DYNAMIC BEHAVIOR OF PILE GROUP CONSIDERING SOIL-PILE-CAP I NTERACTION

摘要

It is well known that the earthquake response of a pile-supported structure is strongly affected by the dynamic soil-pile interaction. In the case of weak soils or severe ground motions, group piles are often the suitable solution. In most practical cases the pile cap is sitting on the ground as well as the piles in the group. The contact between the pile cap and supporting pile is simply neglected in practice. However, with advent of fast computers, geotechnical researchers would like to reach precise and rigorous solutions. Therefore, in this research, a finite element model to take into account soil-pile-cap interaction for dynamic loads is developed.The proposed model for the soil-pile-cap (SPC) system consists of structural elements to represents piles and concrete cap, brick elements representing the soil and interface element to model the contact surfaces between soil-pile and soil-cap. Seismic response of the system is found using an explicit successive-coupling incremental solution scheme. Material nonlinearity of soil is also introduced into the model. Proper absorbing boundary conditions, simulating radiation effects are used. Developing a comprehensive study, a series of numerical analyses using dynamic finite element method are conducted to investigate affecting parameters on dynamic behavior of group-pile foundation. Along with the effect of pile-soil-cap interaction, the piles slenderness, type of piles, piles space and embedment of the pile cap is also studied. The results showed that neglecting the pile-soil-cap interaction in dynamic analysis of pile groups could lead to non-exact results in terms of the pile group response.