Estimating water retention curves and strength properties of unsaturated sandy soils from basic soil gradation parameters. Issue 7 (25th July 2017)

• Record Type: Journal Article
• Authors: Wang, Ji‐Peng; Hu, Nian; François, Bertrand; Lambert, Pierre
• Is Part Of: Water resources research. Volume 53:Issue 7(2017)
• Page Start: 6069
• Page End: 6088
• Publication Date: 2017-07-25
• Subjects: pedotransfer function -- particle size distribution -- water retention curve -- suction stress -- shear strength -- cohesion; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2017WR020411
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: 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 of d 60 as particle size at 60% passing and the coefficient of uniformity C u are 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 to d 60 and the parameter n, which is related to slope of water retention curve, is a function of C 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. Key Points: Pedotransfer functions are proposed to estimate WRC from two basic soil gradation parameters (d10 and Cu ) through a semiempirical approach With physical features considered, the model with fewer and more easily obtained parameters shows good performance in WRC prediction By incorporating with the suction stress definition, it provides a preliminary estimation of strength properties from grain size