Study On The Distribution Of Transverse Temperature Cracks In Ballastless Track Of High-speed Railway

With the development of railways in China,a large number of high-speed railways were conducted during these years,and the construction of high-speed railway has entered a new stage.However,rapid development of high-speed railway also brings problems and challenges at the same time.A certain degree of defects such as cracking?uplifting?warping of concrete base and track slab during the service in several high-speed rail lines caused by the lack of theoretical research on performance of ballastless track structure(BTS).It is very significant to conduct research on the defects of BTS which had a serious impact on the operation safety of high-speed railway.In this dissertation,theoretical analysis,numerical simulation,field test and disease investigation were carried out to analyze the failure modes of BTS Based on the CRTS II which used in Beijing-Shanghai High-speed Railway.The studies were the summary of previous results,and supported by the Funding of “Study on the design theory and method of whole life based on reliability of BTS”.Firstly,by means of finite analytic software ABAQUS,the slab ballstless track detailed models on soil subgrade and bridge which considered the material,load and boundary condition are established.Secondly,on the basis of the CRTS II slab ballastless track on soil subgrade and bridge,in accordance with the Fourier heat conduction equation and fundamental theory of heat transmission to study the law of temperature field distribution of BTS,and two types of suggestion values of temperature effect which influnence the temperature field of BTS are put forward.Again,based on the detailed model established in the previous paper,the stress and displacement of BTS under uniform cooling and temperature gradient are studied by using the basic theory of thermal stress.Subsequently,lateral cracking caused by uniform cooling was paid more attention based on a new calculation method.A cracking models considering the constraint effect of the reinforcement,lower support structure(CA mortar layer)and the bond between reinforcement and concrete was developed to analyze the formation mechanism and influence factor of BTS under uniform cooling.Eventually,in accordance with the analysis results,several design suggestion and maintenance measures are proposed to control the adverse effect caused by temperature load on the structure of CRTS II slab ballastless track.The results show that the temperature field of BTS is nonlinear,the shrinkage of concrete can be calculated by means of equivalent cooling,and we should put forward the temperature gradient recommended values which are suitable for the actual temperature and terrain in China.Cracking,middle arch and corner warping will appear under the action of uniform cooling,positive and negative gradient,and the preset cracks are the weak positions.The design parameters have a great influence on the distribution of cracks.We can control them in the stage of design,construction and maintenance of BTS.