The Optimize Structure Design Of CRTSⅢ Slab Ballastless Track For Mixed Passenger And Freight Railway

In order to meet the increasing traffic pressure or emergency transportation(combat transport,disaster supplies transport),and continue to promote the CRTS III slab ballastless track to overseas(the strategic conception of "High-speed rail to overseas"and"The Belt and Road Initiative"),the large axle load trains will also be able to operate on the ballastless track daily.The Passenger/freight vehicle(the difference of running speed and axle load is larger)running on the ballastless track alternately,so the bearing capacity of the track structure system changes frequently.It has adverse effect on the function and service life of track structure,and puts forward higher requirements for the safety,durability and smoothness of ballastless track.Therefore,it is necessary to optimize the design of CRTS III slab ballastless track of the mixed passenger and freight railway.The main contents of this paper are as follows:(1)Study on stiffness matching of CRTS Ⅲ slab ballastless track of the mixed passenger and freight railwayThe quasi-static and dynamic response analysis methods are used to analyze and discuss the component stiffness and whole stiffness of CRTS Ⅲ slab ballastless track.Under the condition of different stiffness matching,the internal force and dynamic response of track structure are analyzed.By introducing the sensitivity coefficient of the dynamic parameters,the dynamic parameters of the track structure are calculated quantitatively,and the sensitivity of the dynamic coefficients to the stiffness of the components is determined.Under the condition of mixed passenger and freight lines,the optimal matching scheme of track stiffness is determined by establishing the function of the minimum response of the sensitivity coefficient.(2)Study on reinforcement of track structure based on limit state methodStudy on the reinforcement of CRTS Ⅲ slab ballastless track slab and self compacting concrete layer under combined design load.And the reinforcement ratio,the height of compression zone,the stress of steel bar,the stress of concrete,the crack resistance and the bearing capacity of the slab are examined.(3)Study on the structure of CRTS Ⅲ ballastless track of mixed passenger and freight railway on special sectionThe design of track structure in turnout area is studied,and the reasonable transition scheme of track structure stiffness on bridge-subgrade transition section is discussed.The results show that for CRTS Ⅲ slab ballastless track of the mixed passenger and freight railway,it is suggested that under the condition of train load,the track deformation should be controlled within 1.5mm,and the overall stiffness of the track is 110kN/mm,and the pivot stiffness of the rail is 45kN/mm.Based on the minimum comprehensive characteristics of the dynamic response of the track to establish function,the optimal stiffness of CRTS Ⅲ ballastless track of mixed passenger and freight railway is determined,which is 50kN/mm of the fastener stiffness and the stiffness of the cushion surface 600MPa/m.The CRTS Ⅲ ballastless track of bridge-subgrade transition section can be used to reduce the vertical stiffness of the bridge(gradually changing the stiffness of the buffer layer);the first cushion surface stiffness of 225MPa/m,divided into five plates gradually transition to the surface stiffness of 600MPa/m.