不同水分条件下探地雷达电磁波波速估算方法与对比分析

通过对地下管线在雷达图像的响应特征的分析，提出了基于Levenberg-Marquardt的一种双曲线拟合计算电磁波速的方法，在此基础上，采用GR-Ⅲ型探地雷达系统对不同土壤含水条件下的地下管线进行探测，并将该方法应用于地下管线深度的提取，并与介电常数法和已知埋深反算法计算结果进行了精度的对比分析。结果显示：土壤体积含水量由17.020%增至25.333%时，基于Levenberg-Marquardt算法的双曲线拟合法计算电磁波速与实际值的差值均约为0.9 cm/ns，误差率约为8%，而基于介电常数法计算结果的误差由1.097 cm/ns增至1.670 cm/ns，误差率由9.613%增至16.510%。研究结果表明，基于Levenberg-Marquardt算法的双曲线拟合法更简便有效，适用于野外不同水分条件下的未知埋深的地下管线的空间位置检测工作。

Estimation method and comparative analysis of ground penetrating radar electromagnetic wave velocity based on different water contents

Through the analysis of the response characteristics of underground pipe in GPR image，a method of hyperbolic fitting based on Levenberg Marquardt algorithm to calculate the electromagnetic wave speed was presented.On this basis，underground pipe was detected by GR Ⅲ ground penetrating radar under different soil water contents in experiment model，and the new method was used to calculate the depth of underground pipe.The calculation was compared with some traditional methods such as Permittivity method and the anti calculate algorithm under the known depth.The results show when the soil moisture content increases from 17.020% to 25.333%，the all errors of the -electromagnetic wave of the new method is about 0.9 cm/ns，the error rate is about 8%.However，the permittivity method’s error increases from 1.097 cm/ns to 1.670 cm/ns，the error rate range from 9.613% to 16.510%.The results indicate that the hyperbolic fitting under Levenberg Marquardt algorithm is more applicable to detect the spatial location of the underground pipe under the different water conditions.