季节冻土地区高速铁路路基设计

哈大和哈齐铁路是季节冻土地区高速铁路无砟轨道路基冻胀变形控制方面非常具有代表性的工程,本文通过对两个项目防冻胀设计措施、变形监测结果及相关研究成果的介绍,阐述了对路基防冻结构、防冻层厚度、防冻填料技术要求、路基冻胀变形发展规律等的认识:(1)混凝土基床是特殊条件下的路基防冻解决方案,一般应满足地下水位较高或常年积水且不具备降排水条件的低路堤地段;(2)季节冻土地区采用填料填筑的路基会发生冻胀变形,防冻层填料满足一定要求前提下,冻胀变形不会影响线路平顺性,可以保证高速铁路安全平稳运营;(3)冻胀变形小于4 mm的百分比随着时间的推移逐渐增加是东北地区各条高速铁路路基冻胀变形的共同特点,说明路基抗冻胀变形能力的稳定需要一定的时间;(4)反复出现的大的冻胀变形往往是填料细颗粒含量超标较多或者明显排水不畅的地段。施工期通过变形监测及时发现可能形成冻害的隐患并进行治理是非常重要的。

Design of High-speed Railway Subgrade in Seasonal Frozen Soil Area

Harbin-Dalian railway and Harbin-Qiqihar railway are the representative projects in frost heaving deformation control of high-speed railway ballastless track subgrade in seasonal frozen soil area.Through introduction of anti-frost heaving design measures,deformation monitoring results and the related research results of these projects,the paper presents the understandings of anti-freezing structure of subgrade,thickness of anti-freezing layer,technical requirement of anti-freezing filler and development law of subgrade frost heaving deformation as follows:(1)Concrete bed is the solution to subgrade antifreeze under special conditions,which should meet the requirements of the low embankment section with high underground water level or perennial standing water and no drainage conditions.(2)Frost heaving deformation occurs in the subgrade filled with filler in the seasonal frozen soil area.If the filler for anti-freezing layer meets certain requirements,the smoothness of the line will not be affected by frost heaving deformation,which can guarantee the safe and stable operation of high-speed railway.(3)The percent that the frost heaving deformation is less than 4mm gradually increases as time goes on,which is the common characteristic of subgrade frost heaving deformation for all high-speed railways in Northeast China,and shows the stabilization of subgrade anti-frost heaving deformation ability needs a certain time.(4)The large frost heaving deformations occur repeatedly in the sections where the fine particle content of the filler exceeds the standard or the drainage is obviously poor.It is very important to find out the hidden troubles of frost damages and control it in time by deformation monitoring during construction.