Shaking table test of model foundations in saturated sand

Abstract

In Japan and Turkey, predominantly traditional design concept of pile group is still adopted even though most pile foundations are piled raft foundations in reality. This situation may be attributed to the still limited knowledge about behavior of piled rafts subjected to vertical loads and dynamic loads, especially in saturated soil. Hence, in this study, a series of shaking table tests on 3-pile piled raft (PR), 3-pile pile group (PG) models were carried out in saturated sand under the combinations of vertical and dynamic (horizontal shaking) loading, where the input motion was sinusoidal wave having a frequency of 20 Hz and a magnitude of 1.50 m/s². The results showed that, raft-ground contact in PR is very effective to reduce settlement compared to PG even in liquefied ground. Moreover, even in PR, the horizontal resistance reduces if liquefaction of the ground surface occurs, due to the loss of the raft base resistance. It can be concluded that PR is an effective, economical and safe foundation type even in shaking loading, compared to conventional pile group. In cases of liquefiable soils or soft soils, PR with soil reinforcement or soil improvement near the ground surface will be a practical solution.