Research On Subway-Building Combined Structure System Coupling Dynamicsand Vibration Control

As the urban rail transit develops continuously, due to the urban planning, subway line design and building land limitations, the subway line has to cross the building land under special circumstances, which forms the subway-building combined structure system. The appearance of subway-building combined structure system provides a good way of solving the contradictory of urban land use planning and subway land use planning and saving the land resource. However, in this combined structure, the subway line has no choice but get through the buildings with elevated bridges or directly be laid on the floors of the buildings, thus the vibration problem brought along becomes worse. For the subway-building combined structure system itself, the subway and the building nearby interact with each other and get influenced by each other when the subway vehicle runs, which forms a spatial coupling dynamic system. In order to simulate the dynamic behavior of the system when the vehicle passes, a spatial coupling dynamic model should be established which is comprised of vehicle, track, foundation, building and the interactions between each structure. Thus, a vehicle-track-foundation-building spatial coupling dynamic analytical method has been established in this thesis. The detailed mechanical characteristics of the vehicle, track, foundation and the building sub-model has been simulated, and the spatial coupling dynamics analysis has been accomplished through the connections and interactions between each sub-models. Based on this analytical method, the spatial vibration characteristics of the subway-building combined structure system with two combined structure types named "subway building separately built" and "subway building combined built" have been analyzed, and the vibration control technologies for each combined structure type have been proposed. Finally, taking a real case of the vibration mitigation design of subway-building combined structure at Maquanying car depot, the comprehensive evaluation index set has been established. The system dynamic behavior of the subway-building combined structure at Maquanying car depot with ballasted track and steel spring floating slab track has been evaluated. The main research contents are as follows:(1) Subway vehicle-track-foundation-building spatial coupling dynamic simulation platform was established.Based on the Multibody dynamics(MBS), Finite Element Method(FEM), contact dynamics, wheel-rail interaction theoryand structural dynamics, the modelling theory, of the vehicle sub-model, track sub-model, foundation sub-model, and the building sub-model have been studied. Through the wheel-rail interactions and interactions between each sub-model, the vehicle-track-foundation-building spatial coupling dynamic simulation platform VTFBSIM was established. The validity of the platform has been verified against field test results. Comparisons between the simulated results and test results showed good agreements with each other, which proves the validity of the platform.(2) The dynamic behavior of the subway-building combined structure were analyzed.The dynamic behavior of the vibration source and the building when the vehicle passes were analyzed in both time domain and frequency domain for the "subway building separately built" and "subway building combined built". The influencing law of the vehicle running situations, the height of the building and the location where the subway line runs through the building were studied.(3) The comprehensive vibration control technologies for "subway building separately built" were studied.The vibration characteristics of each floor of the building with different track structures were studied, and the variations of the building vibrations were compared with different track structures. The vibrations of the building with vibration mitigation bearings and normal bearings were studied, the influencing laws of the mechanical parameters of the vibration mitigation bearings were analyzed.(4) The dynamic behavior of the "subway building combined built" was analyzed, and the comprehensive vibration control technologies were studied.Based on the vibration isolation theory, two types of floating floor have been proposed:the continuously supported floating floor and discretely supported floating floor. The vibration mitigation tracks and the floating floor have been treated as one order vibration isolation system each. First, the dynamic behavior of the "subway building combined built" system was analyzed with first-order vibration isolation system. The vibration mitigation effects were compared between vibration mitigation tracks and floating floor. Then the dynamic behavior of the "subway building combined built" system was analyzed with second-order vibration isolation system. The influence of vibration mitigation tracks and floating floor types were compared. Finally, the comprehensive vibration control technologies for "subway building combined built" system were proposed through the comparisons between the first-order and second-order vibration isolation system.(5) A case study for subway-building combined structure was carried out.The comprehensive evaluation index set for the subway-building combined structure was established taking into consideration of the vehicle running safety and smoothness, structure fatigue damage, in-door vibration and human exposure to vibration. Based on this index set, the system dynamic behavior of the subway-building combined structure at Maquanying car depot with ballasted track and steel spring floating slab track has been evaluated with the vehicle-track-foundation-building model. By the comparisons of the results and the limits from the standards, it shows with the ballasted track, every indexes go under the limits with certain margin except the vibration of B2 exceeds the vibration limits for the night-time.