Design of a reinforcement length inspection device based on 3D magnetic field measurement

In case weak magnetization of rebars in the vertical direction leads to insignificant changes on the curve of the vertical magnetic component near the bottom of a reinforcement cage, signatures of changes on the curve of the total magnetic field intensity was used instead for the length inspection of the reinforcement cage. A reinforcement cage length inspection device based on the measurement of three-dimensional magnetic field was presented. This device consists of a probe with a 3-axis magnetometer and an inspection controller that supports wired and wireless communication with computer. The fulfillment and reliability of the device were verified by a field test conducted on a bored pile. The test results showed that it was rational and feasible to determine the reinforcement cage length based on the measurement of three-dimensional magnetic field.