Geomechanics and Engineering

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Thaw consolidation behavior of frozen soft clay with calcium chloride

  • Wang, Songhe (Institute of Geotechnical Engineering, Xi'an University of Technology) ;
  • Wang, Qinze (Institute of Geotechnical Engineering, Xi'an University of Technology) ;
  • Xu, Jian (School of Civil Engineering, Xi'an University of Architecture and Technology) ;
  • Ding, Jiulong (Institute of Geotechnical Engineering, Xi'an University of Technology) ;
  • Qi, Jilin (College of Civil and Transportation Engineering, Beijing University of Civil Engineering and Architecture) ;
  • Yang, Yugui (State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology) ;
  • Liu, Fengyin (Institute of Geotechnical Engineering, Xi'an University of Technology)
  • Received : 2019.01.09
  • Accepted : 2019.05.28
  • Published : 2019.06.10
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Abstract

Brine leakage is a common phenomenon during construction facilitated by artificial freezing technique, threatening the stability of frozen wall due to the continual thawing of already frozen domain. This paper takes the frequently encountered soft clay in Wujiang District as the study object, and remolded specimens were prepared by mixing calcium chloride solutions at five levels of concentration. Both the deformation and pore water pressure of frozen specimens during thawing were investigated by two-stage loading tests. Three sections were noted from the changes in the strain rate of specimens during thawing at the first-stage load, i.e., instantaneous, attenuated, and quasi-stable sections. During the second-stage loading, the deformation of post-thawed soils is closely correlated with the dissipation of pore water pressure. Two characteristic indexes were obtained including thaw-settlement coefficient and critical water content. The critical water content increases positively with salt content. The higher water content of soil leads to a larger thaw-settlement coefficient, especially at higher salt contents, based on which an empirical equation was proposed and verified. The normalized pore water pressure during thawing was found to dissipate slower at higher salt contents, with a longer duration to stabilize. Three physical indexes were experimentally determined such as freezing point, heat conductivity and water permeability. The freezing point decreases at higher salt contents, especially as more water is involved, like the changes in heat conductivity. The water permeability maintains within the same order at the considered range of salt contents, like the development of the coefficient of consolidation. The variation of the pore volume distribution also accounts for this.

Keywords

Acknowledgement

Supported by : National Natural Science Foundation of China, Beijing Municipal Institutions

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