Theory And Application Of Vehicle-Turnout-Bridge Coupling Vibration In High Speed Railway

High speed railway is characterized by more viaducts and long bridges than existing railway line, and throat area of railway station is more possible to be set on a bridge, because there are strict requirements for regularity of high speed railway. High speed railway turnout as a key speed-limit equipment is set on bridge, and it results in violent dynamic interaction between turnout and bridge structure, so the safety and comfort of a train passing a turnout on bridge are decreased. With the construction of Passenger Dedicated Lines (PDLs) and high speed railway in China, it is one of basic issues to study the dynamic interactions between vehicle and turnout on bridge under the high speed running condition. According to the reference research data of vehicle-bridge vibration theory and turnout dynamics at home and abroad, vehicle, track of turnout zone and bridge are viewed as an integrated system. Based on vehicle dynamics, turnout dynamics and bridge finite element method, with wheel/rail relation and turnout/bridge relation as connection links, a numerical simulation method is applied to study the dynamic characteristics of track in turnout zone and bridge structure, running safety and comfort under high speed running condition, so as to provide theoretical support for design scheme estimation and parameter optimization of welded turnout on bridge of high speed railway. Main research works are as follows:(1) Vehicle-turnout-bridge coupling vibration system modelA vehicle is viewed as a 7 rigid-body (1 car-body,2 bogies, and 4 wheel-sets) vibration system connected by suspension spring and damper. Each rigid-body has 5 degrees of freedom (DOFs), i.e. yaw, pitch, rolling, shaking and vertical vibration, and total DOFs of the whole vehicle amounts to 35. A complete turnout dynamic model, which contains switch proper, linking parts and frog, is established by integrating structure characteristics of high-speed turnout. Such factors as rail section variation, jacking block contact force, spacer block high strength connection, and sliding platform nonlinear support are also taken into account. Sleeper or support block are viewed as a rigid-body which considers its vertical, transverse and rotation DOFs; vertical vibration of ballastless track slab is considered as an equi-thickness rectangular thin plate on elastic subgrade, while its transverse vibration is viewed as rigid-body movement. Dynamic finite element method is applied to the discretization of bridge structure.(2) Dynamic interaction principle, coupling vibration analysis theory and corresponding all-purpose program DATTBWith comprehensive application of following theories, such as wheel/turnout multi-point dynamic contact relation, wheel/rail Hertz nonlinear contact theory, wheel/rail creep theory, turnout/bridge interaction, the principle of vehicle-turnout-bridge dynamic interaction is discussed in detail. Viewing high speed turnout structure and state irregularity as main excitation, a vehicle-turnout-bridge coupling vibration analysis theory is established by using Hamilton Variation Principle and'Numbered Seat Principle'. Related dynamics simulation all-purpose program DATTB is completed.(3) Analysis on evaluation standard for high speed turnout/bridge structure application safety and running comfortThe safety and stationarity when train passing turnout on bridge, strength and stability of turnout and bridge are viewed as the dynamic evaluation guide line of turnout on bridge. Dynamic performance evaluation indexes of vehicle-turnout-bridge at home and abroad are all concluded, i.e. wheel/rail vertical and transverse force, wheel axle transverse force, opening of switch and nose rail, dynamic stress of switch and nose rail, derailment coefficient, rate of wheel load reduction, car-body vibration acceleration, ride index, bridge deflection, bridge natural frequency, bridge transverse amplitude and bridge vibration acceleration.(4) Experimental study on Vehicle-turnout-bridge coupling vibrationAiming at 200km/h speed 60kg/m rail 12# ballasted turnout on Meichi large bridge of Zhe-Gan line, dynamics assessment is explored by applying DATTB, whose reliability is testified through comparison between simulation results and experimental results. Meanwhile, comparison analysis of dynamic tests between turnout on bridge and turnout on subgrade shows that wheel/rail dynamic interaction of turnout zone on bridge is more violent than that of ordinary turnout on subgrade.(5) Research on laws of dynamic interaction between high speed vehicle and turnout on bridgeBy studying influences of variable factors on vehicle-turnout-bridge coupling system, the laws of dynamic interaction between high speed vehicle and turnout on bridge are revealed and guide principle for dynamic design of welded turnout on bridge of high speed railway is suggested. Optimized wheel/rail relation of turnout zone and track stiffness, reasonable bridge vertical flexural stiffness and ideal relative position between turnout and bridge are the keys to maintain the safety and comfort of high speed train passing turnouts on bridge.(6) Engineering application of vehicle-turnout-bridge coupling vibration theoryPractical application of vehicle-turnout-bridge coupling vibration theory is discussed on the basis of dynamics evaluations of 350km/h 18# ballastless turnout (French COGIFER) on multi-collocation continuous beam bridges of Zhengzhou-Sian PDL and 250km/h 30# ballasted turnout (China Independent R & D) on (48+2×80+88+48) m continuous beam bridge of Xiamen-Shenzhen mixed passenger and freight railway line.