Nanoscale soil-water retention curve of unsaturated clay via molecular dynamics

¹ PhD Candidate, Engineering School of Sustainable Infrastructure & Environment, University of Florida, USA
² Associate Professor, Engineering School of Sustainable Infrastructure & Environment, University of Florida, USA

Abstract

This paper characterizes nanoscale soil-water retention mechanism of unsaturated clay through molecular dynamics simulation. Series of molecular dynamics simulations of clay at low degrees of saturation were conducted. Soil water was represented by a point cloud through the centre-of-massmethod. Water-air interface area was measured numerically by the alpha shape method. Spatial variation of water number density is characterized and used to determine the adsorbed water layer. The soil-water retention mechanism at the nanoscale was analysed by distinguishing adsorptive pressure and capillary pressure at different mass water contents and considering apparent interface area (water-air interface area per unit water volume).