Lateral Loading Tests on Piled Rafts and Simplified Method to Evaluate Sectional Forces of Piles

Abstract

Both analytical and experimental studies are necessary when developing a seismic design concept for piled raft foundations, especially in highly active seismic areas such as Japan. This paper presents static cyclic lateral loading tests on large-scale piled raft foundations carried out to investigate the influence of vertical load and pile spacing ratios during earthquakes. The test models were pile groups and piled rafts with a concrete footing supported by 16 piles in a 1g field. The results showed that most of the lateral force was carried by raft friction when there was large contact earth pressure beneath the raft, and that piles experienced pulling forces from the raft, behaving like anchors at large deformations. The tested foundations were simulated using a simplified method based on Mindlin’s solution, with theoretical equations derived making some approximations and assumptions. The simulated results agreed well with the test results.