Abstract

An experimental investigation on the coefficient of earth pressure of overconsolidated cohesionless soil developed around displacement piles was conducted. An instrumented
prototype set-up and model pile was developed in the laboratory. The set-up was capable of measuring the total load, the shaft resistance acting on the pile and the
overconsolidation ratio in the sand mass. Overconsolidated sand was prepared by placing the sand in the testing tank in layers, each subjected to a predetermined compaction
effort. The stresses in the sand mass were measured by means of pressure transducer units placed in selected locations in the testing tank. The model piles were driven into the sand mass to a selected depth. Pile load tests were conducted at a constant rate of penetration at different depths.
The pile capacity was determined from load-displacement curves. The shaft resistance and, hence, the coefficient of earth pressure around the pile were determined. The results
showed that the coefficient of earth pressure is heavily dependent on the stress history of the sand mass. A theoretical model was developed to incorporate the effects of overconsolidation of the sand on the shaft resistance of driven piles in cohesionless soils.