Non-destructive method for evaluating local integrity of model piles using electromagnetic waves

Abstract

The objective of this study is to suggest a more accurate integrity estimation method in drilled shafts using electromagnetic waves propagating through transmission lines. Model piles, whose dimensions were 3.0 m in length, 0.2 m in height, and 0.2 m in width, were prepared. In the center of model piles along the length, the rebar and transmission line with 0, 1, 2, or 3 connectors were installed. In the middle of model piles, defect segments with length of 1.0 m were prepared The defect segments were filled with air, sands with different water contents, and water. The experimental results show that the velocity of the electromagnetic waves are dependent on the properties of the medium surrounding the transmission line. Although defects were detected in the transmission line without the connector, the location and size of defect were not clearly identified. However, for the transmission line with connectors, the location and size of sound and defect segments were more clearly identified using the velocity of electromagnetic waves determined between the connectors. This study suggests that transmission line with connectors may be effectively used for a more accurate evaluation of the integrity of drilled shafts.