Wave Field and Time-frequency Characteristics of Ground Penetrating Radar for Underground Cavity of Road

Abstract:

According to the distribution characteristics and electrical parameter design model of the underground medium of urban roads， the time-domain finite difference method and generalized S-transform were used to carry out the forward simulation and time-frequency feature extraction for the area of air-filled cavity， water-filled cavity， unconsolidated backfills and buried metal objects under the road. The results show that the event of reflected waves at the top interface of underground cavities is in the shape of arc reflection， but the reflected wave energy of air-filled cavities is stronger than that of water-filled cavities. The central frequency of the area of underground cavity is concentrated in a low frequency range， and the other frequency components are evenly distributed. There will be two high-amplitude energy clusters in the area of the buried metal， and the frequency distribution is scattered. The frequency of the area of the unconsolidated backfill fails to show a obvious pattern. Finally，an engineering case study verified the reliability of numerical simulation.