Effective and Suction Stresses of Unsaturated Pendular-State Granular Soils

A micro-mechanical analysis is used to evaluate the suction and effective stresses of unsaturated granular soils in a pendular state. The discrete element method was used to model the soil particles. These particles are subjected to inter-particle forces as well as suction forces exerted by pendular water bridges that form at the inter-face of particles that are in contact or in close proximity. The suction forces are evaluated using a toroidal approximation to the water bridges. Computational simulations and analytical derivations were used to develop an expression providing the suction and effective stresses within pendular-state unsaturated granular soils. Suction stresses were found to be a direct function of porosity, water content, and water bridge coordination number and fabric tensor.