Seismic Analysis Of High-Speed Railway Bridges Considering Soil-Pile Foundation Interaction

According to the current seismic design code for bridge of high speed railway, the destruction is generally considered to occur in the pier, and the destruction of pile foundation is not considered. However, by summarizing seismic data in recent decades at home and abroad, we can see many bridges destroyed because of failure of pile foundation. In the study, based on a lot of relevant information, a deep research on pier-pile system is given. The main work is as follows:(1) In this paper, soil-structure interaction history and development status are summarized. The Seismic Soil-structure interaction of the basic mechanisms, the soil-structure interaction method, soil-pile-structure interaction model commonly used in engineering, and a number of important issues about soil pile interaction are discussed.(2) To consider the interaction between pile and soil under horizontal load, combined with domestic and foreign design specifications, this paper puts forward the single pile foundation calculation model based on the p-y curves (including the t-z curve, q-z curve) method of and verifies the accuracy and applicability of p-y curve method through the field test data, and the effect on the mechanical behavior of pile foundation when the soil parameters (clay undrained shear strength and bulk density, soil friction angle and bulk density) change is discussed.(3) The calculation model of nonlinear static pile group applied to the high-speed rail bridge is presented, in which the simulation method of nonlinear pile foundation is considered. Based on the nonlinear static calculation model of group pile foundations, the main parameters affecting nonlinear performance of pile foundations are analyzed. The failure mode, deformability, load capacity and distribution of pile internal force under the action of horizontal loading at the top of the pier are studied, and pile foundation bearing capacity, displacement ductility factor, the pile of plastic hinges generation mechanism and the influence of the development process are summarized when the parameters (pier height, pile diameter, pile reinforcement ratio, pile stirrup ratio) change.(4) The pier-pile system is analyzed by capacity spectrum method. It provides the basic principle and implementation steps of Pushover analysis method and capacity spectrum method; and summarizes the construction method and the method for solving the corresponding performance points of the two types of elastoplastic constructor demand spectra. It proposes bending shear numerical model in which the pier transverse shear effect is considered. With bending spring to simulate structure of bending deformation and ultimate bearing capacity and shear spring to simulate structure of shear deformation, the pier bending shear effect is considered through the coupling of the two; and the effectiveness is verified by the test data. Through using elastoplastic demand spectrum based on ductility coefficient and Zhao Guanyuan Ry-u-Tn relationship model, the pier-pile system is analyzed by capacity spectrum method. Comparing the results of capacity spectrum method with the results of nonlinear time history analysis, we can know that the error is within the permissible range, which verifies the accuracy of capacity spectrum method proposed in this paper when it is used to solve target displacement.(5) The seismic performance based on ductility of the pier pile system is analyzed. It puts forward judgement methods for different failure types of bridge pier pile system, and methods to analyze seismic performance in the different failure types; for the destruction of the pier body, structure to improve stiffness degradation model and Park-Ang double parameter model are used to calculate the structure of the damage, and it also proposes the quantitative relationship between damage levels and damage index; for the underlying structure, the reaction rate and the level of injury member plasticity seismic performance of the structure analysis. An example is given which studies the influence of reinforcement ratio on pier pile system failure type.