Effects of Structure on the Compression Behavior of Unsaturated Loess
Publication: International Journal of Geomechanics
Volume 21, Issue 4
Abstract
The influence of structure plays a strong part in hydromechanical properties of soil. A series of suction-controlled oedometer tests have been conducted to explore the compression behavior of intact and compacted loess. The main findings show the following: (1) the yield stress of intact loess is higher than that of compacted loess at a given initial void ratio and under constant suction; (2) the slope of the normal compression line [λ(s)] of compacted loess is larger than that of intact loess; (3) the λ(s) value of intact loess initially increases sharply as suction increases and then trends to a slow decrease as suction increases further, while λ(s) of compacted loess continues to increase; (4) the λ(s) value of compacted loess can be fitted precisely with the Barcelona basic model; and (5) intact loess exhibits anisotropic behavior, in which a vertically trimmed specimen has a higher yield stress and λ(s) value than a horizontally trimmed specimen. The results showed that intact specimens and compacted specimens have different hydromechanical properties. Moreover, anisotropic behavior has also been found in unsaturated silty loess.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors acknowledge the financial support provided by the National Nature Science Foundation of China (Grant Nos. 41790441 and 41772316) and the National Key R&D Program of China (Grant No. 2018YFC1504700). The authors also thank Dr. Kai Liu for insightful comments on the draft manuscript.
Notation
The following symbols are used in this paper:
- e
- void ratio;
- N(s)
- intercept of the normal compression line;
- Sr
- degree of saturation;
- s
- matrix suction (ua − uw);
- ua
- pore-air pressure;
- uw
- pore-water pressure;
- θ
- specific water volume;
- λ(s)
- slope of the normal compression line; and
- net vertical stress .
References
Alonso, E. E., A. Gens, and A. Josa. 1990. “A constitutive model for partially saturated soils.” Géotechnique 40 (3): 405–430. https://doi.org/10.1680/geot.1990.40.3.405.
Barden, L. 1965. “Consolidation of compacted and unsaturated clays.” Géotechnique 15 (3): 267–286. https://doi.org/10.1680/geot.1965.15.3.267.
Burland, J. B. 1990. “On the compressibility and shear strength of natural clays.” Géotechnique 40 (3): 329–378. https://doi.org/10.1680/geot.1990.40.3.329.
Cui, Y. J., and P. Delage. 1996. “Yielding and plastic behaviour of an unsaturated compacted silt.” Géotechnique 46 (2): 291–311. https://doi.org/10.1680/geot.1996.46.2.291.
Estabragh, A. R., and A. A. Javadi. 2015. “Effect of soil density and suction on the elastic and plastic parameters of unsaturated silty soil.” Int. J. Geomech. 15 (5): 04014079. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000422.
Estabragh, A. R., A. A. Javadi, and J. C. Boot. 2004. “Effect of compaction pressure on consolidation behaviour of unsaturated silty soil.” Can. Geotech. J. 41 (3): 540–550. https://doi.org/10.1139/t04-007.
Estabragh, A. R., M. Moghadas, M. Moradi, and A. A. Javadi. 2017. “Consolidation behavior of an unsaturated silty soil during drying and wetting.” Soils Found. 57 (2): 277–287. https://doi.org/10.1016/j.sandf.2017.03.005.
Gibbs, H. J., and Holland, W. Y. 1960. Petrographic and engineering properties of loess. Denver: Bureau of Reclamation, US Dept. of the Interior.
Haeri, S. M., A. A. Garakani, H. R. Roohparvar, C. S. Desai, S. M. H. S. Ghafouri, and K. S. Kouchesfahani. 2019. “Testing and constitutive modeling of lime-stabilized collapsible loess. I: Experimental investigations.” Int. J. Geomech. 19 (4): 04019006. https://doi.org/10.1061/(ASCE)GM.1943-5622.0001364.
Haeri, S. M., A. Khosravi, A. A. Garakani, and S. Ghazizadeh. 2017. “Effect of soil structure and disturbance on hydromechanical behavior of collapsible loessial soils.” Int. J. Geomech. 17 (1): 04016021. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000656.
