Study on electromagnetic field feature and probing effect about very deep buried pipeline

摘要

This paper describes the study on detecting particular deep pipelines installed by horizontal directional drilling in river crossing. It covers both the fundamentals of the technology and practical applications. The paper begins with the cylindrical magnetic field used for locating wires, pipes. Plots show the Hx, |Hz|, AHx curves and their own normalized profile curves with different depth from 1 to 21 meters separately , Plots also show their curves with 3 times electric currents with different depth from 3 to 21 meters separately. Also, the applicable condition on using Hx 70% for the determination of the depth of the underground pipeline is analyzed. The paper then proposes some probing technologic measures to confirm its location and depth. A description is given to raise signal-to-noise ratio, including direct connection, frequency, and electric current and far grounding and so on. The interferential factor on particular deep pipe line acquisition is studied. Finally, for showing the validity of this method, the paper describes two examples of probing long distance and particular deep pipelines whose depth is deeper than 5 meters in Guangzhou ,PRC.