Publication Abstract

Proceedings - Seventh International Conference & Exhibition on Piling and Deep Foundations, 1998, Vienna, Austria, (DFI)

Bored Piles in Jeddah Coral Formation
Alp Gokalp, Erdogdu Savaskan

For a new international hotel complex under construction in Jeddah, Saudi Arabia, 919 piles have been installed so far. This case history describes installation of those skin and base grouted, bored, cast-in-place piles, and discusses their performance. The foundation soil is composed of coralline limestone of widely varying strength, as well as silty sand derived from this formation. The coralline limestone has largely preserved the unique skeletal structure of coral reef and is therefore very erratic. Apart from its varying strength, the coralline limestone is characterized by irregular cavities, which are a major concern for the foundations. The pile type designed for the project is a bored, cast-in-place pile of 1000mm diameter and 20m effective length, having an allowable bearing capacity of 3750kN. The piling method adopted for the hotel complex consists of cavity probing at each pile location; grouting or alternative measures in case cavities are detected below pile toe level; installation of bored piles with pile base and skin grouting; and integrity testing. For cavity probing, continuous dynamic cone penetration testing was adopted. A number of static pile loading tests have been performed to verify allowable load bearing capacity of the designed pile.

 article #339; publication #34 (IC-1998)