研究结论:分析结果表明，混凝土的收缩、徐变以及桥梁刚度偏弱是产生桥上周期性高低不平顺的主要原因。此外，桥上的 32 m 波长周期性不平顺恰好落在 160 km/h 和 200 km/h 下列车的敏感波长范围内。相同幅值时，200 km/h 时垂向加速度响应最大，160 km/h 时减载率响应最大，并且高低不平顺幅值为 7 mm 时垂向加速度已超过 0． 15g，即超过了垂向加速度Ⅱ级舒适度指标，应当对桥上轨道不平顺进行整治。
Abstract：Research purposes: Since the Chengdu － Dujiangyan Intercity Railway was open to traffic，the periodic track irregularities on the bridge have been found by many inspections of the track dynamic profile． In order to dynamically know the impact of the periodic track irregularities on the safety and comfortableness of EMU，this paper analyzes the cause for the irregularities and development law of the irregularities with the statistical methods and dynamics simulation technology．
Research conclusions: The analysis results show that the periodic track irregularities on the bridge may be mainly caused by the concrete ＇s shrinkage and creep or the low stiffness of bridges． In addition，the irregularity of the 32 m －wavelength on the bridges is exactly in the ranges of sensitive wavelength of the trains at the speeds of 160 km / h and 200 km / h． Under the same amplitudes，the maximum vertical acceleration response is got at the speed of 200 km / h and the maximum unloading rate response is acqured at the speed of 160 km / h，and when the amplitude reaches at 7 mm，the vertical acceleration is over 0． 15 g，which exceeds comfortableness index Ⅱ． So it is necessary to treat the track irregularity on the bridge．
Lian Songliang，Huang Junfei． Study of the Detrimental Wavelengths of Track Irregularities for Railway with Passengers and Freight Track［J］． Journal of the China Railway Society，2004( 2) : 111 － 115．
Fang Jian， Lei Xiaoyan，etc． Research on Track Irregularity and Unfavorable Wavelength of Speed － increased Railway［J］． Journal of Railway Engineering Society，2010，146( 11) : 28 － 31．
［6］ 铁运［2006］146 号，铁路线路维修规则［S］．
Railway Transport ［2006］ No． 146，Railway Track Maintenance Rules［S］．
Liu Jiafeng，Liu Chunyan． A Summary of Bridges on Qin － Shen Passenger Dedicated Railway and Pondering over Bridge Construction for High － speed Railway［J］． Railway Standard Design，2004( 7) :134-137.
2011, Vol. 28 
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