盾构出洞水平冻结解冻温度场三维有限元分析

3-D finite element analysis of melting temperature field in hield tunneling horizontal freezing reinforcing engineering

为揭示人工冻土解冻规律,对某地铁区间隧道盾构出洞水平冻结工程融化温度场进行了三维数值模拟分析,并研究了土体导热系数、比热容、含水率和环境温度等因素变化对人工冻土融化温度场的影响。计算结果表明:冻结帷幕解冻所需热量主要来自于与隧道管片和混凝土槽壁接触的大气;解冻过程可为负温阶段、相变阶段和正温阶段,土体温度在负温阶段上升较快,相变阶段上升速度明显变缓,进入正温区后土体温度回升速度再次增大;负温阶段受比热容的影响比较显著,含水率增大引起相变阶段明显延长,导热系数和环境温度变化对三个阶段都有显著影响。为跟踪注浆控制融沉提供了理论依据。

To reveal the thawing law of artificially frozen soil, the melting temperature field of horizontal freezing engineering project in the construction of subway hield tunneling was studied with the 3-D numerical simulation analysis. The effect of the thermal conductivity, the specific heat capacity and the water content of soil and the environmental temperature on the melting temperature field of artificially frozen soil were studied. The results show that most of the heat for thawing freezing curtain is from air contacting with tunnel segment and concrete groove wall, the thawing process includes the negative-temperature stage, the phase transition stage and the positive-temperature stage, and that the soil temperature increases fast in the negative-temperature stage, slows down in the phase transition stage and increases fast again in the positive-temperature stage. The results also show that the effect of specific heat capacity on the soil temperature in negative-temperature stage is significant. The increase of water content in soil causes the extension of the phase transition stage, and that the influence of thermal conductivity and environment temperature on all the three stages is significant. The findings provide theoretical support to grouting tracking and thaw settlement controlling.