The engine for developing a constitutive model for soil is based on fundamental stress-strain relationships in the soil. This lecture introduces you to the basic concepts of understanding stress-strain in soil, both in 2D and 3D. Volumetric and deviatoric strains are discussed, as well as the use of invariants to predict these strains. Various methods to measure or "guesstimate" the proportionality constants (e.g., elastic moduli and Poisson's ratio) for the soil are discussed.

Make sure to watch the next bonus lecture on using dynamic and geophysical methods to measure proportionality constants as well (......so that my friends Dr. Brady Cox and Dr. Clint Wood don't get mad at me hahaha).