人工冻结法调控多年冻土区桩基础地温场的效果分析*

为了解决青藏铁路运营过程中，由于多年冻土地基的升温退化，部分多年冻土区桥梁桩基础承载性能下降，产生有害沉降变形，进而造成桥梁上部结构移位破坏，甚至部分桥梁桩基础在短时间内产生较大的沉降变形这一严重问题。基于当前多年冻土区桥梁桩基础沉降病害快速抢修技术空缺，提出人工冻结技术处置多年冻土区桥梁桩基础沉降病害的新设想，利用数值软件建立冻结管-桩基础三维模型分析该技术的可行性与调控效果，分析冻结参数、场地冻土条件等对冻结效果的影响。研究结果表明:人工冻结法可以快速降低桩周多年冻土温度；同时，冻结96 h可以对桩基地温场起到较好的冷却效果；冻结管至桩的距离对冻结效果的影响最为显著，冻土的含冰量越大，则降温速率越慢。

Effect analysis of artificial freezing method to regulate ground temperature field of pile foundation in permafrost regions

In order to solve the problem that in the operation process of the Qinghai-Tibet Railway,due to the heating and degradation of the permafrost foundation,the bearing performance of the bridge pile foundation in some permafrost regions decreased,resulting in harmful settlement deformation,which in turn caused the displacement damage of the bridge superstructure,and even the large settlement deformation of some bridge pile foundation in a short period of time,based on the current vacancy of rapid repair technology for the settlement diseases of bridge pile foundation in permafrost areas,a new idea of using the artificial freezing technology to deal with the settlement diseases of bridge pile foundation in permafrost regions was proposed.The three-dimensional model of frozen pipe-pile foundation was established by numerical software to analyze the feasibility and regulation effect of this technology,and the influence of freezing parameters and site frozen soil conditions on the freezing effect was analyzed.The results showed that the artificial freezing method could quickly reduce the temperature of permafrost around pile.At the same time,freezing 96 h could play better cooling effect on the ground temperature field of the pile foundation.The distance from the frozen pipe to the pile had the most significant effect on the freezing effect,and the greater the ice content of frozen soil,the slower the cooling rate.