颗粒形状对砂土力学特性的影响研究  

Study on the influence of particle shape on the mechanical properties of sand

作　　者：张宇 王晅[1,2] 张家生[1,2] 丁瑜 闫鹏 李度 ZHANG Yu;WANG Xuan;ZHANG Jiasheng;DING Yu;YAN Peng;LI Du(School of Civil Engineering,Central South University,Changsha 410075,China;National Engineering Research Center of High-speed Railway Construction Technology,Central South University,Changsha 410075,China;Shandong Highway Engineering Technology Research Center Co.,Ltd.,Jinan 250220,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学高速铁路建造技术国家工程研究中心,湖南长沙410075 [3]山东省公路工程技术研究中心有限公司,山东济南250220

出　　处：《铁道科学与工程学报》2022年第11期3256-3265,共10页Journal of Railway Science and Engineering

基　　金：中南大学2018级大学生创新创业训练计划支持项目(2021105330043)。

摘　　要：为了探讨砂土不同颗粒的形状特征对砂土力学特性的影响规律,建立考虑砂土颗粒形状影响的砂土强度计算公式模型。依据已有研究,选取3个描述砂土颗粒形状特征的参数(球度S,长宽比AR和凸度C),运用Image-pro plus软件对砂土和玻璃珠的形状轮廓进行二值化处理,得到标准砂和玻璃珠的颗粒形状量化结果,之后,通过引入整体颗粒形状参数O对从不同角度描述颗粒形状特征的3个参数进行整合表示,并配置5种具有不同整体颗粒形状参数的砂土试样进行不同围压条件下的常规三轴压缩试验。试验结果表明:颗粒形状特征的差异对砂土力学特性会产生较大的影响,具体表现在随着砂土整体颗粒形状参数O的增大,其内摩擦角不断减少;此外,随着整体颗粒形状参数O的减少,砂土的剪切软化程度逐渐降低,达到峰值强度后下降速率变慢;同时,基于砂土试样三轴压缩试验结果,并结合现有关于砂土峰值内摩擦角理论计算模型的研究成果,通过引入整体颗粒形状参数O,建立考虑整体颗粒形状参数O影响的砂土峰值内摩擦角计算公式。最后,配置2种不同整体颗粒形状参数的试验砂土,并在与之前砂土试样同样的试验条件下进行常规三轴压缩试验,并运用本文所建模型对试验结果进行预测,结果表明本文所建模型具有良好的适用性。In order to explore the influence of the shape characteristics of different sand particles on the mechanical properties of sand, a sand strength calculation formula was established considering the influence of particle shape. based on the previous research, three parameters(sphericality S, aspect ratio AR and convexity C)were selected to describe the shape characteristics of sand particles. The shape contours of sand and glass beads were binarized by Image-pro plus software. The quantitative results of particle shape of standard sand and glass beads were obtained. After that, by introducing the overall particle shape parameter, the three parameters describing the shape characteristics of particles from different angles were integrated and expressed. Five sand samples with different overall particle shape parameters were configured to carry out conventional triaxial compression tests under different confining pressures. The experimental results are drawn as follows. The difference of particle shape characteristics has a great influence on the mechanical properties of sand. With the increase of the overall particle shape parameter of sand, the internal friction angle decreases. At the same time,based on the triaxial compression test results of sand samples, combined with the existing theoretical calculation model of sand peak internal friction angle, by introducing the overall particle shape parameter, the calculation formula of sand peak internal friction angle considering the impact of the overall particle shape parameter was established. Finally, two kinds of sand with different overall particle shape parameters are configured, and the conventional triaxial compression test is carried out under the same test conditions as the previous sand sample.The test results are predicted by using the model established in this paper, and the results show that the model established in this paper has good applicability.

关 键 词：颗粒形状参数 砂土 力学特性 内摩擦角 

分 类 号：TU44[建筑科学—岩土工程]