Fabric anisotropy; Micro-scale; Triaxial test; Unsaturated soil; Water distribution; X-ray CT; Geotechnical Engineering and Engineering Geology; Earth and Planetary Sciences (miscellaneous)
Abstract :
[en] The mechanical behaviours of unsaturated soils are highly related to the water content and pore water and air distributions. Under the context of climate change, geo-disasters related to soil moisture change attract more and more research attentions. Due to the heterogeneity of soil textures and the complicated morphology of liquid phases, it is crucial to understand the microstructural features of unsaturated soils. This work presents a study based on a miniaturized suction controlled triaxial device which is suitable for micro-CT image analysis. A fine sand is sheared in this device under different suction levels while CT scans are taken at different strain stages. After image 3D reconstruction, image trinarization, label analysis, contact detection and other customized image analysis and calculations, the micro-mechanisms of unsaturated granular soils upon triaxial shearing are investigated. It is observed that the inter-particle contact coordination number is reduced after shearing due to the dilation behaviour and the sample with the highest capillary strength has the highest coordination number. Although there is an initial fabric anisotropy due to gravity and sample compaction, triaxial loading will further enlarge the fabric anisotropy of the solid phase and the solid fabric anisotropy is also associated with shear strength. With the development of shear band, water drains out and the quantity of small-volume liquid clusters in the liquid bridge increases. This shifts the distributions of inter-facial areas. The effective stress tensor is interpreted microscopically based on small RVEs. Based on the CT image analysis, the suction-induced stress component is not an isotropic term and the anisotropy of the water phase is increased with triaxial deformation as well as decrease in degree of saturation when there are more isolated water bridges formed around solid contacts.
Disciplines :
Civil engineering
Author, co-author :
Wang, Ji-Peng ; School of Civil Engineering, Shandong University, Jinan, China
Luan, Ji-Yuan; School of Civil Engineering, Shandong University, Jinan, China
Gao, Xu-Guang; School of Civil Engineering, Shandong University, Jinan, China
Liu, Tai-Heng; School of Civil Engineering, Shandong University, Jinan, China
Andò, Edward; Laboratoire 3SR, Université Grenoble Alpes, Grenoble, France ; EPFL Center for Imaging, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
François, Bertrand ; Université de Liège - ULiège > Urban and Environmental Engineering ; Building Architecture and Town Planning Department (BATir), Université Libre de Bruxelles, Brussels, Belgium
Language :
English
Title :
A micro-investigation of unsaturated sand in mini-triaxial compression based on micro-CT image analysis
Publication date :
November 2022
Journal title :
Acta Geotechnica
ISSN :
1861-1125
eISSN :
1861-1133
Publisher :
Springer Science and Business Media Deutschland GmbH
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE] NSCF - National Natural Science Foundation of China [CN]
Funding text :
This work was funded by F.R.S-FNRS of Belgium (PDR.T.1002.14) and NFSC of China (Nos: 51909139, 52011530458). The first author also acknowledges the support of Taishan Scholar Project of Shandong Province of China.
Alonso EE, Pereira J-M, Vaunat J, Olivella S (2010) A microstructurally based effective stress for unsaturated soils. Géotechnique 60:913–925. 10.1680/geot.8.P.002
Andò E, Hall SA, Viggiani G, Desrues J, Bésuelle P (2012) Grain-scale experimental investigation of localised deformation in sand: a discrete particle tracking approach. Acta Geotech 7:1–13. 10.1007/s11440-011-0151-6
Andò E, Hall SA, Viggiani G, Desrues J, Bésuelle P (2012) Experimental micromechanics: grain-scale observation of sand deformation. Géotech Lett 2:107–112. 10.1680/geolett.12.00027
