Deformation Of Medium Speed Maglev Guideway Under Sunshine Temperature And Its Effect On Coupled Vibration

Medium-speed maglev traffic has many remarkable advantages,such as low noise,small vibration,safety and comfort,strong climbing ability,small turning radius,flexible route selection and small footprint.It has broad application prospects.At present,there is no engineering example of medium-speed maglev with a speed of about 200 km/h in China and lacking of corresponding codes.Choosing a reasonable structure of guideway is an important guarantee for the safety and economy of maglev system.Deflection-span ratio and fundamental frequency are two key control parameters of guideways.The limit values of deflection-span ratio and fundamental frequency of guideways in different national codes were summarized in this paper.It is determined that the limit value of the deflection of the guideway with span L should be less than L/3800 under the static load of the vehicle and the fundamental frequency should be greater than 90/L.Based on the limitations above and combined with the comprehensive economic evaluation,the structure forms of single-line and double-line maglev guideway with span of 25 m are designed out.Temperature difference leads to deformation of guideway,which is an important factor affecting driving safety and comfort.The existing specifications for the temperature gradient of guideway is based on single-room box girder.It is not clear whether the temperature distribution of double-room box girder is similar to that of double-track box girders and whether it can be directly used in design.Based on the theory of heat transfer and the meteorological parameters of summer temperature in Shanghai,the temperature changes of two guideways in one day are analyzed by ANSYS.The most unfavorable temperature gradient curve and the deformation of guideway under temperature gradient are obtained.The results show that the temperature gradient is inconsistent with the mode in the code,the deformation of the guideway under the temperature gradient in the code is larger.In order to study the influence of coupled vibration between maglev train and guideway with temperature deformation,the vibration response of train and guideway with or without temperature difference is compared by using MATHEMATICA program.It is found that the temperature difference enlarges the vibration of the guideway when the speed of maglev train is within 180 km/h,when the speed increases,the influence is not obvious.Within design speed,all indicators of coupled vibration response of train and guideway can meet the relevant standards and requirements.