2017 年 5 巻 1 号 p. 357-376
Some level of settlement is allowed in the design of oil tanks if uneven settlement is controlled within allowable values. Considering the critical condition of piled raft foundation (PRF), that is, secure contact of raft base to the ground surface, PRF is considered one of the rational foundations for the oil tanks. However, PRF has a complex interaction with soil under horizontal seismic loading, especially if the tank rests on a liquefiable soil. On the other hand, the pile installation method can affect the pile bearing capacity and the liquefaction resistance of sand as well. In this study, a series of centrifuge tests was performed to investigate the mechanical behavior of oil tanks supported by PRF on liquefiable sand. In the tests, slab and piled-raft foundations were modeled. In the case of PRF, two different methods of pile installation (Driven and Non-Driven) were modeled and the Driven PRF models were made with two different pile numbers. Using the observed results, such as accelerations of the tank and ground, displacements of the foundation and excess pore water pressures of the ground, advantages, and limitations of PRF for oil tanks on liquefiable sand are discussed.
