4.1 INTRODUCTION

Spread footings and mat foundations are generally classified as shallow foundations. These foundations distribute the loads from the superstructures to the soil on which they are resting. Failure of a shallow foundation may occur in two ways: (1) by shear failure of the soil supporting the foundation, and (2) by excessive settlement of the soil supporting the foundation. The first type of failure is generally called bearing capacity failure. The second type of failure may be due to excessive elastic or elastic and consolidation settlement. The procedures for calculation of elastic and consolidation settlements of a foundation can be found in many books [see Das, 1983) and will not be discussed in detail primarily due to lack of space. Instead, this chapter will summarize a number of bearing capacity theories available in literature at the present time.