Buried pipeline detection technology scheme (1) - ground penetrating radar

Buried pipeline detection technology Scheme (1)

First, geological radar test

(1) Basic principles

Ground Penetrating Radar is a kind of instrument with high frequency electromagnetic wave to detect underground objects. It mainly uses one antenna to transmit high frequency broadband electromagnetic wave and another antenna to receive the reflected wave from the surface of underground medium. When the electromagnetic wave propagates in the medium, its path, electromagnetic field intensity and waveform will change with the electrical properties and geometry of the medium through which it passes. Therefore, according to the received wave travel time (also known as two-way travel time), amplitude and waveform data, the distribution of underground media can be inferred

(2) Reflection coefficient of electromagnetic wave

The reflection coefficient of electromagnetic wave depends on the difference of the relative dielectric constant of the medium on both sides of the interface. When the target object has a large difference in the electromagnetic parameters of the surrounding medium, the reflection coefficient is also large, so the energy of the reflected wave is also large. The reflection coefficient is related to the incidence Angle and the water content of the medium. When these differences are greater, the reflection coefficient is greater, and this difference is the physical premise of ground penetrating radar detection. In the process of electromagnetic wave propagation in the medium, when encountering geological phenomena with obvious changes in relative dielectric constant, electromagnetic wave will produce reflection and transmission phenomenon, and the distribution of reflection and transmission energy is mainly related to the electromagnetic wave reflection coefficient of the interface with abnormal changes:

(3) Data collection and processing methods

The geological radar system is composed of integrated main engine, antenna and related accessories. The specific working principle is: when the radar system uses the antenna to send a wide-band high-frequency electromagnetic wave underground, the electromagnetic wave signal will be reflected, transmitted and refracted when it encounters the dielectric interface with large dielectric difference when propagating in the medium. The greater the difference between the dielectric constants of the two media, the greater the reflected electromagnetic wave energy. After the reflected electromagnetic wave is received by the receiving antenna that moves synchronously with the transmitting antenna, the radar host accurately records the motion characteristics of the reflected electromagnetic wave, and then processes it through signal technology to form a full-section scan map. Geological radar profile scan is shown in the figure.

Sample geological radar profile