Research on FDTD-PML Algorithm for Magnetic Anomaly Analysis and Length Detection of Rebar

Pile foundation mainly provides support and bearing function for buildings, deeply buried underground belongs to hidden engineering, non-destructive detection of reinforcement length within the pile foundation has become a research hotspot. The research theoretically explains the method and principle of magnetic anomaly detection of rebar burial depth, and develops the pile length detection equipment. The FDTD-PML algorithm is used to calculate the magnetic field strength on the surface of rebar, combined with MATLAB and ANSYS-MAXWELL software simulation to analyze the electromagnetic wave propagation on the surface of rebar in the ground, and the pile length detection equipment is developed, combined with the actual testing of the Za vertical magnetic component curve of the south side and the north side of the drilled pile on the site. The experimental results show that, using the developed magnetic anomaly detection equipment based on the depth of rebar, the changes in the magnetic curve of “two peaks clamped by a valley” correspond to the length of the pile foundation, and when the pile hole spacing is increased to 1.5 meters, the measurement error is only 0.3 meters, which is of good performance and high practical application value.