The shear strength of unsaturated granite residual soil (GRS) will decline rapidly when moisture content increases, because of loss of matric suction in the soil. This can lead to slope instability and embankment collapse during rainfall. Determining the matric suction of GRS accurately at different conditions can improve the accuracy of stability analysis. Generally, matric suction can be characterized as the soil–water characteristic curve (SWCC), and it is closely related to soil microstructure. In this study, the entire range of matric suction was measured using a combination of pressure plate method, filter paper method, and vapor equilibrium method. Microstructure change was investigated based on mercury intrusion porosimeter tests, in which the pore size distribution (PSD) curves of GRS samples with different initial densities and moisture content were measured. The PSDs of samples before and after wetting were also measured and compared to investigate the influence of water intrusion. Test results indicate that the combination of measurement methods can cover the entire matric suction range. The microstructure of GRS with different initial conditions presents a clear bimodal PSD. At the same density, the increase in initial moisture content can increase intra-aggregate pores and decrease inter-aggregate pores. When initial density increases, only the volume of inter-aggregate pores decreases. Wetting can decrease inter-aggregate pores and increase intra-aggregate pores. Finally, the Li model is applied in SWCC fitting for tested samples, the result of which performs well with a high correlation coefficient (R2 > 0.95) and is recommended for GRS analysis.
RahardjoH.LimT.ChangM.FredlundD.Shear-Strength Characteristics of a Residual Soil. Canadian Geotechnical Journal, Vol. 32, No. 1, 1995, pp. 60–77.
2.
RocchiI.CoopM.The Effects of Weathering on the Physical and Mechanical Properties of a Granitic Saprolite. Geotechnique, Vol. 65, No. 6, 2015, pp. 482–493.
3.
HeidemannM.BressaniL. A.GehlingW. Y. Y.FloresJ. A. A.PortoM. S.Influence of Structure in the Soil-Water Characteristic Curves of Two Residual Soils of Granite. In E3S web of conferences [recurso eletrônico]. [Les Ulis, França], Vol. 9, 2016, p. 11002.
4.
RaoS.RevanasiddappaK.Collapse Behaviour of a Residual Soil. Geotechnique, Vol. 52, No. 4, 2002, pp. 259–268.
5.
ZhaiQ.RahardjoH.SatyanagaA.DaiG.Estimation of Unsaturated Shear Strength from Soil–Water Characteristic Curve. Acta Geotechnica, Vol. 14, No. 6, 2019, pp. 1977–1990.
6.
YeY.-X.ZouW.-L.HanZ.LiuX.-W.Predicting the Entire Soil-Water Characteristic Curve Using Measurements Within Low Suction Range. Journal of Mountain Science, Vol. 16, No. 5, 2019, pp. 1198–1214.
7.
AntinoroC.ArnoneE.NotoL. V.The Use of Soil Water Retention Curve Models in Analyzing Slope Stability in Differently Structured Soils. Catena, Vol. 150, 2017, pp. 133–145.
8.
ZhangJ.NiuG.LiX.SunD.Hydro-Mechanical Behavior of Expansive Soils With Different Dry Densities Over a Wide Suction Range. Acta Geotechnica, Vol. 15, No. 1, 2020, pp. 265–278.
9.
GaoY.SunD.ZhouA.Hydromechanical Behaviour of Unsaturated Soil With Different Specimen Preparations. Canadian Geotechnical Journal, Vol. 53, No. 6, 2016, pp. 909–917.
10.
FeuerharmelC.GehlingW.BicaA.The Use of Filter-Paper and Suction-Plate Methods for Determining the Soil-Water Characteristic Curve of Undisturbed Colluvium Soils. Geotechnical Testing Journal, Vol. 29, No. 5, 2006, pp. 419–425.
11.
SunD.YouG.AnnanZ.DaichaoS.Soil–Water Retention Curves and Microstructures of Undisturbed and Compacted Guilin Lateritic Clay. Bulletin of Engineering Geology and the Environment, Vol. 75, No. 2, 2016, pp. 781–791.
12.
VanapalliS. K.FredlundD. G.PufahlD. E.The Influence of Soil Structure and Stress History on the Soil–Water Characteristics of a Compacted Till. Geotechnique, Vol. 49, No. 2, 1999, pp. 143–159.
13.
ZhouC.NgC. W. W.A New and Simple Stress-Dependent Water Retention Model for Unsaturated Soil. Computers and Geotechnics, Vol. 62, 2014, pp. 216–222.
14.
YaoY.NiJ.LiJ.Stress-Dependent Water Retention of Granite Residual Soil and Its Implications for Ground Settlement. Computers and Geotechnics, Vol. 129, 2021, p. 103835.
15.
ChengQ.NgC. W. W.ZhouC.TangC. -S.A New Water Retention Model that Considers Pore Non-Uniformity and Evolution of Pore Size Distribution. Bulletin of Engineering Geology and the Environment, Vol. 78, No. 7, 2019, pp. 5055–5065.
16.