Bruchon J-F, Pereira J-M, Vandamme M, Lenoir N, Delage P, Bornert M (2013) Full 3D investigation and characterisation of capillary collapse of a loose unsaturated sand using X-ray CT. Granul Matter 15:783–800. 10.1007/s10035-013-0452-6
Cheng Z, Zhou B, Wang J (2020) Tracking particles in sands based on particle shape parameters. Adv Powder Technol 31:2005–2019. 10.1016/j.apt.2020.02.033
Cnudde V, Boone MN (2013) High-resolution X-ray computed tomography in geosciences: a review of the current technology and applications. Earth-Sci Rev 123:1–17. 10.1016/j.earscirev.2013.04.003
Cnudde V, Cwirzen A, Masschaele B, Jacobs PJS (2009) Porosity and microstructure characterization of building stones and concretes. Eng Geol 103:76–83. 10.1016/J.ENGGEO.2008.06.014
Cormack AM (1973) Reconstruction of densities from their projections, with applications in radiological physics. Phys Med Biol 18:195–207. 10.1088/0031-9155/18/2/003
Dalla E, Hilpert M, Miller CT (2002) Computation of the interfacial area for two-fluid porous medium systems. J Contam Hydrol 56:25–48. 10.1016/S0169-7722(01)00202-9
Desrues J, Chambon R, Mokni M, Mazerolle F (1996) Void ratio evolution inside shear bands in triaxial sand specimens studied by computed tomography. Géotechnique 46:529–546. 10.1680/geot.1996.46.3.529
Duriez J, Wan R (2017) Contact angle mechanical influence in wet granular soils. Acta Geotech 12:67–83. 10.1007/s11440-016-0500-6
Duriez J, Wan R, Pouragha M, Darve F (2018) Revisiting the existence of an effective stress for wet granular soils with micromechanics. Int J Numer Anal Methods Geomech 42:959–978. 10.1002/nag.2774
Hall SA, Bornert M, Desrues J, Pannier Y, Lenoir N, Viggiani G, Bésuelle P (2010) Discrete and continuum analysis of localised deformation in sand using X-ray μCT and volumetric digital image correlation. Géotechnique 60:315–322. 10.1680/geot.2010.60.5.315
Higo Y, Oka F, Kimoto S, Sanagawa T, Matsushima Y (2011) Study of strain localization and microstructural changes in partially saturated sand during triaxial tests using microfocus X-ray CT. Soils Found 51:95–111. 10.3208/sandf.51.95
Higo Y, Oka F, Sato T, Matsushima Y, Kimoto S (2013) Investigation of localized deformation in partially saturated sand under triaxial compression using microfocus X-ray CT with digital image correlation. Soils Found 53:181–198. 10.1016/j.sandf.2013.02.001
Hou X, Vanapalli SK, Li T (2019) Wetting-induced collapse behavior associated with infiltration: a case study. Eng Geol 258:105146. 10.1016/J.ENGGEO.2019.105146
Hounsfield GN (1973) Computerized transverse axial scanning (tomography): part 1 description of system. Br J Radiol 46:1016–1022. 10.1259/0007-1285-46-552-1016
Wang JP, Lambert P, Kock T, Cnudde V, François B (2019) Investigation of the effect of specific interfacial area on strength of unsaturated granular materials by X-ray tomography. Acta Geotech 14:1545–1559. 10.1007/s11440-019-00765-2
Kanatani K-I (1984) Distribution of directional data and fabric tensors. Int J Eng Sci 22:149–164
Ketcham RA, Carlson WD (2001) Acquisition, optimization and interpretation of X-ray computed tomographic imagery: applications to the geosciences. Comput Geosci 27:381–400. 10.1016/S0098-3004(00)00116-3
Khaddour G, Riedel I, Andò E, Charrier P, Bésuelle P, Desrues J, Viggiani G, Salager S (2018) Grain-scale characterization of water retention behaviour of sand using X-ray CT. Acta Geotech 13:497–512. 10.1007/s11440-018-0628-7
Kido R, Higo Y (2020) Microscopic characteristics of partially saturated dense sand and their link to macroscopic responses under triaxial compression conditions. Acta Geotech 15:3055–3073. 10.1007/s11440-020-01049-w
Kido R, Higo Y, Takamura F, Morishita R, Khaddour G, Salager S (2020) Morphological transitions for pore water and pore air during drying and wetting processes in partially saturated sand. Acta Geotech 15:1745–1761. 10.1007/s11440-020-00939-3
Koliji A, Vulliet L, Laloui L (2010) Structural characterization of unsaturated aggregated soil. Can Geotech J 47:297–311. 10.1139/T09-089
Laloui L, Nuth M (2009) On the use of the generalised effective stress in the constitutive modelling of unsaturated soils. Comput Geotech 36:20–23. 10.1016/j.compgeo.2008.03.002
