Hydraulic conductivity and X-ray diffraction tests of unsaturated bentonites with a multi-ring and their predictions by pores distributions

Kunlin Ruan*, Hideo Komine, Daichi Ito, Kentaro Miyoshi, Takahiro Gotoh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Following instantaneous profiling method, a new multi-ring was applied in wetting apparatus to ascertain water diffusivities of three bentonites (MX-80, Kunigel-V1, and Kunibon). Hydraulic conductivities of unsaturated bentonites were calculated combining water diffusivities and soil water retention curves (SWRC). Basal spacings were achieved by sending slices from the multi-ring to X-ray diffraction (XRD) tests. A dual pores system was proposed: 1) micro pore (inter-layer pores); and 2) macro pore (inter-particle pores and inter-aggregate pores). By discussing water flow mechanisms in bentonite, it was supposed that: moveable waters flow through macro pore. Porosity and tortuosity of saturated macro pore were used instead of porosity and tortuosity of saturated total pore in traditional Kozeny-Carmen (KC) equation, which was designated as modified KC eq. A new relative permeability was raised for predicting unsaturated bentonites hydraulic conductivities. Macroporosity and macrovolumetric water content were obtained from estimated basal spacing during saturation. Comprehensive comparisons between experimental database and predictions were conducted. Results revealed that the modified KC equation can predict both saturated and unsaturated hydraulic conductivities better.

Original languageEnglish
Article number106738
JournalEngineering Geology
Volume306
DOIs
Publication statusPublished - 2022 Sep 5

Keywords

  • Bentonites
  • Hydraulic conductivities
  • Kozeny-Carmen eq.
  • X-Ray diffraction

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geology

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