Safety Monitoring Of High Pier Highspeed Railway Bridge And Analysis Of The Train Running Performance

As an important infrastructure of high-speed railway system,bridge has the ability to cross complex terrain,which provides a good line condition for the comprehensive construction and safe operation of high-speed railway network in China.Among many bridge forms,the high pier bridge is more common in the area with complex terrain.It has the characteristics of large structure flexibility,difficult construction and high maintenance cost,and its structural deformation directly affects the train performance.Along with the high-speed railway gradually transforms from large-scale construction stage to operation and maintenance stage,the safety monitoring of high-pier bridges becomes an important task.Firstly,a train-track-bridge model is established by means of finite element and multi-body dynamics co-simulation method to study the influence of adverse deformation factors of high pier bridges on the running performance of high-speed trains.Secondly,the monitoring methods are designed for each adverse deformation factor,and several examples and working conditions are selected to verify the proposed monitoring methods.Finally,the proposed method is further extended and optimized.The main research contents and results are as follows:(1)Based on finite element method and multi-body dynamics,the coupling interaction model of train-track-high pier bridge is established.Firstly,the dynamical principles of three subsystems of vehicle,track and high pier bridge are discussed.The relationship between the subsystems is established through the wheel-rail relationship and the bridge-rail relationship.The time-domain samples of track irregularity are obtained by the inverse Fourier transform method,which are taken as the excitation input in the coupling system.Secondly,the finite element software is used to build the model of track and high pier bridge,the multi-body dynamics software is used to build the model of train,and the data transfer between the two software is realized through the flexible body interface.Finally,the reliability of the co-simulation method is verified.The results show that the proposed method has strong reliability and can be used to analyze and study the running performance of trains.(2)The influence of various deformation factors on the train running performance of high pier bridge is studied.The analysis is carried out around three kinds of deformation frequently occurring in high pier bridge: vertical displacement of pier top,beam deformation and lateral displacement of pier top.Taking the high pier high-speed railway bridge with three spans as the research object,the train running performance and the dynamic response of the bridge structure are extracted as the evaluation indexes.The results show that the vertical displacement of pier top and the beam deformation in the vertical plane mainly affect the vertical acceleration of the train.Pier top lateral displacement will cause the derailment coefficient,lateral acceleration and the wheel/rail lateral force numerical changes,among which the lateral acceleration of the train is the main influencing index.(3)Two monitoring methods for vertical in-plane deformation of high pier bridge are designed respectively for vertical displacement of pier top and beam deformation.Firstly,the mapping relationship between rail deformation and vertical displacement of pier top was deduced,and a method for indirectly monitoring vertical displacement of pier top through rail strain was raised.The reliability of the mapping relationship and the monitoring method were verified,and the application range and simplified form of the proposed monitoring method were further given.Then,combining the inclination monitoring theory and the least square method principle,the beam deformation monitoring method based on the inclination was established,and the deflection curve of the beam based on the polynomial function was given.The theoretical value of the deflection was compared with the measured value.The results show that the accuracy of the monitoring method is high.(4)A method for monitoring horizontal deformation of high pier bridge based on the pier strain is proposed.Firstly,the relationship between the strain and the lateral displacement of pier top was established based on the shape function formula,and the variation law of the monitoring error with parameters was studied through examples.The problem that the monitoring error was large when the slenderness ratio of pier is small was solved using the shear correction coefficient.The results show that the monitoring error of this method is small and does not change with the displacement amplitude and pier material parameters.Combined with reality,the effect of theoretical element division and pier height change on the monitoring method was studied,and the sensor layout scheme was further optimized under the two cases of equilength element division and non-equilength element division.The innovation of this paper lies in:(1)Based on the mapping relationship between rail deformation and vertical displacement of pier top,a monitoring method of vertical displacement of pier top of high pier bridge indirectly monitored by rail strain is constructed.The reliability of the method is verified by examples.Furthermore,the minimum monitoring range of the sensor and the simplified form of the analytical formula are given,which provides a new monitoring idea for the high-speed railway bridge which is difficult to lay out the reference point.(2)Based on the formula of strain and shape function,a monitoring method for lateral displacement of pier top was constructed,and the variation law of the method with parameters was studied.The problem of large monitoring error when the slenderness ratio of pier is small was solved by using the shear correction coefficient.Furthermore,an optimal sensor layout scheme was proposed.