隧道人工冻土帷幕边界雷达探测试验分析

在分析冻结法施工过程中冻土帷幕边界的传统判定方法优缺点，以及比较冻结土体与天然土体电性差异的基础上，结合上海复兴东路隧道联络通道的施工，开展了采用探地雷达方法对人工冻土帷幕边界进行判定的试验．通过正演模型试验了解了冻土边界的雷达反射波波形、振幅及相位特征；对实测雷达剖面进行非线性滤波处理，以消除隧道内的电磁干扰，并通过追踪同相轴判定冻土边界．雷达剖面解释结果与由测温孔监测资料推算出的温度场分布所反映的冻土边界能够较好地吻合，可以弥补测温法中测温孔数量少、元件损伤而导致数据丢失的缺陷．

Experiment on Artificial Frozen Soil Boundary Ground Penetrating Radar Detection in Tunnels

Based on the analysis of disadvantages of routine estimate for artificial frozen soil boundary and the comparison of dielectric properties differences between artificial frozen and natural soil,experiments on estimating the boundary by means of ground penetrating radar(GPR) were discussed for the cross-passage construction of Shanghai East Fuxing Road Tunnel engineering.To learn about the amplitude and phase features of GPR reflected wave from frozen soil boundary,forward modeling was also developed.The noise could be removed from primal GPR profiles by means of non-linear filtering,and the reflected wave from frozen soil boundary would be amplified.By tracing the in-phase the boundary could be estimated from GPR profile.The frozen soil boundary defined through GPR is consistent with the one indicated by the temperature field distribution derived from temperature-supervising data.Experimental results showed that GPR could supply a gap of temperature-supervising method during cross-passage construction in tunnels,such as the less temperature-supervising holes and data loss due to sensor damage.