Optimization Design Of Ordinary Reinforced Concrete CRTSⅢ Slab Ballastless Track Structure

The slab ballastless track is one of the main track structure types of high-speed railways in China.It has the advantages of high smoothness,high stability and low maintenance.It has been widely used.In view of a series of problems in the operation of existing slab slab track lines,China has independently developed CRTSⅢ slab track.This structure was first used in Chengdu to the Dujiangyan Railway in 2010.It was in good condition and was subsequently promoted to the high-speed railway lines of Wuhan City Circle,Shenyang to Dandong,Zhengzhou to Xuzhou.In order to further reduce the cost,improve the economics of the CRTSⅢ slab track technology,and study the adaptability of the CRTSⅢ slab track ordinary reinforced concrete track plate,a test section was laid in a part of the Chengdu-Guiyang passenger line.At present,in the process of designing the reinforcement of the track structure,the track plate itself is usually considered as the whole force.However,in practice,the precast track plate and the cast-in-place self-compacting concrete layer are connected into a composite plate structure through the door-type steel bar,realizing the synergistic force.Therefore,it is necessary to carry out the reinforcement design according to the composite plate structure in the design.In this paper,the CRTSⅢ slab track test section of the ordinary reinforced concrete track plate laid in Chengdu-Guiyang Passenger Dedicated Line is used as the background,and the static model of the slab track is established.The load value is determined and the force characteristics of the composite plate structure are analyzed.The load was designed based on the limit state method,the bending moment of the composite plate design was determined,and the overall reinforcement design was carried out.Considering the temporary bending moment load of the track plate during manufacturing,transportation and construction,the lower layer reinforcement of the track plate is designed.The main research contents are as follows:(1)The static calculation model of CRTSⅢ slab track on the subgrade is established.The static characteristics of the composite plate structure under temperature gradient,train vertical load,overall lifting temperature and combined load are analyzed,and the weak parts of the composite plate structure are determined.(2)Based on the limit state method,the load values of train load,temperature gradient and foundation deformation are determined.According to the design load combination principle,the overall reinforcement design of the track plate and self-compact concrete composite plate structure is carried out,and checked the tensile stress of the steel bar,concrete compressive stress and crack width;Consider the temporary load of the prefabricated track plate during the manufacturing process,and complete the reinforcement design of the lower layer of the track plate.The research shows that the weak part of the track plate and self-compacting concrete composite plate structure is self-compacting concrete layer;the longitudinal positive bending moment of the composite plate structure design on the subgrade is 44.73kN·m/m,and the longitudinal negative bending moment is 18.68 kN·m/m.The lateral positive bending moment is 24.82kN·m/m,and the lateral negative bending moment is 20.00 kN·m/m;the bending moment of each direction on the bridge is smaller than that of the subgrade;Under the temporary load,the longitudinal bending moment of the lower surface of the track plate is 22.1kN·m,the transverse bending moment is 42.69kN·m,the longitudinal bending moment of the surface of the track plate is 21.5 kN·m,and the transverse bending moment is 33.2kN·m;The control index of the reinforcement design of each layer of the composite board is the minimum reinforcement ratio;Through the comparison of the reinforcement amount,it is proved that the composite plate reinforcement based on the limit state method can reduce the total length of the track plate steel bar by 22.8% compared with the existing track plate,and the total length of the steel bar in the self-compacting concrete is reduced by 0.38%.