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中南大学学报(自然科学版)

Journal of Central South University

第50卷    第11期    总第303期    2019年11月

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文章编号:1672-7207(2019)11-2859-11
多层土地基扩底抗拔桩离散元颗粒流研究
李飞1, 2, 3,杨俊杰1, 2,宋琦1, 2,孙涛4

(1. 中国海洋大学 海洋环境与生态教育部重点实验室,山东 青岛,266100;
2. 中国海洋大学 环境科学与工程学院,山东 青岛,266100;
3. 昌大建筑科技有限公司,山东 潍坊 ,261000;
4. 山东科技大学 地球科学与工程学院,山东 青岛,266590
)

摘 要: 以颗粒接触模量、颗粒刚度比、摩擦因数等为细观力学性质参数,建立多层砂土地基扩底抗拔桩计算模型,利用离散元颗粒流理论研究持力层厚度和持力层砂土密度对扩底桩抗拔承载特性的影响,并与模型试验结果进行对比。研究结果表明:力链传递方向主要沿扩大头斜上方32°左右方向发展;土层厚度及砂土密度不同,颗粒位移特征不同;数值模拟结果与模型试验结果吻合较好,当持力层厚度与扩大头直径之比(H/D)超过2.5时,极限承载力基本不再增加,是H/D=0.5时极限承载力的3.7~3.8倍;当持力层为密实砂时(相对密度为0.94),其极限抗拔承载力是中密砂(相对密度为0.55)的1.3~5.1倍。

 

关键词: 多层土地基;扩底桩;模型试验;颗粒流理论;承载特性

Study on discrete element particle flow of multi-layered ground-based expanded bottom uplift pile
LI Fei1, 2, 3, YANG Junjie1, 2, SONG Qi1, 2, SUN Tao4

1. Key Laboratory of Marine Environment and Ecology,
Ocean University of China, Ministry of Education, Qingdao 266100, China;
2. College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China;
3. Changda Building Technology Co. Ltd., Weifang 261000, China;
4. College of Earth Science and Engineering, Shandong University of Science and Technology,Qingdao 266590, China

Abstract:Taking the particle contact modulus, particle stiffness ratio, friction coefficient, etc. as parameters, the calculation model of multi-layer sand foundation excavation pile was established, and the influence of the thickness and sand density of the bearing layer on the uplift bearing capacity of the expanded pile was studied by discrete element particle flow theory. In addition, the results were compared with those of the model test. The results show that the direction of force chain transmission mainly develops along the direction of the enlarged head 32°, and the particle displacement characteristics are different with different soil thicknesses and sand densities. The numerical simulation agrees well with different model test results. When the ratio of the thickness of the bearing layer to the diameter of the enlarged head (H/D) exceeds 2.5, the ultimate bearing capacity does not increase any more, which is 3.7-3.8 times of that at H/D=0.5. Ultimate pullout capacity of the holding layer with dense sand (relative density 0.94) is 1.3-5.1 times of that of the layer with medium dense sand (relative density 0.55).

 

Key words: multi-layer foundation; bottom pile; model test; particle flow theory; bearing characteristics

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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