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An extended numerical manifold method for unsaturated soil‐water interaction analysis at micro‐scale
Author(s) -
Sun Hao,
Wu Zhijun,
Zheng Liange,
Yang Yongtao,
Huang Da
Publication year - 2021
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/nag.3211
Subject(s) - capillary action , water retention curve , soil water , geotechnical engineering , mechanics , soil mechanics , water content , scale (ratio) , porosity , materials science , mathematics , soil science , hydraulic conductivity , geology , physics , composite material , quantum mechanics
To investigate unsaturated soil‐water interaction at micro‐scale, this study extends the numerical manifold method (NMM) by incorporating a soil‐water coupling model considering specific capillary water distribution and capillary force calculation. The soil skeleton is constructed by a soil skeleton generation algorithm with random polygons. To more realistically capture the interaction between soil grains and capillary water, a capillary mechanics‐based geometric algorithm is proposed to iteratively calculate the capillary water distribution. The capillary forces corresponding to the capillary water distribution are calculated based on the Young‐Laplace equation. The proposed capillary water solving framework is first verified by reproducing the soil‐water characteristic curve and the capillary water distribution of an ideal contact‐disk model against analytical solutions. To further validate the ability of the capillary water solving framework to predict hydraulic behavior of the real soil, a laboratory test on the Toyoura sand is reproduced numerically. Then an ideal direct shear test is performed to further validate the two‐way soil‐water coupling procedure, in which a comparison between the numerical and analytical results regarding the shear strength and matric suction is presented. Finally, microscopic hydraulic and compression tests are conducted on two soil specimens with the same porosity and mean grain diameter but different uniformity coefficients. The results elucidate that the extended method is a potential tool to explore unsaturated soil behaviors at micro‐scale.