探地雷达地下空洞图像识别技术研究

Research on underground cavity image recognition technology of ground penetrating radar

探地雷达技术研究大部分局限于各向均匀介质的正演模拟,而实际地下空洞很少存在规则形状的情况,导致探地雷达在地下隐患特别是空洞及脱空探测工作中按常规的理论判断识别率不高。为了解决这一问题,基于电磁波的传播理论,通过室内数值模拟和实际案例对比分析雷达反射波在地面及地下隐患分界面的相位和振幅强度的情况,分析可知地面反射波的振幅较强,其相位和雷达发射源的相位相反,而空洞及脱空的上界面反射波的振幅同样较强,而其相位与雷达发射源的相位相同,且同地面反射波的相位相反。因此在实际工作中,可以通过疑似异常反射波的振幅强度及其相位与地面反射波相位的关系,配合地下隐患的其他特征如尖端绕射、底层反射波等来提高地下隐患的识别准确率。

Most of the research on GPR technology is limited to the forward simulation of isotropic uniform medium,but the actual underground cavity rarely has regular shapes,which leads to the low recognition rate of GPR in the underground hidden danger,especially the cavity and void detection work,according to the conventional theory.In order to improve the recognition accuracy of ground penetrating radar in underground hidden dangers,especially cavity and void detection,this paper analyzes the phase and amplitude intensity of radar reflected wave at the interface between ground and underground hidden dangers through indoor numerical simulation and actual case comparison.Through the analysis,it can be seen that the amplitude of ground reflected wave is strong,and the phase is opposite to that of radar transmitting source.The amplitude of the reflected wave on the upper interface of the cavity and void is also strong,and its phase is the same as that of the radar transmitting source and opposite to that of the ground reflected wave.Therefore,in practical work,the identification accuracy of underground hidden dangers can be improved by combining the amplitude intensity and phase relationship of ground reflected waves and suspected abnormal reflected waves with other characteristics of underground hidden dangers,such as tip diffraction and bottom reflected waves.