Abstract: A series of centrifuge model tests were conducted on the spatial distribution characteristics of stress and pore pressure due to pile installation. According to test data, the existing cavity expansion theory was modified, and a pile installation model, which took ground surface heave into account, was proposed. The reliability of this model was validated by the centrifuge test data. The results showed that variation characteristics of total radial stress and the pore-water pressure were controlled by the distance from the pile axis and depth of the soil element. For a certain depth, the stress and pore-water pressure of soil increased as the pile tip reached and decreased as the tip passed. For the same distance from pile, the increases of stress and pore-water pressure caused by deep penetration were larger than those induced by shallow penetration. The reason was that the free ground surface influenced the stress conditions. If the pile penetration depth in the silty clay reaches 7~7.5 times pile diameter, the influences can be ignored. The studies of this paper will provide the basis for time-dependent prediction of pile foundation capacity.

Key words: centrifuge model test, total stress, excess pore pressure, pile jacking