不需提取激发脉冲的探地雷达波形反演方法

Waveform inversion of ground-penetrating radar data without needing to extract exciting pulse

利用麦克斯韦方程的波形反演方法,能充分利用雷达数据中反映地下介质特性的波形、走时、相位等信息.它要事先已知激发脉冲信号,需从实际资料中提取,但受到诸多因素的影响.本文尝试避免从实际雷达资料提取激发脉冲的方法.首先,借助于一个已知地质模型上的探地雷达系统采集的记录以及给定激发脉冲、给定激发接收天线的正演模拟信号,计算出转换算子.其次,将转换算子作用于实测雷达信号,将其转换成给定激发脉冲激发的、给定激发接收天线采集的信号.最后,用转换后的数据进行波形反演.二维模型数据的转换表明,转换后的数据与正演模拟数据一致,反演结果差异甚小.实验室实测数据的反演结果与实际情况相符.

The full-waveform inversion based on Maxwell equation is able to utilize all the information,such as wave shape,travel time and phase contained in radar data,which is the reflection of the medium.Full-waveform inversion requires the exciting pulse before the inversion is conducted.It should be extracted from observed radar data,and it is affected by various factors.This paper tries a method without needing to extract the pulse from measurement data.In the method a known geological model is required.A radar trace is collected on the model using the radar system,and a trace is simulated on the model using a given pulse and a couple of given transmitting and receiving antenna.These traces are then used to compute an operator,which is applied to the observed data.The observed data are transformed into the data as if acquired by the given pulse and given antennas.The transformed data are used for waveform inversion.Simulated ＂measurement＂ data from a two-dimensional geological model are transformed,and the transformed data are coincident to the simulated data obtained using the given pulse and given antennas.The inversion results from the transformed and simulated data are very close.The inversion result from laboratory experimental data agrees with the actual model.