| It is clearly stated that the scale of China’s railway network shall reach 175,000 km in 2025 in the newly revised Medium and Long-Term Railway Network Plan,while the high-speed railway shall reach 38,000 km,especially,there is a great inclination to the western region under the background of the Belt and Road Initiative and construction of international channel and poverty alleviation.The railway construction in the western region ushers a new age,several passenger-dedicated lines are being built,which will play a vital role in releasing the capacity of the existing railway,giving full play to the transport efficiency of the existing railway and realizing the speed-up of the passenger and freight transportation in an all-round way.However,the existing routes in the western region are subject to the topographic conditions and the original capital investment.The design standards are relatively low,and the conditions for the transformation of large-scale line speeds are not available.How to make full use of existing line conditions,and to optimize the line parameters on a small scale to achieve the effect of speed increase worth further researching.The thesis mainly studies the function relationship between each evaluation index and parameters of railway line based on SIMPACK software package,which can provide an optimization scheme for the geometry parameters of future lines.The paper also makes a deep research into the train functioning under track irregularity conditions to explore the relationship between the train speed and track maintenance standards.The major contents are listed as follows:(1)Evaluation System of Track QualityThe thesis mainly studied the speed-up methods and quality evaluation contents of existing lines from both home and abroad,and the work was done from optimizing track geometric parameters and strengthening the structures both online and offline.A track evaluation system was then established,combined with the characteristics of the railway in western region,speed-up methods that can be adopted were also studied.(2)Construction of Vehicle-Track Integrated Model and Case Study based on SIMPACKA curve group with small radius in Lanzhou-Lianyungang Railway was taken as an example to build the Vehicle-Track Integrated Model,and the change of evaluation indexes such as the vertical force,lateral force,derailment coefficient and rate of wheel load reduction was calculated under different speed.And several line-upgrading schemes including various superelevation,radius,curve length were designed to study the influence that change of parameters have on evaluation indicators.(3)Relation Model of Evaluation Index and Geometric ParametersThe relationship between each parameter and evaluation index was studied according to the change of curve radius,actual superelevation and length of transition curves based on an upgrading scheme of a single curve.Function models between vertical force,lateral force,derailment coefficient and curve radius,length of transition curve,actual superelevation were established using ORIGIN software.(4)Speed-Raising Plan with Track IrregularityThe actual upgrading demand of Golmud-Lhasa railway was taken as an example to analyze the dynamic response under different track spectrums.The impact that linetype and length of transition curve have on train operation was simultaneously studied.An upgrading scheme was thus proposed for small-scale railway..(5)Research on Track Maintenance StandardTo obtain allowable irregularity that would affect security,the influence that track irregularity had on security was repeatedly simulated by adding specific value of single track irregularity at feature points.The difference was found compared with the existing maintenance standard,this can provide certain reference for the reliability evaluation on train safety and steady operation. |
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