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Estimating water retention curves and strength properties of unsaturated sandy soils from basic soil gradation parameters
Author(s) -
Wang JiPeng,
Hu Nian,
François Bertrand,
Lambert Pierre
Publication year - 2017
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2017wr020411
Subject(s) - gradation , pedotransfer function , cohesion (chemistry) , water retention , water retention curve , soil water , geotechnical engineering , degree of saturation , soil gradation , soil science , saturation (graph theory) , extrapolation , mathematics , hydraulic conductivity , materials science , environmental science , geology , statistics , chemistry , organic chemistry , combinatorics , computer science , computer vision
This study proposed two pedotransfer functions (PTFs) to estimate sandy soil water retention curves. It is based on the van Genuchten's water retention model and from a semiphysical and semistatistical approach. Basic gradation parameters ofd 60as particle size at 60% passing and the coefficient of uniformityC uare employed in the PTFs with two idealized conditions, the monosized scenario and the extremely polydisperse condition, satisfied. Water retention tests are carried out on eight granular materials with narrow particle size distributions as supplementary data of the UNSODA database. The air entry value is expressed as inversely proportional tod 60and the parameter n , which is related to slope of water retention curve, is a function ofC u. The proposed PTFs, although have fewer parameters, have better fitness than previous PTFs for sandy soils. Furthermore, by incorporating with the suction stress definition, the proposed pedotransfer functions are imbedded in shear strength equations which provide a way to estimate capillary induced tensile strength or cohesion at a certain suction or degree of saturation from basic soil gradation parameters. The estimation shows quantitative agreement with experimental data in literature, and it also explains that the capillary‐induced cohesion is generally higher for materials with finer mean particle size or higher polydispersity.