METHODOLOGY FOR DESIGN AND CONSTRUCTION OF DRILLED SHAFTS IN COHESIVE SOILS.

Drilled shaft foundations are widely used in the construction of numerous types of permanent structures such as buildings, residences, bridges, and towers in unstable materials and fills including swelling soils. Much research has been done to develop design procedures for drilled shaft foundations, but few comparisons had been made to validate the design methodologies for different soils and loading conditions. This report presents a comprehensive evaluation of different design procedures and describes those procedures that offer satisfactory solutions to the design of shaft foundations. Guidelines are provided for the design and construction of drilled shaft foundations subject to axial and lateral loading forces using either effective or total stress analysis. Axial load resistance is provided by skin and end bearing resistance. An appropriate maximum skin resistance may be calculated by using the cylindrical shear model with the soil strength reduced to compensate for remolding and softening of the soil. Refs.