Long-term monitoring of spillway using various NDT techniques-case studies

Abstract

Abstract The erosion under a spillway can be a long-term issue that threatens the structural integrity of a water reservoir. The heavy rainfall associated with storms or typhoons could cause a serious flood if the spillways do not function properly. The spillway under investigation was suspected to be defective after they had been commissioned in 1987. Potholes and subsurface cavities were confirmed in the safety assessment using various NDT techniques including ground penetrating radar and impact echo. The engineering team applied the repair project that aimed to remedy the deteriorating concrete structure. The GPR inspection was able to differentiate the repaired region from the cavities under concrete slabs. The results were verified against other measurement data obtained independently. Hence, the GPR technique is effective for quality check of grouting repair of spillways. Repetitive GPR scans were also carried out after the rehabilitation of spillways. Not only the quality of repair can be evaluated, but the scans were also provided as the baseline record for long-term condition assessment of the spillway-reservoir system in the future.