加热限位管对冻土帷幕厚度的影响研究

The Effect of Heating Limit Pipes on the Thickness of Frozen Soil Wall

为解决现有人工冻结法施工后周围地层产生冻胀融沉所引发不良后果的问题,可设置加热限位管对冻土帷幕的发展进行限制,从而达到控制冻胀融沉的目的。运用有限元软件研究了设置加热限位管时对冻土帷幕温度场发展的影响规律,主要得出:加热限位管盐水温度每升高5℃,冻土帷幕厚度就减小约0.2 m;加热限位管循环5℃盐水时,在冻结30d前冻土帷幕厚度发展速度约0.05 m/d,之后由于加热限位管的作用,冻土帷幕不再向限位管以外发展,加热限位管作用效果明显;路径2各点温度一致,在冻结50 d时限位管盐水温度每升高5℃,其各点温度上升约1.5℃;在限位管开始循环热水前期,各点温度都有明显上升,离限位管越近温度所受影响越大;随着时间的推移,各点温度趋于稳定,循环热盐水温度越高,趋于稳定的温度值也越高。所得结果可为今后类似工程设计提供理论参考依据。

In order to solve the problems of adverse consequences caused by frost- thaw settlement of the surrounding formation after construction by using the existing artificial freezing method,the heating limit pipes can be set up to restrict the development of frozen soil so as to achieve the purpose of frost- thaw settlement control. The finite element software was used to study the influence of setting up heating limit pipes on the development of temperature field of frozen soil wall. The results indicated that the thickness of frozen soil wall was reduced by about 0. 2m as the brine temperature in heating limit pipe was increased by 5 ℃. When 5 ℃ brine was cycled in the heating limit pipes,the development speed of frozen soil wall thickness in the first 30 frozen days was about 0. 05 m / d.After that,the frozen soil wall no longer developed outwards due to the heating pipes,therefore the effect of heating limit pipes was obvious. The temperature of each point along path 2 was consistent,and the temperature rise in each point was about 1. 5℃ as the brine temperature in heating limit pipe was increased by 5 ℃ in the 50 th frozen day. The temperature in each point was obviously increased in the early stage of circulating hot water and the closer to the heating limit pipe the greater the impact. The temperature tended to stabilize along with time and the higher the temperature of circulating hot brine the higher the stabilized temperature. The results can provide a theoretical reference for future similar projects.