Study On Influence Of Soil-pile Nonlinear Interaction On Vehicle-bridge Coupling Vibration

The calculation method of vehicle-bridge coupling vibration has become animportant way of evaluating the dynamic design parameters of the high speed railwaybridge. It is the key problem for the calculation of vehicle-bridge coupling vibration toestablish the accurate model. For the interaction of railway bridge and vehicle, theinfluent factors of its dynamic characteristic are include the pile foundation inaddition to the upper structures. At present, there are few researches of vehicle-bridgecoupling vibration considering nonlinear interaction of pile and soil. In fact, there arerestriction of deformation and energy transfer between the pile and soil under thedynamic loads. Therefore, the study of vehicle-bridge coupling vibration consideringnonlinear interaction of pile-soil is a meaningful and worthy research.Based on the soil-structure dynamics and vehicle-bridge coupling vibrationtheory, the simplified model of pile-soil-bridge-vehicle is built in this passage. Thevehicle-bridge coupling vibration considering nonlinear interaction of pile and soil isanalyzed and compared with the model ignoring the pile-soil interaction The mainresearch contents are as follows.1. Based on Beam on Winkler Foundation, modified P-Y curve method andload-transfer hyperbolic model are used to build the model of nonlinear pile-soilinteraction. The relative stiffness of the pile and soil is adopted to calculate thehorizontal initial stiffness of pile-soil interaction. The ultimate soil resistance isobtained by Mohr-Coulomb failure criterion. According to Matlock P-Y curvemethod, the expression of the ultimate soil resistance is improved, so the depth effectof the ultimate soil resistance is fully considered. The pile-soil nonlinear finite beamelement analysis program is compiled on the basis of these models.Thevehicle-bridge coupling model considering nonlinear pile-soil interaction is built Theinfluence of the main parameters of pile foundation on bearing capacity of the pilefoundation would be analyzed.2. Combined the vehicle model with four-axle rolling stock with two stagesuspensions and31degrees of freedom,the bridge which is regarded as spatial beamelement with12degrees of freedom and the pile-soil nonlinear interaction model, thepile–soil–bridge–vehicle model was build. To improve the computational efficiency, the―new explicit Newmark-β‖is adopted to solve the vehicle vibration differentialequations.―Newmark-β‖is adopted to solve the bridge(including pile) vibrationdifferential equations.3. The railway bridge is located in the deep soft ground, the finite element modelof which including the pile-soil nonlinear interaction is established. The vibration ofhigh speed railway bridge and the high-speed train are analyzed The displacementresponse of the bridge is larger while the acceleration response of the bridge is smaller.Pile-soil nonlinear interaction is good for the safety of the high-speed train Theseresults provide the parameters to the design of the high speed railway bridge locatedin soft ground with high-pile cap foundation.