| The China Railway Track System Ⅱ(CRTS Ⅱ)slab-type ballastless track on bridge is a multi-layer slab system with longitudinal continuous and vertical anisotropy,which is widely used in high-speed railway lines in China.The common damage form is the crack of each structural layer and the debond of interface.The serviceable damage will affect the durability of the structure and the development of crack or debond may bring derivatives disease which will affect the safety of the track structure.There are many uncertainties in design,construction and operation of track structure,so it is necessary to analyze the reliability of track structure.The structural performance of the track structure is obviously affected by temperature.Therefore,the time-dependent reliability of serviceability limit state of of CRTS Ⅱ slab-type ballastless track on bridge during its 60-year service period was studied under different environment temperatures.The main work of this thesis is as follows:(1)The key parameters are identified and the different load effects in the track structure are analyzed.Firstly,the key random parameters that characterize material properties,component dimensions and load parameters are analyzed,and the corresponding probabilistic models are identified and established.Then,the load action of CRTS Ⅱ slab-type ballastless track in service process is analyzed one by one.In terms of train load,the effects of different forms of train load on CRTS Ⅱ slab-type ballastless track structure on bridge are analyzed;With the help of the ANSYS finite element analysis model,the bending moments generated by the vertical train load at different positions of the track structure are obtained,and the corresponding probability model is established;In terms of temperature,the effect of temperature on the track structure is analyzed;Using thermodynamic conduction formula,the probabilistic models of axial temperature and temperature gradient based on meteorological information are developed,and the correlation coefficient between these two temperature effects is considered;In terms of bridge deformation,the effect of bridge deformation on the CRTS Ⅱ slab-type ballastless track structure on bridge is analyzed.(2)The time-dependent reliability of various cracking failure modes of CRTS Ⅱtrack slab is studied.In view of the anti-crack failure modes at different transverse positions and pre-crack crack width over-limit failure mode of the track slab,the corresponding time-dependent limit state function is established,the loss model of transverse prestress and the calculation model of effective cross-sectional area of tensile reinforcement in track slab are selected by comparison;Considering that at different environment temperatures,the time-dependent reliability of single failure mode and system reliability of CRTS Ⅱ track slab on bridge during the 60-year service period are analyzed.(3)The time-dependent reliability of the debond of CA mortar/track slab on bridge is studied.The mechanism of debond between CA mortar and CRTS Ⅱ track slab is studied,the interface adhesion degradation model is proposed and compared,the time-dependent limit state function of the debond of CRTS Ⅱ CA mortar/track slab is established;Considering that at different environment temperatures,the time-dependent reliability of the debond of CA mortar/track slab of CRTS Ⅱ slab-type ballastless track on bridge during the 60-year service period is analyzed.(4)The time-dependent reliability of crack width of the foundation plate is studied.The limit state of crack width of the foundation plate is analyzed and identified,the calculation model of effective cross-sectional area of tensile reinforcement in foundation plate is selected considering corrosion of reinforcement,the limit state function of longitudinal crack width of the foundation plate is constructed;Considering that at different environment temperatures,the time-dependent reliability of crack width of the foundation plate of CRTS Ⅱ slab-type ballastless track on bridge during the 60-year service period is analyzed.The research results of this thesis will promote the development of the reliability research of the CRTS Ⅱ slab-type ballastless track on bridge,provide a basis for evaluating the service performance of the CRTS Ⅱ slab-type ballastless track on bridge. |
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