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HONG Y , JIANG Y C, NI J N, et al.Micro-investigation of shear properties of mixed sand on discrete element method[J].Journal of Henan Polytechnic University(Natural Science) ,2024,43(1):172-179.

基于离散元方法的混合砂土剪切特性细观分析

洪勇, 姜奕辰, 倪嘉楠, 于超

青岛理工大学 土木工程学院，山东 青岛 266520

摘要:目的 为研究不同成分的砂土剪切破坏时的抗剪强度和体积变形差异。方法 采用室内试验与离散元模拟结合的方法，通过建立剪切带PFC2D模型，对剪切过程中单一质砂土和混合砂土细观参数的变化规律进行了研究。结果 发现粗砂、细砂、标准砂与混合砂土的剪切带形态、体积应变率等细观参数存在明显差异。结论 研究表明：砂土剪切应力大小受颗粒组成影响，表现为砂土剪切应力随粗颗粒含量的增加而增大，混合砂土剪切应力高于与其成分相同的单一质砂土；砂土中颗粒运动以上跨和下跨式为主，颗粒粒径越大运动位移越大，表现为体积应变率越大。砂土剪切时体积应变率受颗粒组成影响，表现为粗砂体积应变率高于标准砂和细砂；混合砂土体积应变率高于与其成分相同的单一质砂土。研究结果可为此类砂土地质结构破坏问题提供理论借鉴。

关键词:砂土;颗粒级配;抗剪强度;体积应变率;离散元;孔隙率

doi:10.16186/j.cnki.1673-9787.2022090063

基金项目:国家自然科学基金资助项目（41572259，41272341）

收稿日期:2022/09/24

修回日期:2023/01/10

出版日期:2024/01/25

Micro-investigation of shear properties of mixed sand on discrete element method

HONG Yong, JIANG Yichen, NI Jianan, YU Chao

School of Civil Engineering，Qingdao University of Technology，Qingdao 266520，Shandong，China

Abstract: Objective In order to study the difference of shear strength and volume deformation of sand with different components during shear failure. Methods The method of laboratory test and discrete element simulation is used to establish the PFC2D model of shear zone，and the variation law of meso-parameters of single sand and mixed sand during shear failure was studied. Results It is found that there are significant differences in shear zone morphology，volumetric strain rate and other mesoscopic parameters among coarse sand，fine sand，standard sand and mixed sand. Conclusion The results show that the shear stress of sand is affected by particle composition.The shear stress of sand increases with the increase of coarse particle content，and the shear stress of mixed sand is higher than that of single sand with the same composition.The movement of sand particles is mainly in the upper and lower spans.The larger particle size is，the greater the movement displacement is，and the higher the bulk strain rate is.The bulk strain rate of sand in shear is affected by particle composition.The bulk strain rate of coarse sand is higher than standard sand and fine sand.The bulk strain rate of mixed sand is higher than that of single sand with the same composition.The research results can provide theoretical reference for the failure of geological structure of sandy soil.

Key words:sandy soil;particle gradation;shear strength;volumetric strain rate;discrete element;porosity