基于热稳定性的冻土区铁路路基过渡段结构改进研究

Study on structural improvement of railway subgrade transition section in permafrost region based on thermal stability

自青藏铁路通车以来,其冻土地区铁路路基的融沉冻胀病害层出不穷,铁路路基过渡段的差异沉降问题尤为严重。基于一般地区铁路路基过渡段差异沉降的治理方法,结合冻土区铁路路基的主动降温措施,对冻土区铁路路基过渡段施工结构进行了探索性的改进研究,并对改进后铁路路基过渡段的长期热稳定性进行了分析。结果表明:将传统块碎石铁路路基上层路基填料换填成一定高度的单一粒径碎石,可使铁路路基在满足力学稳定性的前提下,实现最大限度的自然对流换热效应;通过数值模拟计算分析发现,改进后的铁路路基过渡段结构在气温变暖的环境背景下主动降温效果明显,且长期热稳定性好;桥台对铁路路基过渡段的温度场影响较大,建议对受太阳辐射强烈的桥台进行保温处理。

Since the Qinghai-Tibet Railway was brought into use,the problem of frost heaving and thaw which is on the permafrost railway subgrade has come out in an endless stream,and differential settlement of transition section on railway subgrade is particularly serious.This paper takes the exploratory improvement research on construction structure of railway subgrade transition section in the frozen soil area,at the same time,it takes the analysis of the long-term thermal stability of the transition section of improved railway subgrade.However the premise is that they are based on the governance method of differential settlement of railway subgrade transition section,and combined with active cooling measures of railway subgrade in frozen soil area.The results show that in the satisfying mechanical stability proposition,railway subgrade can achieve the maximum natural-convection heat transfer effect by replacing the filling of the upper layer of the subgrade named traditional block gravel with single particle size gravel for a certain height;Through numerical simulation and analysis,it is found that the structure of improved railway subgrade transition section under the environment of warmer temperature has obvious effect on active cooling,and the long-term thermal stability is well.The influence of abutment on the temperature field of railway subgrade transition section is great.It is suggested that the abutment which is strongly irradiated by the sun should be heat preservation treatment.