Abstract
Artificial freezing is becoming a common method of enhancing soil quality when undertaking large scale underground structures in Shanghai. This paper presents the variation in the frozen strength of Shanghai muddy clay with temperature. SEM studies were undertaken to analyse the shape and size of the pores in the frozen material compared with the undisturbed clay. The results show that compared with undisturbed soil, the shape and the orientation of the pores in samples frozen at −10, −15 and −20°C did not significantly change after the compression testing, although the pore volume increased with decreasing temperature. The relationship between microstructure and moisture migration is discussed.
Résumé
La congélation des sols devient une technique usuelle pour améliorer la résistance des sols pour des travaux souterrains importants réalisés à Shanghai. L’article présente l’évolution, en fonction de la température, de la résistance de sols argileux gelés. Des études au microscope électronique à balayage ont été réalisées afin d’étudier la forme et la taille des pores d’échantillons congelés, par comparaison avec des échantillons intacts. Il apparaît que la forme et l’orientation des pores d’échantillons congelés à des températures de −10, −15 et −20°C ne changent pas de façon significative après les essais de compression, bien que le volume des pores augmente quand la température décroît. Les relations entre la microstructure et les phénomènes de migration des molécules d’eau sont discutées.
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Acknowledgments
This investigation was supported by the Chinese National Natural Science Fund, Project NO. 41072204, and Shanghai Leading Academic Discipline Project, Project No.B308, and Kwang-Hua Fund for College of Civil Engineering, Tongji University. The authors are deeply indebted to the three financial supporters.
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Tang, Yq., Zhou, J., Hong, J. et al. Quantitative analysis of the microstructure of Shanghai muddy clay before and after freezing. Bull Eng Geol Environ 71, 309–316 (2012). https://doi.org/10.1007/s10064-011-0380-9
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DOI: https://doi.org/10.1007/s10064-011-0380-9