Hattab, M., and J. M. Fleureau. 2011. “Experimental analysis of kaolinite particle orientation during triaxial path.” Int. J. Num. Anal. Methods Geomech. 35 (8): 947–968. https://doi.org/10.1002/nag.936.
Hicher, P. Y., H. Wahyudi, and D. Tessier. 2000. “Microstructural analysis of inherent and induced anisotropy in clay.” Mech. Cohesive-frict. Mater. 5 (5): 341–371. https://doi.org/10.1002/1099-1484(200007)5:5%3C341::AID-CFM99%3E3.0.CO;2-C.
Hilf, J. W. 1956. An investigation of pore pressure in compacted cohesive soils. Technical Memorandum 654. Denver: United States Bureau of Reclamation, Design and Contruction Division.
Juang, C. H., T. Dijkstra, J. Wasowski, and X. Meng. 2019. “Loess geohazards research in China: Advances and challenges for mega engineering projects.” Eng. Geol. 251: 1–10. https://doi.org/10.1016/j.enggeo.2019.01.019.
Kayadelen, C. 2008. “The consolidation characteristics of an unsaturated compacted soil.” Environ. Geol. 54 (2): 325–334. https://doi.org/10.1007/s00254-007-0819-2.
Kruse, G. A. M., T. A. Dijkstra, and F. Schokking. 2007. “Effects of soil structure on soil behaviour: Illustrated with loess, glacially loaded clay and simulated flaser bedding examples.” Eng. Geol. 91 (1): 34–45. https://doi.org/10.1016/j.enggeo.2006.12.011.
Li, P., H. Qian, and J. Wu. 2014. “Environment: Accelerate research on land creation.” Nature 510 (7503): 29–31. https://doi.org/10.1038/510029a.
Liu, D. S. 1985. Loess and the environment. [In Chinese.] Beijing, China: China Ocean Press.
Lloret, A., M. V. Villar, M. Sànchez, A. Gens, X. Pintado, and E. E. Alonso. 2003. “Mechanical behaviour of heavily compacted bentonite under high suction changes.” Géotechnique 53 (1): 27–40. https://doi.org/10.1680/geot.2003.53.1.27.
Matsuoka, H., D. Sun, A. Kogane, N. Fukuzawa, and W. Ichihara. 2002. “Stress–strain behaviour of unsaturated soil in true triaxial tests.” Can. Geotech. J. 39 (3): 608–619. https://doi.org/10.1139/t02-031.
Munõz-Castelblanco, J., P. Delage, J. M. Pereira, and Y. J. Cui. 2011. “Some aspects of the compression and collapse behaviour of an unsaturated natural loess.” Géotech. Lett. 1 (2): 17–22. https://doi.org/10.1680/geolett.11.00003.
Ng, C. W. W., Q. Cheng, and C. Zhou. 2018. “Thermal effects on yielding and wetting-induced collapse of recompacted and intact loess.” Can. Geotech. J. 55 (8): 1095–1103. https://doi.org/10.1139/cgj-2017-0332.
Ng, C. W. W., Q. Y. Mu, and C. Zhou. 2017. “Effects of soil structure on the shear behaviour of an unsaturated loess at different suctions and temperatures.” Can. Geotech. J. 54 (2): 270–279. https://doi.org/10.1139/cgj-2016-0272.
Ng, C. W. W., H. Sadeghi, S. K. B. Hossen, C. F. Chiu, E. E. Alonso, and S. Baghbanrezvan. 2016. “Water retention and volumetric characteristics of intact and re-compacted loess.” Can. Geotech. J. 53 (8): 1258–1269. https://doi.org/10.1139/cgj-2015-0364.
Sivakumar, V. 1993. “A critical state framework for unsaturated soils.” Ph.D. thesis, Dept. of Civil and Structural Engineering, Univ. of Sheffield.
Sivakumar, V., W. C. Tan, E. J. Murray, and J. D. McKinley. 2006. “Wetting, drying and compression characteristics of compacted clay.” Géotechnique 56 (1): 57–62. https://doi.org/10.1680/geot.2006.56.1.57.
