Abstract
Most failures or instabilities of geotechnical structures commonly result from shear failure in soil. In addition, many infrastructures are constructed within the unsaturated zone. Therefore, the determination of shear strength of unsaturated soil is crucial in geotechnical design. The soil-water characteristic curve (SWCC) is commonly used to estimate the shear strength of unsaturated soil because the direct measurement is time-consuming and costly. However, the uncertainty associated with the determined SWCC is rarely considered in the estimation of the shear strength. In this paper, the uncertainties of SWCC resulted from different factors are reviewed and discussed. The variability of the estimated shear strength for the unsaturated soil due to the uncertainty of SWCC associated with the best fit process is quantified by using the upper and lower bounds of the determined SWCC. On the other hand, the uncertainties of the estimated shear strength due to different initial void ratios or different confining pressures are quantified by adopting different SWCCs. As a result, it is recommended that the measured SWCC from the conventional Tempe cell or pressure plate needs to be corrected by considering different stress levels in the estimation of the shear strength of unsaturated soil.
概要
目的
系统讨论引起水-土特征曲线不确定性的各种可 能因素, 深入探讨水-土特征曲线的不确定性对非饱和土体抗剪强度的影响, 并总结采用水-土 特征曲线估算非饱和土体抗剪强度所需要考虑 的关键因素.
创新点
在采用水-土特征曲线计算非饱和土抗剪强度时, 综合考虑水-土特征曲线的不确定性.
方法
1. 查阅文献, 对比试验数据, 总结造成水-土特 征曲线不确定性的主要因素;2. 依据现有估算公 式, 采用不同水-土特征曲线估算非饱和土抗剪 强度;3. 对比估算结果和试验测量值, 讨论估算
过程需要注意的关键事项。结论
1. 同一土样在不同测试方法、不同试验环境及不同初始空隙比的情况下, 所获得的水-土特征曲 线可能表现各异;2. 在估算非饱和土抗剪强度 时, 必须考虑土体的应力状态(或者空隙比), 并对现有水-土特征曲线做必要修正, 以保证在估算过程中所采用的水-土特征曲线能够真实地反映剪切土样的孔径分布.
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Qian ZHAI wrote the first draft of the manuscript and edited the final version, Harianto RAHARDJO and Alfrendo SATYANAGA helped to organize the manuscript, and Guo-liang DAI and Yan-jun DU revised and edited the final version.
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Qian ZHAI, Harianto RAHARDJO, Alfrendo SATYANAGA, Guo-liang DAI, and Yan-jun DU declare that they have no conflict of interest.
Project supported by the National Natural Science Foundation of China (No. 51878160), the National Key Research and Development Program of China (No. 2017YFC00703408), and the Research Funding from China Huaneng Group Co. Ltd. (No. HNKJ19-H17)
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Zhai, Q., Rahardjo, H., Satyanaga, A. et al. Effect of the uncertainty in soil-water characteristic curve on the estimated shear strength of unsaturated soil. J. Zhejiang Univ. Sci. A 21, 317–330 (2020). https://doi.org/10.1631/jzus.A1900589
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DOI: https://doi.org/10.1631/jzus.A1900589
Key words
- Unsaturated shear strength
- Pore-size distribution function
- Variability
- Soil-water characteristic curve (SWCC)
- Confidence limits