A NDT Method for Location and Buried Depth Measurement of Rebars in Concrete Pole

Abstract

Accurate measurement of buried depth of rebars can effectively judge the durability of the Reinforced Concrete (RC) structure. However, most of the existing measurement methods cannot determine the deflection of rebar and do not consider the influence of factors such as the diameter and spacing of rebars, which resulting in low buried depth measurement accuracy. Therefore, this article takes the vertical rebars in concrete pole as the research object, and proposes a non-destructive method for location and buried depth measurement based on the magnetization effect. First, this article analyzes the influence of the magnetization effect excited by the rebars on the original magnetic field, and then designs the sensor layout to measure the magnetic induction intensity at different positions. Secondly, the central axis position and deflection angle of rebars are determined through comparing the measured data, and the buried depth is derived by applying the Support Vector Regression (SVR) algorithm. In addition, the proposed method is verified through simulation and experiments. Finally, this article discusses the influence of the diameter and spacing of rebars on the buried depth measurement, and uses the influencing factors as the inputs of the SVR algorithm model to correct the prediction results, which effectively reduces the maximum measurement error from 2.15mm to 0.36mm.