高速铁路路基与桥梁过渡段问题的研究精品.pptVIP

客运专线铁路路堤与横向结构物过渡段 * 3路堤与路堑连接处的过渡段 硬质岩石堤堑过渡方式 * 软质岩石或土质堤堑过渡方式 * 秦沈高速铁路涵洞过渡段动态试验 * * 动应力测试结果 * * * * * * * * * * 路基面应力增加，其它均减小 * * * * * * * * 四 Remedies at Track Transitions Over the past several decades a variety of measures have been developed by railroads for reducing the damage that takes place near transition points. They all aim at decreasing the vertical acceleration of the wheels and cars as the train moves through the transition zone. These remedies may be grouped in three categories: (I) The smoothing of the k-distribution on the soft track side of the transition (II) The smoothing of the transition by increasing the bending stiffness of the rail-tie structure on the soft track side, in the close vicinity of the transition point (III) The reduction of the vertical track stiffness on the hard side of the transition * 1) Longer Ties When considering Category (I), it appears that the most well-known remedy adopted by North American railroads is the one that uses progressively increasing wood-tie lengths in the track transition region (Fig. VIII.24). These longer ties create a gradual increase of the vertical track stiffness by engaging a larger section of the ballast. This method requires a sufficiently wide ballast section in the vicinity of the transition, unlike the one shown in Fig. VIII.25. Category I（增加轨道刚度） * Fig. VIII.24. Track transition remedies using ties of varying lengths * 2) Decreased Tie Spacing Another approach uses regular size ties throughout, but, in order to create the stiffening effect, the tie spacings are decreased gradually when approaching the stiffer structure. This method, used years ago, was phased out in recent decades after the introduction of mechanical tampers that work more efficiently when the tie spacing is constant. * Fig. VIII.25. Insufficient ballast section near bridge abutment * reinforcing layers utilize reinforcing geotextile layers, layers of Hot Mix Asphalt (HMA)