October 2, 2019 ITS Money: John Turner, Ph.D., P.E., D.GE

John Turner, Ph.D., P.E., D. GE | Dan Brown and Associates, PC

Cost Benefits of Drilled Shaft Load Testing

Design, testing, and construction of rock-socketed drilled shaft foundations for the Fore River Bridge in Massachusetts is presented. This case history illustrates the beneficial use of load testing for optimization of rock socket design and construction. Load testing allowed the design-builder to decrease rock socket lengths compared to original estimates by demonstrating that significant side and base resistance can be achieved even in highly fractured rock mass when construction means and methods are selected to match the ground conditions.

Findings

• Load testing has obvious cost benefits related to design, in the examples presented here by reducing the length of large-diameter rock sockets; higher resistance factors.
• A not-as-obvious cost benefit often exists when load test results can be used to address problems that arise during construction or when load testing provides an opportunity to control construction risks.