Comparison Tests Of Seismic Soil-Pile-Structure Interaction In Liquefiable And Nonliquefiable Soil

The pile foundation damages in liquefiable soil often have occurred during a number of major earthquakes in recent years. Pile foundation damage was a terrible hazard which can result in collapse of superstructure of bridge. After that, traffic was disrupted, secondary disasters followed. Therefore, the study on pile-soil-structure interaction in liquefiable soil become important subject in seismic design of foundation in bridge engineering in the world.Though many seismic design methods of pile foundation were put forward, there are obvious deficiencies in seismic design method of piles in liquefiable site for methods used at present. One of the main causes is lack of understanding to mechanism of liquefied-related pile-soil interaction. Except of that, some methods have not been verified by physical data of post-earthquakes or model tests.Given liquefaction, even serious liquefaction in the site of Xiazhang bridge, a project of pile-soil-structure interaction is produced, which is a subproject of seismic design and model test of Xiazhang bridge. In this paper, based on the subproject, five shaking table tests of pile-soil-structure interaction in liquefiable and nonliquefiable soil, including FF(free-field) test, LLR(liquefiable-layer-removed) test, NLF (nonliquefiable-field) test, SF (sandwich field ) test, NSF(Non-sandwich field) test, are designed.The main contents and achievements of this dissertation are described as follows:1. Based on a lot of literatures at home and abroad, the analytical methods and tests about the issue of pile-soil-structure interaction was summarized;2. The pile-soil interaction shaking table test in LLR and SF field is completed, a lot of data was obtained and processed;3. After data processing of LLR test and SF test, the author analysized the results of strain data in different load cases and with different bandpass filtering;4. According to the outcome of tests, regardless soil kinematic interaction, even through the use of"no-strength"approach is not appropriate for seismic design of piles in laterally spreading ground;5. Some suggestions for the project were put forward.