Near Surface Velocity Estimation Using GPR Data: Investigations by Numerical Simulation, and Experimental Approach with AVO Response

Ibrar Iqbal,Yang Yang,Gang Tian,Xiong Bin,Sun Hanwu,Honghua Wang,Zahid Masood,Peng Sanxi

doi:10.3390/rs13142814

Abstract

The velocity of near-surface materials is one of the most important for Ground-Penetrating Radar (GPR). In the study, we evaluate the options for determining the GPR velocity to measure the accuracy of velocity approximations from the acquired GPR data at an experimental site in Hangzhou, China. A vertical profile of interval velocities can be estimated from each common mid-point (CMP) gather using velocity spectrum analysis. Firstly, GPR data are acquired and analyzed using the popular method of hyperbola fitting which generated surprisingly high subsurface signal velocity estimates while, for the same profile, the Amplitude variation with offset (AVO) analysis of the GPR data (using the same hyperbola fitting method) generate a more reasonable subsurface signal velocity estimate. Several necessary processing steps are applied both for CMP and AVO analysis. Furthermore, experimental analysis is conducted on the same test site to get velocities of samples based on dielectric constant measurement during the drilling process. Synthetic velocities generated by AVO analysis are validated by the experimental velocities which confirmed the suitability of velocity interpretations.

Highlights

Ground-Penetrating Radar (GPR) is a non-destructive geophysical technique used to image near-surface since it is beneficial for subsurface prospection
The experimental velocities are similar to the common depth point (CDP) values but do not match as Amplitude variation with offset (AVO), confirming the study’s main goal
Precision velocity model estimation is critical for high-quality GPR surveys

Summary

Introduction

Ground-Penetrating Radar (GPR) is a non-destructive geophysical technique used to image near-surface since it is beneficial for subsurface prospection. The research community has shown their great interest in it especially for archaeological field surveys [1,2], GPR has been used to image linear subsurface structures [3]. Simple ground penetrating radar mapping has been used for determining soil stability [5]. The data can be used to estimate the radar signal velocity distributions versus subsurface depth [6]. A method that uses the frequency dependence of the material has been recently established through the removal of the dispersion curve, which yields the phase velocity of the frequency from a CMP acquisition on concrete [7]. GPR data have been used for water contamination detection, for example [8,9]

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Conclusion