Research On Mechanical Characteristics And Monitoring Scheme Of Subway Turnout Under Complex Operating Conditions

With the seamless development of the urban rail transit and the trend expansion of transport range, more and more subway turnouts are set on the ground lines and elevated stations, bearing the load of temperature, train and bridges. The coupling of multiple loads cause some turnout disease, such as rupture of rail, crawling, fastener resistance change, etc. In addition, consolidation settlement of stratum, construction of crossing Engineering, and settlement of bridge pier will also affect the state of track structure, change the track geometry, and endanger the operation security., This paper research on monitoring scheme based on mechanical characteristics analysis of turnout structure. A new evaluation standard of schema optimizatio based on the best curve fitting was proposed, and a new technology is adopted to explore long-term real time monitoring. The main works and conclusions are shown as follows.(1)Based on analysis of the structural parameter, the spatial refinement coupling model of subway single turnout and crossover turnout is established by using the finite element software ANSYS with considering the influence of substructure, such as tunnel, soil, bridge on mechanical characteristic of turnout. A rigid-flexible coupling vehicle-turnout-monolithic track bed model was established by using multi-body dynamics software SIMPACK.(2)Statics sensitive areas including stress sensitive area, deformation sensitive areaand working condition sensitive area, corresponding to the areas of space block on turnout basic rail, tip region of point rail, beam end, and transition region where temperature changing from high to low. Statics sensitive indexes including longitudinal force, longitudinal displacement of rail, rail temperature, air temperature, deformation of bridge, etc. Switch area, frog and middle part of the guiding curve are identified as dynamical sensitive region. And the corresponding sensitive indexes are lateral and vertical wheel-rail force, lateral and vertical displacement of rail.(3)Measuring point selection for statics long-term monitoring and a new evaluation standard are proposedbased on evaluation method of the best curve fitting. This paper also summarized evaluation standard of track structure dynamic, and research on the selection of dynamic monitoring points and monitoring scheme.(4)This paper analyzed mechanical properties of metro turnout system under conditions of rail rupture, fasteners resistance change, vertical displacement of monolithic track bed, and settlement of piers based on finite element model. A healthy monitoring scheme is proposed based on dense arrangement of measuring points for rail longitudinal force.(5)Combined with the fiber grating,4G wireless network technology, mobile video monitoring technology and computer technology,the long-term monitoring data management information system for metro turnout was preliminarily studied. The research of metro turnout warning, analysis of alarm threshold and data forecasting method are also carried out.This paper combined with static and dynamic analysis results and fiber grating technology, the long-term monitoring system of metro turnout has been set up. Measurement point selection criteria and program optimization evaluation system has been formed. The stress and deformation law of metro turnout under typical damages has been studied. The function of data storage, analysis, prediction and alarm is preliminarily explored.