地铁联络通道人工冻结法的数值模拟分析

Numerical Simulation Analysis of Artificial Freezing Method for Subway Contact Channel

以冻结管间距为0.3、0.4、0.5 m及其相应间距的单双排布置作为主要变量,考虑土的比热容、密度以及导热系数,建立热传递有限元模型对冻结法施工的积极冻结过程以及融化过程进行数值模拟。研究表明:当冻结管采用间距为0.3 m布置时,双排管会比单排管的制冷效果更加明显。同时发现冻结管间距越密集制冷效果会越高,从经济上考虑,冻结管的布置形式可以采用间距为0.4 m双排布置。在隧道中心竖向位置处,距离地表面越近,受到冻结后土体竖向产生的位移越大,在冻结帷幕内的冻土位移不随深度的变化而变化;在地表面距离隧道中心水平距离越大的位置,受冻土膨胀产生的竖向位移越小,在隧道中心处位移最大,同时发现地表水平方向的径向位移变化并不明显。

Taking the single and double row arrangement with freezing pipe spacing of 0.3,0.4,0.5 m and their corresponding spacing as the main variables,considering the specific heat capacity,density and thermal conductivity of soil,a heat transfer finite element model is established to numerically simulate the active freezing process and melting process of freezing method construction.The results show that the refrigeration effect of double row tubes is more obvious than that of single row tubes when the spacing of freezing tubes is 0.3 m.At the same time,it is found that the denser the spacing of freezing pipes,the higher the refrigeration effect.In terms of economy,the layout of freezing pipes can be arranged in double rows with a spacing of 0.4 m.At the vertical position of the tunnel center,the closer to the ground surface,the greater the vertical displacement of the frozen soil,and the displacement of the frozen soil in the frozen curtain does not change with the change of depth.The greater the horizontal distance between the ground surface and the tunnel center becomes,the vertical displacement caused by frozen soil expansion becomes smaller,and the maximum displacement is seen at the tunnel center.At the same time,it is found that the radial displacement change in the horizontal direction of the ground surface is not obvious.