Journal Published Online: 13 August 2024
Volume 47, Issue 6

FEM Analysis on Isotropic Consolidation of Unsaturated Soils Using Ceramic Disks and Microporous Membrane Filters for Suction Control

CODEN: GTJODJ

Abstract

Microporous membrane (MM) filters with a significantly thin thickness have recently been used as an alternative to ceramic disks for matric suction control in the axis-translation technique for element tests on unsaturated soils. Although researchers have highlighted some discrepancies in test results when ceramic disks and MM filters are used, the mechanism leading to these discrepancies has not yet been clarified. In this study, suction-controlled triaxial tests were first conducted on unsaturated completely decomposed granite using two filters. Then, it is natural to believe that the different thicknesses of ceramic disk and MM filters may significantly influence the suction equilibrium process of specimens. To clarify this issue, soil-water-air coupled finite element modeling was performed to simulate the consolidation process in triaxial tests as an initial/boundary value problem. In the numerical calculation, the influence of the void ratio on the water retention curve (WRC) of soil was properly considered by adopting a deformation-dependent WRC model. In particular, the ceramic disk and MM filter, along with the specimens, were modeled, and their differences in thickness were considered. The calculated results show that a nonuniform distribution of suction occurred in the ceramic disk, leading to greater drainage discharge of the specimens. In other words, the influence of the thickness difference between the MM filter and ceramic disk cannot be neglected. However, regardless of whether ceramic discs or MM filters are used, the uneven distribution of the state variables in the specimens may occur in the triaxial tests for unsaturated soils, which emphasizes the importance of assessing the soil tests using the present axis-translation technique as initial/boundary value problems.

Author Information

Xiong, Xi
Faculty of Geoscience and Civil Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa, Japan
Kobayashi, Shun-ichi
Faculty of Geoscience and Civil Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa, Japan
Izumi, Hiroyuki
Department of Civil Engineering, Nagoya Institute of Technology, Nagoya, Aichi, Japan
Zhang, Feng
Department of Civil Engineering, Nagoya Institute of Technology, Nagoya, Aichi, Japan Department of Civil Engineering, Tongji University, Shanghai, China
Pages: 23
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Stock #: GTJ20230439
ISSN: 0149-6115
DOI: 10.1520/GTJ20230439