高速铁路岛状多年冻土区钻孔桩施工技术研究

Research on Construction Technology of Bored Pile in Island Permafrost Area of High-Speed Railway

高速铁路岛状多年冻土区钻孔灌注桩在保证桩身稳定性和承载力前提下施工具有可行性,但需采取必要的施工控制措施。本文以小兴安岭南麓,沿线穿越多处岛状多年冻土的铁力至伊春高速铁路钻孔桩基础为研究对象,研究了冻土区的施工工艺和施工方案。结果表明:(1)旋挖钻机可用于高速铁路岛状多年冻土钻孔桩的施工;(2)可采用双层护筒钻孔桩施工,冻土段位于承台及以上的护筒分段钻进下放护筒,冻土段位于承台底及以下的采用双层长护筒施工;(3)导管采用分段吊装入孔技术,提前分段将导管组装完成,减少吊装过程中使用的连接接头;(4)泥浆可根据现场条件采用膨润土造浆;(5)钻孔灌注桩清孔后的泥浆性能指标应符合要求。值得注意的是施工时及时安装温度传感器以掌握周围温度场情况,在施工后采取保温隔热措施减小冻深。

It is feasible to construct bored piles in permafrost island of high-speed railway under the premise of ensuring the stability and bearing capacity of piles,but necessary construction control measures should be taken.In this paper,the construction technology and construction scheme of Tieli-Yichun High-Speed Railway are studied by taking the bored pile foundation crossing many island permafrost along the southern foot of Lesser Khingan Mountains as the research object.The results show that:(1)rotary drilling rig can be used in the construction of bored pile in island permafrost section of high-speed railway;(2)double-liners protective cylinder bored pile can be used for construction.The protective cylinder of frozen soil section located at or above the cap can be drilled and lowered by sections,and the double-liners long protective cylinder of frozen soil section located at or below the cap can be used for construction;(3)the pipe adopts the technology of piecewise lifting and holing to assemble the pipe in sections in advance so as to reduce the use of connecting joints in the lifting process;(4)slurry can be made by bentonite according to site conditions;(5)the mud performance index of bored pile after clearing the hole should meet the requirements.It is worth noting that temperature sensors should be installed in time to grasp the surrounding temperature field during construction,and thermal insulation measures should be taken to reduce the freezing depth after construction.