Post-Grouting of Long Bored Piles in Clay

As a remedial measure to mitigate the construction flaws, the application of post-grouting technique to bored piles in cohesionless soils has received considerable attention. However, much fewer cases were reported for its application to bored piles in clays. In this study, a long and large diameter bored pile (90 m in length and 1000 mm in diameter) in the thick clayey soil deposits was treated with post-grouting and static axial compression load tests were conducted on this grouted and another ungrouted pile in the same diameter and length. The comparison of their axial loading behaviors demonstrated that after the post-grouting treatment, the axial pile load capacity was increased by 100% more. For long bored piles, the majority of pile axial load capacities derived from mobilization of pile side resistance. The contribution of pile tip resistance to the overall pile bearing capacities was negligible, regardless of whether long bored piles were post-grouted or not.