Complex analysis of GPR signals to control contact zone of concrete lining and rock mass

Nondestructive sensing technologies are essential for assessing the condition and structural integrity of concrete linings and their surrounding rock. This study utilized ground-penetrating radar (GPR SIR-3000) to detect defects, specifically a dry sand-filled void embedded within a concrete lining. Recognizing that accurate characterization of GPR signals is crucial for understanding the interface between concrete linings and rock mass, the researchers employed the finite-difference time-domain (FDTD) method to simulate electromagnetic wave propagation through concrete models. This approach allowed them to investigate defects in the form of internal thin layers or voids within concrete structures. By combining experimental measurements with forward simulations, the study focused on determining defect thickness using the amplitude ratio method, which enhances measurement accuracy. The experimental findings were found to be consistent with the simulation predictions. Further signal processing techniques, including time delay analysis and spectral analysis, were also applied. The results of this research demonstrate the potential of GPR technology for characterizing defects at the interface between concrete linings and rock mass, or within the surrounding rock mass itself, providing valuable insights into defect thickness and the electromagnetic properties of the materials filling these voids.