Sun, D. A, W. San, W. Yan, and J. Li. 2010. “Hydro-mechanical behaviours of highly compacted sand-bentonite mixture.” J. Rock Mech. Geotech. Eng. 2 (1): 79–85. https://doi.org/10.3724/SP.J.1235.2010.00079.
Thu, T. M., H. Rahardjo, and E.-C. Leong. 2007. “Soil–water characteristic curve and consolidation behavior for a compacted silt.” Can. Geotech. J. 44 (3): 266–275. https://doi.org/10.1139/t06-114.
Vanapalli, S. K., D. G. Fredlund, and D. E. Pufahl. 1999. “The influence of soil structure and stress history on the soil-water characteristics of a compacted till.” Géotechnique 49 (2): 143–159. https://doi.org/10.1680/geot.1999.49.2.143.
van Genuchten, M. T. 1980. “A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.” Soil Sci. Soc. Am. J. 44 (5): 892–898. https://doi.org/10.2136/sssaj1980.03615995004400050002x.
Vilar, O. M., and R. A. Rodrigues. 2011. “Collapse behavior of soil in a Brazilian region affected by a rising water table.” Can. Geotech. J. 48 (2): 226–233. https://doi.org/10.1139/T10-065.
Villar, M. V. 1999. “Investigation of the behaviour of bentonite by means of suction-controlled oedometer tests.” Eng. Geol. 54 (1–2): 67–73. https://doi.org/10.1016/S0013-7952(99)00062-9.
Wen, B.-P., and Y.-J. Yan. 2014. “Influence of structure on shear characteristics of the unsaturated loess in Lanzhou, China.” Eng. Geol. 168: 46–58. https://doi.org/10.1016/j.enggeo.2013.10.023.
Wheeler, S. J., D. Gallipoli, and M. Karstunen. 2002. “Comments on use of the Barcelona Basic Model for unsaturated soils.” Int. J. Numer. Anal. Methods Geomech. 26 (15): 1561–1571. https://doi.org/10.1002/nag.259.
Wheeler, S. J., and V. Sivakumar. 1995. “An elasto-plastic critical state framework for unsaturated soil.” Géotechnique 45 (1): 35–53. https://doi.org/10.1680/geot.1995.45.1.35.
Wheeler, S. J., and V. Sivakumar. 2000. “Influence of compaction procedure on the mechanical behaviour of an unsaturated compacted clay. Part 2: Shearing and constitutive modelling.” Géotechnique 50 (4): 369–376. https://doi.org/10.1680/geot.2000.50.4.369.
Wu, L. Z., and A. P. S. Selvadurai. 2016. “Rainfall infiltration-induced groundwater table rise in an unsaturated porous medium.” Environ. Earth Sci. 75 (2): 1–11.
Xu, L., and M. R. Coop. 2016. “Influence of structure on the behavior of a saturated clayey loess.” Can. Geotech. J. 53 (6): 1026–1037. https://doi.org/10.1139/cgj-2015-0200.
Xu, L., and M. R. Coop. 2017. “The mechanics of a saturated silty loess with a transitional mode.” Géotechnique 67 (7): 581–596. https://doi.org/10.1680/jgeot.16.P.128.
Xu, L., C. Gao, T. Lan, J. Lei, and L. Zuo. 2020. “FFT-based homogenisation of the effective mechanical response of gas hydrate bearing sediments.” Géotech. Lett. 10 (2): 1–26. https://doi.org/10.1680/jgele.19.00051.
Xu, L., C. Gao, and X. Wei. 2019. “Anisotropic behaviour of a saturated clayey loess.” Géotech. Lett. 9 (1): 28–34. https://doi.org/10.1680/jgele.18.00125.
Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 21 • Issue 4 • April 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Apr 7, 2020
Accepted: Nov 8, 2020
Published online: Feb 9, 2021
Published in print: Apr 1, 2021
Discussion open until: Jul 9, 2021
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.