Constructability for drilled shafts

Principles of constructability are applied to the planning, design, and construction of drilled-shaft foundations. It is shown that the keys to drilled-shaft constructability are an appropriate site investigation, the knowledge and experience of civil engineers with drilled-foundation construction procedures, and a quality-control program. Methods of drilled-shaft construction are reviewed and specific procedures for implementing constructability during site investigations are presented. The input of engineers experienced in drilled-shaft construction is shown to be necessary for successful cost estimates, accounting for effects of construction on design assumptions, and in developing rational construction specifications, all of which are critical for applying constructability to drilled shafts. Quality control, through inspection and nondestructive testing, can increase the reliability of drilled shafts by verifying subsurface conditions and by providing evaluation of postconstruction integrity. Two case histories are used to demonstrate that constructability provides a useful management and engineering tool to reduce foundation costs and increase reliability.