考虑多地层相变的地铁联络通道三维冻结温度场数值模拟

地铁联络通道冻结法施工地层一般为多地层,各地层相变潜热具有差异性,尤其是富水卵砾石层差异较大,目前分析普遍考虑单一地层或极少数地层相变潜热,难以反映真实情况。依托南宁地铁联络通道冻结法施工工程,建立三维瞬态导热模型,并考虑多地层相变潜热,对联络通道的冻结温度场进行探究。结果表明,积极冻结约20 d,冻结圆柱逐渐增加并开始交圈;冻结43.22 d后,冻结帷幕的平均温度下降至-10℃以下。现场温度实测值与数值模拟结果温降趋势基本一致,与模型试验相差较远。

Numerical Simulation of 3D Freezing Temperature Field of Metro Connection Channel Considering Multi-layer Phase Transition

The stratum where the freezing method is used to construct the subway communication channel is generally multi-stratigraphic,and the latent heat of phase transition in different layers is different,especially for rich water layer and gravel layer.At present,the analysis generally considers the latent heat of phase transition of a single layer or very few layers,which is difficult to reflect the real situation.Taking Nanning subway communication channel project using freezing method construction as study object,a three-dimensional transient thermal conductivity model is established,and considering the latent heat of multi-layer phase transition,the freezing temperature field of the communication channel is explored.The results show that,after about 20 days of active freezing,the frozen cylinder gradually increases and begins to overlap,and after freezing for 43.22 d,the average temperature of the frozen curtain drops below-10℃.The measured temperature change of the field is basically consistent with the temperature drop of the numerical simulation,but it is much different from the results of model test.