改良粗颗粒填料在寒区高速铁路路基中的应用研究

高速铁路路基填料选用传统意义上平均冻胀率η≤1%且级配良好的非冻胀填料,目前高速铁路路基在寒季产生的实际冻胀量已超过规范规定15 mm的要求。针对寒区高速铁路路基冻胀问题,从填料改良方面开展研究,针对路基产生冻胀的主要位置,选取级配碎石为对象,以水泥、石灰、粉煤灰作为掺和料进行改良。通过室内试验,分析加入无机材料后填料渗透性和冻胀性的变化,对比加入3种掺和料的填料冻胀率,选取一种改良效果最为理想的材料,作为寒区高速铁路路基改良材料。研究结果表明:水泥、石灰以及粉煤灰的加入大幅度减少了水分从路基表面向基床内部的渗透,其中粉煤灰吸水能力较强,因此产生了较大的冻胀量,不适宜作为改良材料;水泥改良填料冻结时水分迁移量减少,冻胀量最小,说明相对石灰和粉煤灰,水泥最适合加入到级配碎石中,减小路基冻胀量。

Application Research on Improved Coarse Grain Filling Material for High Speed Railway Subgrade in Cold Regions

The traditional well graded filling material with average frost heaving ratio η≤1% is used in the high speed railway subgrade,and the actual frost heaving value has exceeds the requirements for high speed railway subgrade of less than 15 mm. The paper aims focuses on the frost heaving of high speed railway subgrade in cold regions and the improved subgrade filling materials. The graded gravel mixed with cement,lime and fly ash is selected based on the main frost heaving location of subgrade. Through indoor experiments, the change of permeability and frost heaving properties after adding inorganic materials are analyzed and the frost heaving ratios with three admixtures are compared. Thus,the material with best improved effect is selected as the improved material for high speed railway subgrade in cold regions. The research results show that cement,lime and fly ash can greatly reduce the seepage of water from the surface of subgrade to the interior. The fly ash shows great capacity in absorbing water,and results in large amount of frost heaving,being not suitable as the improved material. The moisture migration and amount of frost heaving reduced in the graded gravel mixed with cement. Compared with lime and fly ash,cement is the most suitable material to be mixed with graded gravel to reduce frost heaving.