Review on the methods to reduce negative skin friction.
Phooi, Keng Loong.
Date of Issue1998
School of Civil and Environmental Engineering
The first part of this report reviews factors that initiate downdrag and the relationship between skin friction, the pile and soil. The next section summarises various methods that have been used for the computation of downdrag such as the theoretical solution method and empirical methods based on field observation and model tests. A commonly used method for computation of downdrag for single pile and pile in groups together with the foundation design consideration for piles subjected to downdrag is also included. This is follow by the literature review covering the various methods that have been used for downdrag reduction on end bearing piles in full-scale field tests and laboratory experiments. For each of the method reviewed, the principle, method of installation, effectiveness, cost and construction difficulties together with a discussion of the results obtained from the full scale testing or laboratory experiment is presented. Finally, a hypothetical study for foundation design on a soil profile taken from Tuas, Singapore using three different types of piles, namely the precast driven, bored cast in-situ and composite pile is included. The purpose of this study is to investigate the savings in foundation costs with downdrag reduction applying one of the methods discussed above to the composite pile.