ABSTRACT
Soil is an assemblage of particles so that the soil’s skeleton (particle connected structure) is a major body to resist against external forces. This is seen in Figure 7.1, in which two-headed arrow vectors indicate interparticle forces at contact points, including normal contact forces as well as shear contact forces. In a dry situation, interparticle forces are in equilibrium with the external forces as seen. However, if the soil is saturated or partially saturated, pore water pressure develops, and it also resists against some part of the external forces.
