Proceedings-DFI/EFFC 11th International Conference on Piling and Deep Foundations, 2014, Stockholm, Sweden, (DFI)
The Use of the Expander Body with Cast In Situ Piles in Sandy Soils
Mario A. Terceros H., Incotec SRL, Bolivia; K. Rainer Massarsch, Geo Risk & Vibration Scandinavia, Sweden
The Expander Body (EB) technology has been used successfully to increase the pile toe capacity of bored piles in loose to medium dense soil. An important advantage of the EB system is the ability to monitor the EB expansion process, which provides important information regarding soil strength and soil stiffness. This information, obtained for each installed pile, can be used to determine the actual shape and pile toe area. The expansion pressure can be used to design the pile base capacity. The Expander Body system has been recently improved by incorporating the possibility of postgrouting of the soil below the expanded pile toe. This improvement measure provides additional strength and stiffness to the pile toe and reduces pile settlement. The shaft bearing capacity of bored piles can be increased by using a soil displacement auger, which avoids soil decompression and increases lateral soil stress. This paper describes the principle of the EB system. During the past 20 years, a large number of EB piles have been installed in Bolivia and elsewhere, providing a sound database. Results from field loading tests are presented. A comprehensive study of test piles with and without EB base has been carried out which demonstrates the improvement effects that can be achieved by the EB pile system and the combination with the displacement auger pile method. A design concept for the EB pile system with the full displacement auger pile is presented. A high degree of quality control can be achieved by monitoring the entire pile installation process, including the displacement pile and the Expander Body.
|article #1911; publication #100 (IC-2014)|