STUDY ON INFLUENCE OF SOIL-PILE NONLINEAR INTERACTION ON VEHICLE-BRIDGE COUPLING VIBRATION

Based on the beam on a Winkler foundation, a modified P-Y curve method and a load-transfer hyperbolic model are used to build the model of nonlinear pile-soil interactions. The relative stiffness of the pile and soil is adopted to calculate the horizontal initial stiffness of pile-soil interactions. The ultimate soil resistance is obtained by Mohr-Coulomb failure criterion. According to Matlock P-Y curve method, the expression of the ultimate soil resistance is improved, thusly the depth effect of the ultimate soil resistance is fully considered. The pile-soil nonlinear finite-beam element analysis program is compiled on the basis of these models. The vehicle-bridge coupling model considering nonlinear pile-soil interactions is built and applied to determine the behavior of a bridge in practice. The vehicle-bridge coupling vibration considering nonlinear pile-soil interactions is analyzed and compared with previous pier bottom consolidation models. The results show that the horizontal displacements of the bridge considering the nonlinearity of pile-soil interactions increase significantly in the process of a coupled vibration between a high speed railway bridge and a vehicle. The vertical displacements of the bridge increase. The accelerations of the bridge reduce. These results provide the parameters to the design of a high speed railway bridge located in soft ground with a high-pile cap foundation.