土工基础

土工基础 ›› 2023, Vol. 37 ›› Issue (6): 1003-1008.

• 测试技术 • 上一篇    下一篇

基于直剪试验的试样尺寸效应研究

苏 浩，程 芸，李育红，王菁菁，徐玲敏   

  1. （云南建投第一勘察设计有限公司,昆明 650030）
  • 收稿日期:2022-04-15 修回日期:2022-05-10 出版日期:2023-12-31 发布日期:2024-02-08
  • 作者简介:苏浩（1992-），男，助理工程师，研究方向为岩土工程勘察及土工试验。

Study on Sample Size Effect Based on Direct Undrained Shear Test

SU Hao, CHENG Yun, LI Yuhong, WANG Jingjing, XU Lingmin   

  1. (YICH First Engineering Survey and Design Co. Ltd., Kunming 650030)
  • Received:2022-04-15 Revised:2022-05-10 Online:2023-12-31 Published:2024-02-08

摘要： 土体作为一种特殊的散体材料，其各向异性及不均匀性尤为明显,且直接剪切试验中剪切破坏面的特定性等因素都导致了其不同于其他材料的破坏规律。分别采用直径61.8 mm和150 mm两种尺寸试样，进行了四种不同种类土的直接剪切试验，分析了土试样抗剪强度尺寸效应特性，研究表明：试样尺寸的变化不影响试样的应力应变变形特性；但试样尺寸的增大，抗剪强度峰值出现的位置更晚，抵抗变形的能力加强；随着试样尺寸增加，有效剪切面积比例增大，导致理论抗剪强度增大；对于黏性土，主要表现为黏聚力的增大，内摩擦角变化不大，而对于砂类土，主要表现为内摩擦角的增大。

关键词: 土试样, 直接快剪试验, 抗剪强度, 尺寸效应

Abstract: As a special granular material, the soil sample demonstrates obvious anisotropy and inhomogeneity. The characteristics of the shear failure surface in the direct shear test and other factors lead to its different failure modes from other materials. Direct shear tests of four types of soil samples were conducted by using samples with diameters of 61.8mm and 150mm, respectively. Based on the test results, the size effect of the soil shear strength is analyzed. The results show that the change of sample size does not affect the stress-strain deformation characteristics of the sample. However, with the increase of sample size, the peak shear strength appears later and the resistance to deformation is stronger. With the increase of sample size, the proportion of effective shear area increases, resulting in the increase of theoretical shear strength. For cohesive soil, the increase of cohesion is mainly manifested while the angle of internal friction doesn't change much. On the contrary, the increase of internal friction Angle is the main performance for sandy soil.

Key words: Soil Samples, Direct Undrained Shear Test, Shear Strength, Size Effect

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