基底条件对重载铁路隧底结构动力响应的影响及服役寿命分析

Analysis of the Influence of Basis Conditions on the Dynamic Response of a Bottom Structure of a Heavy Haul Railway Tunnel and Its Service Life

铁路隧道在长期运营条件下易产生基底软化和脱空现象,对隧道结构的服役寿命影响明显。文章通过一系列不同频率正弦函数的叠加表征列车振动荷载,并考虑隧底结构与基底围岩之间的相互作用,建立了隧道-围岩的数值模型,探讨了基底条件改变对隧底结构的动力响应特性的影响规律。然后基于Miner线性累积损伤理论,分析了基底状况对重载铁路隧道服役寿命的影响情况。计算结果表明:不同软化及脱空条件下,隧道底部结构动应力响应规律相似,隧底结构各部位平均应力和应力增幅值增大,疲劳寿命缩减。隧底结构仰拱中心处出现拉应力最大值,隧道轨下仰拱首先出现疲劳破坏。

Bottom softening and voids in a railway tunnel often occur over long-term operation, which has a great impact on the service life of the tunnel structure. Based on the train vibration load represented by the superposition of sine functions with different frequencies, a numerical model is established of a tunnel rock mass with consider- ation given to the interactions between the tunnel bottom structure and foundation rock mass. The influence law is discussed based on the changing characteristics of the dynamic response of the tunnel bottom structure, and the in- fluence of the basis condition on the service life of the heavy haul railway tunnel is analyzed based on the Miner lin- ear cumulative damage law. The results show that in different softening and void conditions, the dynamic stress re- sponse regularities of the tunnel bottom structures are similar; average stress and stress amplification on each part of the tunnel bottom structure increases, and its fatigue life decreases; the maximum value of tensile stress occurs at the center of the invert at the tunnel bottom; and fatigue failure first occurs at the invert under the tunnel track.