Identification of concrete voids in an untypical railway bridge pillar by Ground Penetrating Radar Method

摘要

The article presents the results of non-destructive testing, which was carried out on the concrete pillar with an unusual, trapezoidal shape and densely spaced reinforcement. After stripping the formwork, some surface voids became visible, which suggested that the existence of subsurface voids was also probable. The Ground Penetrating Radar method (GPR) was used to state whether these voids are formed and possibly to determine their approximate location. This paper discusses the adopted methodology of measurements, analysis and the GPR data processing. The interpretation of the echograms was based on a comparison of recorded GPR data with the modelling results MRS (FD) of electromagnetic wave propagation with the known geometry of the tested pillar. The results of detection are shown mainly in the form of the echograms (B-SCAN) and are collected as a cumulative sketch (C-SCAN). In order to assess the impact of the identified voids on the bearing capacity of the structure, the shell model of the pillar was built with the use of FEM. It shows stress distribution differences in the pillar with a continuous internal structure and in the pillar with the modelled voids. The obtained results were used for checking the bearing capacity of damaged pillar and during the preparation of the effective repair program.