Shaking Table Tests Of Piles-Soil-Structure Interaction System

In this paper, the shaking table tests of branch piles-soil-structure dynamic interaction system were designed. The same similar relation should be stand by piles, soil and structure. Soil box and the experiment apparatus were selected according to the requirement of shaking table and boundary conditions, and the working drawings of the system pursuant to the similar relation was designed. The experiments of branch piles-soil-structure system have been done in shaking table testing division of state key laboratory for disaster reduction in civil engineering, Tongji University.Through analyzing the data of shaking table test of dynamic pile-soil-structure interaction (SSI) system, the interaction laws and effects of branch-piles are studied. Discussion on the following points: interactions cause the changes of dynamic characteristics of the system including natural period and damping ratio. The system natural frequency became smaller, damping ratio became larger, and the interbedded shear and overturn torque were smaller than the normally rigid structure on the foundation , but the top displacement was lager than the rigid foundation of the structure; the vibration spectrum characteristics was changed, the laws of piles strain and contact stress between piles and soil.When input small earthquake wave, pile-soil system makes the wave large. And if input big earthquake wave, pile-soil system will reduce the energy of the earthquake wave. When the earthquake wave transfers from the surface of shaking table to the surface of the soil, the spectral component of the earthquake wave is changed by pile-soil system.The strain of upper piles is large,and the strain of bottom part is small.Test results show that the branch pile can be effective in improving the capacity of shock absorption, lowering the reaction of upper structure under earthquake. It has a great significance in withstanding earthquakes and reducing the earthquake.