Study On Coupling Dynamic Behavior Of Metro Vehicles And Track Of Steel Spring Floating Slab

China is making great efforts to develop the urban rail transits to ease traffic congestion for large and medium-sized cities. The vibration, noise and environmental issues caused by urban rail traffics are increasingly of concern. A variety of noise and vibration reduction measures have been used to weaken the impact of urban rail transit lines along the residents, constructions and precision instruments. At present, compared with other noise and vibration reduction measures used in urban rail transits, the overall performance of steel spring floating slab track is the best, it was gradually used in the demanding locations in the vibration control. With China’s quick economic development and the awareness increase of the health of residents, steel spring floating slabs will be widely applied to the new urban rail transit lines.Steel spring floating slab track has many advantages, such as the damping effect and the inertial vibration reduction, convenient maintenance, long life and so on. However, the high initial investment, complex construction, long duration, and poor stability severely restrict the scope of its use. Scholars at home and abroad adopted various methods to analyze the performance of floating slab track. For continuous floating slab tracks, the concerned study focuses on the vertical resonant frequency of the track, the critical velocity of the floating slab tracks and orbital calculation of compliance and damping efficiency. For the discrete floating slab track, the study focuses on the bending flexible deformation with damping, the vertical dislocation of slabs at the joints, connecting transition between floating slab track and others.Many research results on the floating slab techniques and its application have been obtained and some problems of the floating slab tracks were solved. But many questions are still open. So far people have not carried out the detailed investigations into more new types of structures and techniques applied to the floating slab tracks and not yet optimized the floating slab track structure further. The concerned important problems include the safety operation of the metro trains in the partial and total failure of the track parts, the hinge joint use at the connection of two slabs improving the dynamical behavior of the vehicle and the track, improvement on the transition section between a general slab track and a floating slab track, and the floating slab track matching a metro train of linear induction motor. Aiming at the problems the present work conducts the following researches:(1) First the thesis gives a detailed discussion on the history and current status of study and application of the floating slab track at home and abroad, and describes the significance and direction of development and application of steel spring floating slab tracks.(2) Thesis carries forward further the coupling dynamics model of a metro train and a floating slab track and the corresponding numerical code. The mian innovation work includes that (a) the coupling dynamic model for a linear induction motor metro train and a floating slab track and its numerical code is developed,(b) the dynamic models considers the constant speed motion of the tracks with respect to the trains,(c) the model for the foating slab track considers the modeling of the hinged joints between the slabs and the behavior analysis,(d) the finite element method is used to simulate the floating slabs, which considers the optimization of the sizes of the slabs, calculate the more reliable results and the failure status of the track parts or in the location of the parts, and (e) the modes are used to analyze the effect of the track support stiffness in the transit section between the general slab track and the floating slab track on the dynamic behavior of the vehicle and the track and the effect of the uneven support stiffness of the tracks.(3) The effect of the sizes of the floating slab and the space between the springs supporting the slab on the dynamic behavior of the vehicle and the track is analyzed when the general metro train (electric rotating motor driving) is operating on a floating slab track. The considered sizes include the height and length of the floating slab. The mechanism is understood redarding the effect of the characterestics of the floating slab track on the dynamic behavior of the vehicle and the track. The research results show that the change of the parameters of the floating slab track does not have a great influence on the vibration acceleration of the vehicle and the track. The operation of metro trains on the floating slab track is very safely.(4) The thesis calculates the effect of the vertical dislocation between the ends of the two floating slobs on the dynamic behavior of the vehicle and the track when the general metro train (electric rotating motor driving) is operating on a floating slab track. The calculation results show that the influence of the dislocation on the wheel/rail forces is very small, but is great on the forces in the fastenings at the gap of the two slabs. Using the hinged joint in the connection of the slabs can effectively reduce the influence caused by the dislocation on the forces in the fastening, the fastenning illness and the maintaining cost.(5) The present work calculates the effect of the support stiffness change of the transition section between the general slab track and the floating slab track on the wheel/rail forces, the forces in the fastening and the deformation of the track. The calculated results indicate that the sudden change of the support stiffness of the transition section does not have a great influence on the wheel/rail force, but has a great influence on the forces in the fastening systems in the transition section. Hence the transition section needs to use the slow change of the support stiffness which effectively reduces the compression and tension of the fastenings in the transition section. The other measures to reduce the forces in the fastening systems are, respectively, using the hinged joints in connect the floating slabs, increasing the distribution density of the support springs and decreasing the stiffness of the fastennings.(6) The effect of the failure of the springs or of the fasteners on the track defoemation and the operation safety of the train is analzed. The results show that the operation safety of the train is serious influenced only when the number of fastener continuous failure to a certain extent. The failure of only a few springs has a small influence on the safe operation of the train, but has a great influence on the deformation and the displacement of the slab and the forces in the fastening.(7) Using the present model analyzes the dynamic behavior of the linear motor vehicle operating on a steel spring floating slab track. It is clear that the effect of the gap of the slabs relative to the gap of the reactor plates on the dynamic behavior of the system. The effect of the vertical dislocation of the reactor plates on the force state in the system is analyzed and understood clearly. The research results indicate that the gap of the floating slabs should align at the gap of the reactor plates in the construction of the track. In maintaining the tracks the dislocation of the reactor plates should be strictly controlled.(8) Based on the field experiment data, the thesis analyzes the floating slab track service status and the effect of the rail status of a floating slab track on the vibration of the vehicles. Compared to the tracks with the other vibration reduction measures, the field experiment datum show that the floating slab track has more advantages in the vibration reduction.