Evaluation of Axial Capacity of Post Grouted Drilled Shafts

Abstract

A design phase load test program was performed at the Broadway Viaduct bridge site to evaluate load carrying capacity and constructability of post grouted drilled shafts. Three strain gauge instrumented test drilled shafts were installed in medium dense sand. Two drilled shafts included sleeve port and plate base grouting apparatus and were post grouted. The third drilled shaft was un-grouted and served as a control drilled shaft for comparison of the un-grouted end bearing. All drilled shafts were 1.52 m (5 feet) in diameter. The control drilled shaft was 16.76 m (55 feet) long. Post grouted drilled shafts were 16.76 m (55 feet) and 20.12 m (66 feet) long. The three drilled shafts were tested including integrity testing using the crosshole sonic logging method on each shaft, post grouting, and statnamic load testing. The test results were used to evaluate the axial capacity increase and an existing design method for post grouted drilled shafts.