准池铁路路基冻胀特性的试验研究

Experimental Study on Frost Heaving Characteristics of the Embankment Filler of Jungar Banner-Shenchi Railway

为探究准池铁路K44+970-K45+010路基的冻胀病害问题,通过现场调查、室内常规土性分析试验、毛细管上升高度试验,对该路段的冻胀发生条件进行分析。以初始含水率为变量,开展-20℃恒定冷端温度条件下的单向封闭系统冻胀特性试验。现场调查与室内试验结果表明:冻害路段位于高路堑地段,地下水位埋深为90 cm,路段周围汇水和下部地基蓄水条件良好,填料毛细管上升高度为70 cm,在冬季冻结锋面作用下地下水可以通过毛细水形式不断向上迁移至路基填料。冻胀特性试验表明:土样冻胀过程分为快速发展阶段、缓慢发展阶段和稳定阶段,初始含水率为10.6%和7.6%土样的最终冻胀量分别为5.6 mm和4.9 mm,冻胀率在7%左右,属于强冻胀敏感性土。冻胀量和冻胀率随初始含水率的增加而增大;而冻胀速率随初始含水率的增加而降低;水分重分布的峰值含水率与初始含水率呈正相关关系。冬季严寒天气下地下水在毛细作用下持续向路基填料补水是造成准池铁路路基冻害的主要原因。

In order to explore the frost heaving disease of K44+970-K45+010 of Jungar Banner-Shenchi Railway,the frost heaving conditions of this section were analyzed through field investigation,indoor conventional soil property analysis test and capillary rise height test.The frost heaving tests of unidirectional closed system under the condition of constant cold end temperature of-20℃was also carried out by taking the initial moisture content as the variable.The field investigation and indoor test results show that the frost damaged section is located in the high cutting section,and the buried depth of groundwater level is only 90 cm.The water catchment around the section and the water storage conditions of the lower foundation both facilitate the increase of moisture content of embankment filler,and the rising height of filler capillary is 70 cm.Under the action of freezing front in winter,groundwater can continuously migrate upward to embankment filler in the form of capillary water.The frost heaving tests show that the frost heaving process of soil samples is divided into rapid development stage,slow development stage and stable stage.The final frost heaving displacements of samples with initial moisture content of 10.6%and 7.6%were 5.6 mm and 4.9 mm respectively.The frost heaving rate is about 7%,which belongs to strong frost heaving sensitive soil.The frost heave displacement and frost rate both increase with the increase of initial moisture content,but the frost heaving rate decreases with the increase of initial moisture content.The peak water content after water redistribution is positively correlated with the initial water content.The main cause of this frost damage is the continuous replenishment of groundwater to embankment filler under the action of capillarity in severe cold weather during winter.