Study Of Underground Shallow Sandstone And Pipeline With Ground Penetrating Radar

Ground penetrating radar(GPR) is now a well-accepted geophysical technique. The method uses radio waves to probe “the ground” which means any low loss dielectric material. Use the way of rapid, continuous, non-detection and have fast acquisition speed and high resolution. Ground-penetrating radar is widely used in the field of engineering, environmental, hydrological, geological survey, archaeological, geological survey, mineral exploration, military exploration of the planet detection. Like other detection method, ground penetrating radar has some limitations. Such as the existence of weak penetrating power several times spread to other serious clutter, uni-polar data acquisition to provide a limited amount of information, the impact of the antenna coupling shortcomings. Traditional ground-penetrating radar transmitting and receiving are the same linear polarized wave. In progress of the same offset distance measurement, the two antennas are placed side by side on the measured line. Transmitting antenna generate a linear polarized wave along antenna axis direction. From the nature of the linear polarized wave, we can see, the receiving antenna is most sensitive to the electric field parallel along the axis of antenna polarization. Since transmitting antenna and receiving antenna have the same polarization direction, only in the receiving antenna parallel along the axis of antenna electric field polarization components can be received.Electromagnetic radiation to the target surface, the target causes the polarization of electromagnetic wave to produce different degrees of rotation. Traditional ground-penetrating radar antennas only transmit and receive the same polarization direction of the reflection wave. It will cause the lack of information of the target reflectance. On the basis of the traditional ground-penetrating radar antenna, keep transmitting antenna polarization is fixed leaving the receiving antenna rotated 90°. We define H polarization which parallel with measurement lines, V polarization which perpendicular to measurement lines. So, there are four kinds of polarization antennas. They are HH, HV, VH, VV, where HH and VV called co-polarization mode, HV and VH called cross-polarization mode.This paper introduces how to measure the wild terrain with total station instrument and to do media sampling. What’s more, measuring the various physical parameters of the wild medium, compiling GprMax2 D by using the finite difference time domain(FDTD) method, practicing separately for shallow channel sandstone and Shallow Target(underground heat supply pipeline) according to the measured terrain and get accurate GPR forward profile after the terrain correction. The river sand layer, sand body size and shallow underground target body can be clearly presented in the forward section.After an integration processing of collected radar data and to use Pauli polarization to do migration imaging,it represented that forward profile and radar data are highly consistent and verifying that GPR has better recognition effect to river sand and shallow target body. Meanwhile, GPR forward modeling method provides a theoretical basis for practical measurement. The research result of this paper provides theoretical basis and possibilities for future petroleum exploration and broadening the application range of GPR.