3D ground-penetrating radar has been widely used in urban road underground disease detection due to its nondestructive, efficient, and intuitive results. However, the 3D imaging of the underground target body presents the edge plate phenomenon due to the space between the 3D radar array antennas. Consequently, direct 3D imaging using detection results cannot reflect underground spatial distribution characteristics. Due to the wide-beam polarization of the ground-penetrating radar antenna, the emission of electromagnetic waves with a specific width decreases the strong middle energy on both sides gradually. Therefore, a bicubic high-precision 3D target body slice-imaging fitting algorithm with changing trend characteristics is constructed by combining the subsurface target characteristics with the changing spatial morphology trends. Using the wide-angle polarization antenna’s characteristics in the algorithm to build the trend factor between the measurement lines, the target body change trend and the edge detail portrayal achieve a 3D ground-penetrating radar-detection target high-precision fitting. Compared with other traditional fitting techniques, the fitting error is small. This paper conducts experiments and analyses on GpaMax 3D forward modeling and 3D ground-penetrating measured radar data. The experiments show that the improved bicubic fitting algorithm can effectively improve the accuracy of underground target slice imaging and the 3D ground-penetrating radar’s anomaly interpretation.

三维探地雷达以其无损、高效、结果直观等优点被广泛应用于城市道路地下病害检测。然而，由于三维雷达阵列天线之间的空间，地下目标体的三维成像呈现边缘板现象。因此，利用探测结果直接三维成像不能反映地下空间分布特征。由于探地雷达天线的波束极化较宽，发射特定宽度的电磁波时，两侧的强中能量逐渐降低。因此，将地下目标特征与变化的空间形态趋势相结合，构建了具有变化趋势特征的双三次高精度三维目标体切片成像拟合算法。算法中利用广角极化天线的特性构建测线间趋势因子，目标体变化趋势和边缘细节刻画实现了3D探地雷达探测目标的高精度拟合。与其他传统拟合技术相比，拟合误差小。本文对GpaMax三维正演建模和三维探地实测雷达数据进行了实验分析。实验表明，改进后的双三次拟合算法可以有效提高地下目标切片成像的精度和三维探地雷达的异常解译精度。目标体变化趋势和边缘细节刻画实现3D探地雷达探测目标高精度拟合。与其他传统拟合技术相比，拟合误差小。本文对GpaMax三维正演建模和三维探地实测雷达数据进行了实验分析。实验表明，改进后的双三次拟合算法可以有效提高地下目标切片成像的精度和三维探地雷达的异常解译精度。目标体变化趋势和边缘细节刻画实现3D探地雷达探测目标高精度拟合。与其他传统拟合技术相比，拟合误差小。本文对GpaMax三维正演建模和三维探地实测雷达数据进行了实验分析。实验表明，改进后的双三次拟合算法可以有效提高地下目标切片成像的精度和三维探地雷达的异常解译精度。