Lu N, Godt JW, Wu DT (2010) A closed-form equation for effective stress in unsaturated soil. Water Resour Res 46:W05515. 10.1029/2009WR008646
Manahiloh K, Muhunthan B (2012) Characterizing liquid phase fabric of unsaturated specimens from X-ray computed tomography images. In: Mancuso C, Jommi C, D’Onza F (eds) Unsaturated soils: research and applications. Springer, Berlin Heidelberg, pp 71–80
Milatz M, Hüsener N, Andò E, Viggiani G, Grabe J (2021) Quantitative 3D imaging of partially saturated granular materials under uniaxial compression. Acta Geotech 2021:1–28. 10.1007/S11440-021-01315-5
Moscariello M, Cuomo S, Salager S (2017) Capillary collapse of loose pyroclastic unsaturated sands characterized at grain scale. Acta Geotech. 10.1007/s11440-017-0603-8
Pan C, Hilpert M, Miller CT (2004) Lattice-Boltzmann simulation of two-phase flow in porous media. Water Resour Res. 10.1029/2003WR002120
Richefeu V, Radjai F, Delenne J-Y (2016) Lattice Boltzmann modelling of liquid distribution in unsaturated granular media. Comput Geotech 80:353–359. 10.1016/j.compgeo.2016.02.017
Riedel I, Andò E, Salager S, Bésuelle P, Viggiani G (2012) Water retention behaviour explored by X-ray CT analysis. Unsaturated soils: research and applications. Springer Berlin Heidelberg, Berlin, Heidelberg, pp 81–88
Scheel M, Seemann R, Brinkmann M, Di Michiel M, Sheppard A, Breidenbach B, Herminghaus S (2008) Morphological clues to wet granular pile stability. Nat Mater 7:189–193. 10.1038/nmat2117
Scholtès L, Chareyre B, Nicot F, Darve F (2009) Micromechanics of granular materials with capillary effects. Int J Eng Sci 47:64–75. 10.1016/j.ijengsci.2008.07.002
Sleutel S, Cnudde V, Masschaele B, Vlassenbroek J, Dierick M, Van Hoorebeke L, Jacobs P, De Neve S (2008) Comparison of different nano- and micro-focus X-ray computed tomography set-ups for the visualization of the soil microstructure and soil organic matter. Comput Geosci 34:931–938. 10.1016/j.cageo.2007.10.006
Smethurst J, Clarke D, Powrie W (2012) Factors controlling the seasonal variation in soil water content and pore water pressures within a lightly vegetated clay slope. Géotechnique 62:429–446
Sonon B, François B, Massart TJ (2012) A unified level set based methodology for fast generation of complex microstructural multi-phase RVEs. Comput Methods Appl Mech Eng 223–224:103–122. 10.1016/j.cma.2012.02.018
Taina IA, Heck RJ, Elliot TR (2008) Application of X-ray computed tomography to soil science: a literature review. Can J Soil Sci 88:1–19. 10.4141/CJSS06027
Vijayan A, Annabattula RK (2019) Effect of particle flow dynamics on the fabric evolution in spherical granular assemblies filled under gravity. Powder Technol 356:909–919. 10.1016/J.POWTEC.2019.09.027
Vlahinić I, Andò E, Viggiani G, Andrade J (2014) Towards a more accurate characterization of granular media: extracting quantitative descriptors from tomographic images. Granul Matter 16:9–21. 10.1007/s10035-013-0460-6
Wang J-P, Andò E, Charrier P, Salager S, Lambert P, François B (2019) Micro-scale investigation of unsaturated sand in mini-triaxial shearing using X-ray CT. Géotechnique Lett 9:269–277. 10.1680/jgele.18.00214
Wang J-P, Li X, Yu H-S (2018) A micro–macro investigation of the capillary strengthening effect in wet granular materials. Acta Geotech 13:513–533. 10.1007/s11440-017-0619-0
Wang JP, Li X, Yu HS (2017) Stress-force-fabric relationship for unsaturated granular materials in pendular states. J Eng Mech 143:1–18. 10.1061/(ASCE)EM.1943-7889.0001283
Wang JP, Zeng GH, Yu HS (2019) A DEM investigation of water-bridged granular materials at the critical state. Comput Part Mech 6:637–655. 10.1007/s40571-019-00243-2
Wildenschild D, Sheppard AP (2013) X-ray imaging and analysis techniques for quantifying pore-scale structure and processes in subsurface porous medium systems. Adv Water Resour 51:217–246. 10.1016/j.advwatres.2012.07.018
Xu F, Liang S, Zhang Y, Li B, Hu Y (2021) Numerical study of water–air distribution in unsaturated soil by using lattice Boltzmann method. Comput Math with Appl 81:573–587. 10.1016/j.camwa.2019.08.013
