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Geomechanics and Engineering Volume 31, Number 5, December10 2022 , pages 519-527 DOI: https://doi.org/10.12989/gae.2022.31.5.519 |
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Effect of water distribution on shear strength of compacted loess |
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Kang-ze Yuan, Wan-kui Ni, Xiang-fei Lü and Hai-man Wang
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| Abstract | ||
| Shear failure in soil is the primary cause of most geotechnical structure failures or instability. Soil water content is a significant factor affecting soil shear strength. In this study, the shear strength of samples with different water contents was tested. The shear strength, cohesion, and internal friction angle decreased with increasing water content. Based on the variation of cohesion and internal friction angle, the water content zone was divided into a high-water content zone and low-water content zone with a threshold water content of 15.05%. Cohesion and internal friction angle have a good linear relationship with water content in both zones. Environmental Scanning Electron Microscopy (ESEM) test presented that the aggregates size of the compacted loess gradually increases with increasing water content. Meanwhile, the clay in the compacted loess forms a matric that envelops around the surface of the aggregates and fills the inter-aggregates pores. A quantitative analysis of bound water and free water under different water contents using a nuclear magnetic resonance (NMR) test was carried out. The threshold water content between bound water and free water was slightly below the plastic limit, which is consistent with the results of shear strength parameters. Combined with the T2 distributions obtained by NMR, one can define a T2 relaxation time of 1.58 ms as the boundary point for bound water distribution without free water. Finally, the effects of bound water and free water on shear strength parameters were analyzed using linear regression analysis. | ||
| Key Words | ||
| bound water; ESEM; linear regression analysis; loess; shear strength | ||
| Address | ||
| Kang-ze Yuan: Department of Geological Engineering, College of Geological Engineering and Surveying and Mapping, Chang'An University, No.126 Yanta Road, Xi'an, Shaanxi 710054, P.R. China; Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milano, Italy Wan-kui Ni, Xiang-fei Lü and Hai-man Wang: Department of Geological Engineering, College of Geological Engineering and Surveying and Mapping, Chang'An University, No.126 Yanta Road, Xi'an, Shaanxi 710054, P.R. China | ||