路基的填料冻胀分类及防冻层设置

我国冻土区铁路路基表层的冻胀病害严重,且没有相应的路基填料冻胀性分类标准。在分析路基的冻胀特性、影响路基冻胀的因素、路基冻害整治中存在的问题的基础上,借鉴国内外地基土的冻胀性分类,并结合铁路路基填料分类的特点、铁路线路冻胀限高和维修标准,提出铁路路基填料冻胀性分类方案,并建议在冻土区设置路基防冻层。路基填料冻胀性分类方案以各类土的细粒含量、冻前含水量和冻胀高度为指标,进行冻胀敏感性和冻胀等级两级分类。路基防冻层应用细粒含量<5%的砂类和细粒含量<15%的砾类、碎石类不冻胀土填筑,防冻层的厚度根据路基的标准冻深。列车的运行速度和载重量确定。

Frost Heave Classification of Railway Subgrade Filling Material and the Design of Anti-Freezing Layer

There are serious frost heave diseases on the surface layer of railway subgrade in permafrost regions of China and there are no corresponding standards for frost heave classification of railway subgrade filling material in China.The characteristics of subgrade frost heave,the factors influencing subgrade frost heave,and the problems in the treatment of frost heave diseases are analyzed.On this basis,frost heave classification of railway subgrade filling material is presented and subgrade anti-freezing layer is suggested to be built in permafrost regions by borrowing domestic and foreign ideas of frost heave classifications for foundation soil,according to the characteristics of railway subgrade filling material classification,the limit depth of frost heave and the criterion of maintenance for railway track.The new frost heave classification for subgrade filling material is divided into two levels,which are frost heave sensitivity and frost heave rate,according to such indexes as fine granule contents of soil,pre-freeze water content in soil and frost heave depth.Non-frost-heave soil such as sand with fine granule content less than 5%,gravel with fine granule content less than 15% and crushed rock can be used to build the anti-freezing layer of subgrade.The thickness of the anti-freezing layer will be decided by the standard frost depth of subgrade,the running speed and the loading capacity of train.