钻孔埋管注盐法整治季节冻土区路基冻害现场试验研究

以季节冻土区青藏铁路环青海湖段路基冻害为背景,通过选取典型冻害断面,从水分、温度和土性三个方面分析了环湖段路基冻害成因。根据路基病害处理中成熟应用的注浆和注盐法,提出采用钻孔埋管注盐法整治路基病害技术,通过现场冻胀观测,检验注盐法整治路基的有效性。结果表明:环湖段路基冻害主要是由于路基土体内存在一层低液限低渗透性的粉质黏土,黏粒含量高,含水率大,冻深最大为1.5 m,粉质黏土层冻结,引起路基冻胀。结合现场试验段,对用盐量、盐的成分、施工工艺与参数提出合理的施工建议。现场冻胀监测表明,钻孔埋管注盐段路基的冻胀量明显降低,可用于季节冻土区路基冻害的整治治理。

Field test study on railway subgrade against frost damage in seasonally frozen ground areas by using salt injection method

Based on the frost damage of Qinghai Lake section of the Qinghai-Tibet Railway, in this paper, the causes of frost damage of the subgrade are analyzed from three aspects, namely, water, temperature and soil by selecting a typical frost damage section in the seasonally frozen ground areas. According to the grouting and salt injection method, which has been applied maturely to treat subgrade disease, a new method has been put forward to treat the subgrade disease by drilling and injecting salt. Furthermore, the effectiveness of this method can be monitored by observing frost heave in-situ. The results show that the damage to the subgrade in the lake section is mainly due to a layer of silty clay, characterized with low-liquid limit and low-permeability, in the subgrade, of which the clay content and water content are high, resulting in the maximum frozen depth reaching 1. 5 m;the silty clay freezing causes frost heaving to the subgrade. Based on the in-situ test, reasonable construction sugges-tion is put forward, including the amount of salt and its composition, construction technology and parameters. In-situ frost heave monitoring shows that the amount of frost heave in the road section which has been drilled and injected salt is significantly reduced. Thus, the method can be used to deal with the frost damage of subgrade in the seasonally frozen ground areas.