The stress–strain behaviour and critical state parameters of an unsaturated granular fill material under different suctions

Kai Liu, Jian Hua Yin, Wen Bo Chen, Wei Qiang Feng, Chao Zhou

Research output: Journal article publicationJournal articleAcademic researchpeer-review

5 Citations (Scopus)


In mountainous western China, a large number of granular materials are used as construction materials in high-fill embankments. These granular fill materials in the embankments are typically unsaturated owing to the arid and semi-arid climates in this area. However, previous studies on unsaturated soils primarily focus on fine-grained soils. In this study, a series of triaxial tests were performed to determine the critical state parameters of a granular fill material in q–p¯ , v–ln p¯ , and vw–ln p¯ planes. An upgraded double-cell triaxial system (DCTS) was used in net confining pressures ranging from 0 to 450 kPa and matric suctions ranging from 0 to 160 kPa. This study demonstrates the good performance of the upgraded DCTS in unsaturated soil testing. Experimental results show that the critical state lines are almost parallel to those of saturated soil in the q–p¯ plane, suggesting that the friction angle is independent of suction. The total cohesion and hence the shear strength increase with suction. In the v–ln p¯ plane, both the intercept and slope of the critical state line increase with suction. Finally, it is observed that the intercept and slope decrease with increasing suction in the vw–ln p¯ plane.

Original languageEnglish
Pages (from-to)3383-3398
Number of pages16
JournalActa Geotechnica
Issue number12
Publication statusPublished - Dec 2020


  • Critical state
  • High-fill embankment
  • Stress–strain
  • Suction
  • Unsaturated soil
  • Water retention curve

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Earth and Planetary Sciences (miscellaneous)

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