季节冻土地区粗颗粒土-土工格栅界面特性离散元细观研究

刘庆光; 刘杰; 雷兵兵; 张江鹏; 白奇玉

doi:10.13928/j.cnki.wrahe.2025.S1.098

水利水电技术（中英文） ›› 2025, Vol. 56 ›› Issue (S1) : 647 -656. DOI: 10.13928/j.cnki.wrahe.2025.S1.098

工程地质

季节冻土地区粗颗粒土-土工格栅界面特性离散元细观研究

刘庆光 ¹ ,
刘杰 ¹^,²^,³^,⁴ ,
雷兵兵 ²^,³ ,
张江鹏 ²^,⁴ ,
白奇玉 ¹^,²^,⁴

作者信息 +

Discrete element mesoscopic study on interface characteristics of coarse-grained soil-geogrid in seasonal frozen soil area

Qingguang LIU ¹ ,
Jie LIU ¹^,²^,³^,⁴ ,
Bingbing LEI ²^,³ ,
Jiangpeng ZHANG ²^,⁴ ,
Qiyu BAI ¹^,²^,⁴

Author information +

文章历史 +

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摘要

为研究在季节冻土区，显著的温度波动改变筋土界面力学特性进而影响寒区加筋土工程的力学稳定性和长期耐久性能。通过离散元法PFC^3D软件，针对-5℃下粗粒土-土工格栅室内直剪试验，进行直剪试验数值模拟。方法研究了土工格栅加筋粗粒土在直剪试验中土工格栅的单体变形受力、孔隙率变化、粗粒土的位移与旋转及土体内部的力链应力场等宏细观特性演化过程，并通过模拟与室内试验结果的对比分析，验证模型的准确性和实用性。结果表明：在-5℃的低温条件下，随着剪切位移的增加，变形逐渐明显，且纵肋的变形显著大于横肋。深入分析土体内部不同截面的孔隙率变化，可以观察到孔隙率随着剪切位移的增长而降低，且剪切面上下的孔隙率呈现非对称分布模式。剪切位移主要集中于剪切面周围，位移呈现左高右低的特征，并随着剪切的进行，土体内部形成中心对称的拱形结构。进一步探究土体的应力场变化，初始时强力链沿盒壁分布，形成低应力区，而应力峰值过后，颗粒间接触力减少，力链沿对角线分布，这种分布特征与施加的水平推力有着密切的关联。研究成果从细观角度对粗粒土的加筋机理提供了理论解释，可为季节性冻土区的加筋土工程设计参数提供了数据支撑。

Abstract

In order to seasonally frozen regions, significant temperature fluctuations affect the mechanical stability and long-term durability of reinforced soil engineering in cold areas by changing the mechanical properties of the reinforced soil interface. This study uses the discrete element method PFC^3D software. A numerical simulation of the direct shear test was carried out for coarse-grained soil-geogrid indoor direct shear test at-5 ℃. The evolution process of macro and micro characteristics of geogrid reinforced coarse-grained soil in direct shear tests, such as single deformation force, porosity change, displacement and rotation of coarse-grained soil, and force chain stress field inside the soil, is revealed. The accuracy and practicability of the model are verified by comparing the simulation result with the laboratory test result. The results show that under the condition of-5 ℃ low temperature, with the increase of shear displacement, the deformation is gradually obvious, and the deformation of the longitudinal rib is significantly greater than that of the transverse rib. An in-depth analysis of the porosity changes of different sections inside the soil shows that the porosity decreases with the increase of shear displacement, and the porosity on the shear surface and below shows an asymmetric distribution pattern. The shear displacement is mainly concentrated around the shear surface, and the displacement is characterized by high left and low right. As the shear proceeds, a centrally symmetrical arch structure is formed inside the soil. The stress field of the soil is further explored. The strong chain is initially distributed along the wall to create a low-stress zone. After the stress peak, the contact force between the particles decreases, and the force chain is distributed along the diagonal. This distribution feature is closely related to the applied horizontal thrust. The research findings provides a theoretical explanation for the reinforcement mechanism of coarse-grained soil from the microscopic point of view and provides data support for the design parameters of reinforced soil engineering in seasonal frozen soil areas.