ABSTRACT
This chapter compares and contrasts foundation design on rock and soil. A traditional soil foundation approach based on plane plastic strain and limit load theorems is outlined. Foundation designs on rock and soil have some similarities but also important differences. Both share elasticity theory as a starting point for rational design and both often show nonlinearities under load. Distributions of displacements are of critical importance, of course, when design criteria are given in terms of limiting displacements. Design analysis for foundations on jointed rock requires a numerical approach to the solution of the governing system of equations generated from physical laws, kinematics and material behavior. Elastic-plastic analysis of a strip footing under a uniformly distributed load leads to a distribution of stress below the strip in the shape of a "pressure bulb". The finite element method used for computations automatically takes the joints with the computation of equivalent properties and by tracking stress states in joints and intact rock separately.
