Research On The Numerical Analysis Model Of The Soil-Pile-Structure Interaction With Gaping Considered

Bored pile foundation is widely used in Chinese high-speed railway bridges. Under strong seismic excitation, nonlinearity of the soil medium and separation at the soil-pile interface can have significant influence on the response of the pile. Various authors have incorporated the nonlinear effects of the pier into pile foundation seismic design,but the research on the nonlinear of the pile and soil in railway pile foundation seismic design is insufficient. In view of structural and mechanical characteristics of bored pile foundation under high-level earthquake, this paper attempt to propose a numerical analysis model that can accurately simulate the nonlinear behavior of the soil and the discontinuity conditions at the soil-pile interface. The main research contents are as follows:(1) On the base of the classification and summary of the analysis model of the soil-pile structure, this paper discusses the advantages and disadvantages of the existing models.(2) Introduces the constitutive model of the Elasto-plastic dynamic analysis and the process of the establishment and solving of the motion equation.(3) Develops an analysis model to study the soil-pile-structure interaction in cooperating nonlinear soil behavior and soil-pile interaction based on an engineering example of the standard 32 m span simply supported bridge. Study the influence axial compression, ultimate friction of the medium clay soft, the internal friction angle of the middle dense medium sand and the mass of the reference soil on the seismic response of the pile foundation.(4) The tensionless bilinear spring element is adopted to simulate the separation and sliding at the soil-pile interface. The comparative analysis is performed to discuss the effect of the gap and siding at the soil-pile interface on the different soil layers.