Studies On Train-Track-Bridge Coupling Vibration Considing Soil-Pile Interaction

In recent years, Chinese high-speed railway has got a great development. With the operation mileage increasing and the vehicle operational speed accelerating, the vehicles, track and high-speed railway bridge's dynamic coupling interaction became more and more remarkable. Meanwhile, the large construction of the high-speed railway raise a higher demand for the bridges' danamic response, safety of the vehicle operation, comfortableness of passengers.The vehicle, track and bridge's dynamic models was established, using the vibration throry of them. The 4-axis-vehicle was Simplified as 7 rigid bodys, which have 35 drgree of freedom. The rail was Regarded as a Euler beam. the sleeper and ballast bed were cosidered as rigid bodys, then, dynamic equation of the vehicle and track coupling system was established. Using the finite element method and Hamilton variation principle, the bridge dynamic equation can be obtained. The vehicle-track-bridge system can be linked by the wheel-track contact relation and the bridge-track contact relation, therefore, a coupled dynamic model of train-track-bridge was built comparative completely. The vehicle-track system dynamic equation can be solved by the new explicit integration method. The Newmark-B implicit integration method can be applied to sovle the bridge dynamic equation.According to the loading mechanism of bridges' pile foundation, there used the bottom of pile cap's equivalent stiffness and Pile element-soil spring two methods to simulate the soil-pile interaction in this thesis. Taking a 60+2×100+60 m continuous beam of one double-track passenger dedicated line for example, bridge finite element models were built by using rigid connection in the bottom of pile cap, the bottom of pile cap's equivalent stiffness, pile element-soil spring 3 different processed methods of piled foundation stiffness. It's comparative analyzed for each bridge model's natural vibration characteristics and vehicle-track-bridge dynamic responses. At last it was primarily studied about the influence law on soil-pile parameters including pile foundation types, foundation pile space, size of pile diameter, m value of soil layer. It's concluded that it has a great effect on bridge's lateral responses if considing the soil-pile interaction. The design of pile foundation could be optimized by adjusting the foundation pile space and pile diameter size. The sensitive range of m value of soil layers was determined finally.