Influence of Mortar Void Length Considering Random Mechanical Parameters on Running Performance
Research purposes:The mortar void disease of ballastless track directly affects the operating speed and running performance of high-speed railway line.Taking a six-span simply supported girder bridge-CRTS Ⅱ type ballastless track system and the CRH2C,CRH3 and CRH380A high-speed EMUs as the research object,the modal analysis of the ballastless track-bridge submodel is carried out based on ANSYS to obtain the overall mass,stiffness and damping matrix.Combined with HBMAT command and PYTHON language,the overall matrix is transformed into sparse matrix and imported into multi-body dynamics software together with node degree of freedom mapping file.Based on wheel-rail contact relationship,a dynamic model of track-bridge coupling system considering mortar void is finally established and verified.With the Chinese track spectrum as the initial irregularity,the track deformation caused by pier settlement based on the general representation model of bridge-rail developed by the author is the additional irregularity.Considering the randomness of fastener stiffness,mortar elastic modulus and pier settlement,the Box-Behnken method was used to design the test points based on Design-Expert software,coupled dynamics model calculation is carried out respectively to evaluate the running performance of CRH2C,CRH3 and CRH380A under different mortar void conditions and mechanical parameter randomness.Research conclusions:(1)The established dynamics model of train-track-simply-supported beam bridge coupling system is in good agreement with the calculation results of the literature model.(2)Under the same mortar void condition,the influence on the safety index is CRH380A＞CRH2C＞CRH380A,and the influence on the comfort index is CRH2C＞CRH3＞CRH380A,the influence on the stability index of the three types of trains is basically the same.(3)After considering the randomness of parameters,the index values of safety,comfort and stability indexes are all fluctuate up and down,and the control limits of each index are upper and lower limits boundary values.Taking the upper limit boundary value as the control limit is safer and more reliable than not considering parameter randomness.(4)The research results can provide some reference for the design and checking calculation of high-speed railway simply supported girder bridge.
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