Effective Stress of Unsaturated Granular Soils in a Pendular State

Abstract

A micromechanical model is used to asses the impact of inter-particle water bridges on the stress condition of unsaturated pendular-state granular soils. The discrete element method was employed to idealize the soil skeleton. Suction forces were used to model the effects of pendular water bridges. These bridges develop at interparticle contacts mostly as a function of soil water content and particle size and shape. Numerical simulations were used along with analytical derivations to develop an expression providing the suction and effective stresses within unsaturated pendular-state granular soils. Suction stresses were found to be a direct function of porosity, water content, water bridge coordination number, and water bridge fabric tensor.