8 groups of upward seepage simulation. Macroscopic phenomena such as the mass of fines loss, fines loss rate, soil surface settlement and microstructural changes were monitored in the tests and verified against previous indoor tests. The results showed that the effect of fines content on the mass of fines loss, peak fines loss rate and soil surface displacement from the numerical simulation was more significant than the effect of the confining pressure and hydraulic gradient in the tests. In addition, the analysis of microstructure demonstrated that the conversion of the soil force chain transfer structure occurred near the threshold of 25% fines content. The triaxial results indicated that the loss of fines also led to a decrease in peak strength and E50 modulu of soil.

Key words: coupled CFD-DEM, seepage erosion, fines content, hydraulic gradient, confining pressure, microstructure

中图分类号: TU 470
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