Culverts and bridges are the most common areas on railway lines where abrupt changes of track stiffness can occur. Using auxiliary rails in the transition zone is one option for gradually increasing track stiffness. The study reported in this paper investigated this issue by means of finite-element modelling. A ballasted track with a concrete culvert on the Tehran–Isfahan high-speed railway line in Iran was modelled and the effect of installing auxiliary rails in the transition zone was investigated. The ballasted track and its components – including railpads, ballast and subgrade – were modelled as a series of mass–spring–damper systems, while the sleepers and culvert were simulated using Euler–Bernoulli beam elements. The dynamic behaviour of the track and its components was investigated by simulating loads moving at different speeds. The results indicated there was a reduced variation in rail deflections, track accelerations and railpad forces, demonstrating that auxiliary rails improve the dynamic performance and behaviour of transition zones.

中文翻译：

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辅助轨加固的铁路过渡带数值研究

涵洞和桥梁是铁路线上最常见的区域，可能会发生轨道刚度的突然变化。在过渡区域使用辅助轨道是逐渐增加轨道刚度的一种选择。本文报道的研究通过有限元建模研究了这个问题。对伊朗德黑兰-伊斯法罕高速铁路线上的带有混凝土涵洞的压载轨道进行了建模，并研究了在过渡区内安装辅助轨道的效果。道ast轨道及其组成部分（包括护垫，道ast和路基）被建模为一系列的质量-弹簧-阻尼器系统，而枕木和涵洞则使用欧拉-伯努利梁单元进行了模拟。通过模拟以不同速度移动的载荷，研究了轨道及其组件的动态行为。