Allowable Eccentricity of Pile Groups for Deep Basements

Abstract

Basement excavation will cause installed piles to move laterally. It is very common for driven piles in developments with two-level basements to have large eccentricities from their intended positions at the cut-off level of the piles. However, this naturally occurring phenomenon is not well recognized in the construction industry. This is evident from the fact that the allowable pile eccentricity specified in many technical specifications for developments with basements is fixed at 75 mm, which normally is specified for pile foundations of developments with no basement construction. This paper used a case study to illustrate the extent of such pile lateral movements as a result of basement excavation. The effect of such lateral movements on the pile foundation design was discussed using the case study. Appropriate allowable pile eccentricity for driven piles for developments with deep basements are proposed.