RomeroE.SimmsP. H.Microstructure Investigation in Unsaturated Soils: A Review With Special Attention to Contribution of Mercury Intrusion Porosimetry and Environmental Scanning Electron Microscopy. Geotechnical and Geological Engineering, Vol. 26, No. 6, 2008, pp. 705–727.
17.
AnR.KongL.LiC.Pore Distribution Characteristics of Thawed Residual Soils in Artificial Frozen-Wall Using NMRI and MIP Measurements. Applied Sciences, Vol. 10, No. 2, 2020, p. 544.
18.
WangJ.-D.LiP.MaY.VanapalliS. K.WangX.-G.Change in Pore-Size Distribution of Collapsible Loess due to Loading and Inundating. Acta Geotechnica, Vol. 15, No. 5, 2020, pp. 1081–1094.
19.
OualmakranM.MercatorisB.FrançoisB.Pore-Size Distribution of a Compacted Silty Soil After Compaction, Saturation, and Loading. Canadian Geotechnical Journal, Vol. 53, No. 12, 2016, pp. 1902–1909.
20.
ASTM. Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System). ASTM International, West Conshohocken, PA, 2020.
21.
ASTM, Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted Soils. ASTM International, West Conshohocken, PA, 2016.
22.
BhuyanH.ScheuermannA.BodinD.BeckerR.Use of Time Domain Reflectometry to Estimate Moisture and Density of Unbound Road Materials: Laboratory Calibration and Field Investigation. Transportation Research Record, Vol. 2655, No. 1, 2017, pp. 71–81.
23.
LikosW. J.LuN.Filter Paper Technique for Measuring Total Soil Suction. Transportation Research Record, Vol. 1786, No. 1, 2002, pp. 120–128.
24.
YangS.-R.HuangW.-H.TaiY.-T.Variation of Resilient Modulus With Soil Suction for Compacted Subgrade Soils. Transportation Research Record, Vol. 1913, No. 1, 2005, pp. 99–106.
25.
ASTM. Standard Test Method for Measurement of Soil Potential (Suction) Using Filter Paper. ASTM International. West Conshohocken, PA, 2016.
26.
DelageP.HowatM.CuiY.The Relationship Between Suction and Swelling Properties in a Heavily Compacted Unsaturated Clay. Engineering Geology, Vol. 50, No. 1–2, 1998, pp. 31–48.
27.
BlatzJ. A.CuiY.-J.OldecopL.Vapour Equilibrium and Osmotic Technique for Suction Control. Geotechnical and Geological Engineering, Vol. 26, No. 6, 2008, pp. 661–673.
28.
SasanianS.NewsonT.Use of Mercury Intrusion Porosimetry for Microstructural Investigation of Reconstituted Clays at High Water Contents. Engineering Geology, Vol. 158, 2013, pp. 15–22.
29.
KodikaraJ.BarbourS.FredlundD.Changes in Clay Structure and Behaviour due to Wetting and Drying. In Proc., 8th Australia New Zealand Conference on Geomechanics: Consolidating Knowledge, Australian Geomechanics Society. Barton, ACT, Australia, 1999, p. 179.
30.
LiX.ZhangL.Characterization of Dual-Structure Pore-Size Distribution of Soil. Canadian Geotechnical Journal, Vol. 46, No. 2, 2009, pp. 129–141.
31.
ZhangL.LiX.Microporosity Structure of Coarse Granular Soils. Journal of Geotechnical and Geoenvironmental Engineering, Vol. 136, No. 10, 2010, pp. 1425–1436.
32.
GaoY.SunD.WuY.Volume Change Behaviour of Unsaturated Compacted Weakly Expansive Soils. Bulletin of Engineering Geology and the Environment, Vol. 77, No. 2, 2018, pp. 837–848.
33.
ThomR.SivakumarR.SivakumarV.MurrayE.MackinnonP.Pore Size Distribution of Unsaturated Compacted Kaolin: The Initial States and Final States Following Saturation. Geotechnique, Vol. 57, No. 5, 2007, pp. 469–474.
34.
OtalvaroI. F.NetoM. P. C.DelageP.CaicedoB.Relationship Between Soil Structure and Water Retention Properties in a Residual Compacted Soil. Engineering Geology, Vol. 205, 2016, pp. 73–80.
35.
MitchellJ. K.SogaK.Fundamentals of Soil Behavior. John Wiley & Sons, New York, 2005.
36.
WanA.GrayM.GrahamJ.On the Relations of Suction, Moisture Content and Soil Structure in Compacted Clays. Proc., 1st International Conference on Unsaturated Soils, Paris, France, 1995. A. A. Balkema, Rotterdam, The Netherlands, pp. 215–222.
37.
YingZ.CuiY. -J.BenahmedN.DucM.Changes in Microstructure and Water Retention Property of a Lime-Treated Saline Soil During Curing. Acta Geotechnica, Vol. 17, No. 1, 2022, pp. 319–326.
38.
LiX.LiJ. H.ZhangL. M.Predicting Bimodal Soil–Water Characteristic Curves and Permeability Functions Using Physically Based Parameters. Computers and Geotechnics, Vol. 57, 2014, pp. 85–96.
