EXPERIMENTAL MODELING OF THE SHAFT CAPACITY OF GROUTED DRIVEN PILES

Pile foundations are widely used in compressible soils such as calcare ous sediments. However, the friction capacity of driven piles in such soils tends to be very low, owing to severe reduction of the normal ef fective stresses at the pile-soil interface during installation of the pile, caused by densification of the soil. The shaft capacity may be increased by injection of grout along the pile-soil interface, referre d to as ''grouted driven pile'' construction. A new apparatus for test ing such a type of pile has been developed at the University of Wester n Australia. In this paper, the design of the apparatus and associated model piles are described, along with the grouting technique. Limitat ions of early versions of the apparatus and difficulties with grouting at small scale are discussed, and recommended solutions are presented . Results of tests performed on specimens of calcareous soils that wer e artificially cemented in order to reproduce typical in situ strength s are also presented.