Post Grouted Drilled Shafts — A Comprehensive Case History from Texas

Abstract

Post-Grouted Drilled Shafts (PGDS) are a deep proprietary foundation system in which grout is injected at high pressure through the tip after the drilled shaft has been installed. The improved ultimate load capacity and stiffness of PGDS compared to conventional drilled shafts are believed to be related to the pre-stressing effect which the tip post grouting has on the shaft side friction due to the generated upward movement, and the grout bulb formed at the PGDS tip which results in an enlarged tip area and also pre-compresses the soil beneath the tip as well as any disturbed material generated during construction. This paper presents results of a comprehensive full-scale load test program at the clay and sand sites of the well characterized Texas A & M NGES. The test program involved conventional static load tests as well as O-cell tests on PGDS foundations and conventional drilled shafts installed and tested under similar conditions. Copyright ASCE 2009.