寒区高铁路桥过渡段冻结特征及热影响区域数值分析

Numerical analysis on freezing characteristics and thermal influence areas of roadbed-bridge transition section of high-speed railway in cold region

随着我国高速铁路网络逐步向寒区大范围延伸,线路纵向上选用了较高比例的桥梁以跨越地形,势必出现大量的路桥过渡段。路桥过渡段使线路纵向上出现了刚度变化以及桥用、路用材料的工程抗冻性能差异,进而引发不均匀的冻胀和融沉变形,产生桥头跳车的可能,降低行车的舒适度和安全性。文章运用土壤冻融条件下热传导理论的基本方程和数值方法,结合哈大高铁的典型工况建立路桥过渡段模型,计算分析其在春季融化期间的冻结特征差异和演变规律,并基于工程优化设计了三种不同的台后填筑模式,得到冻融条件下该气候分区的热影响范围,并基于此分析了冻结圈面积、周长、长宽比和横向热扰动距离等几何指标。计算结果表明,仅考虑热学影响时,在有保温层和无锥台护坡工况下,路桥过渡段的综合效果较好。

With the gradual development of high-speed railway in cold region,a large proportion of bridges were used to cross the complex terrain and roadbed-bridge transition sections were appeared.For the discontinuities changes of stiffness between bridge and roadbed,and the anti-frost properties difference of geomaterials,the uneven frost heave could be triggered and reduce the comfort and safety of the vehicle.In this paper,the equations of heat transfer about soil freezing and thawing were considered to analyze the freezing characteristics and changing process,with the parameters of model which derived from Harbin-Dalian high-speed railway.Then in the optimal design stage,three different models were analyzed for the four parameters of frozen area,perimeter,ratio of length and width,and transverse thermal disturbance distance.The results show that the model of insulation layer and non-cone slope provides a better effect for the roadbed-bridge transition section,as just considering thermal influence.