ASSESSMENT OF THE TECHNICAL CONDITION OF CONCRETE AND REINFORCED CONCRETE HYDRAULIC STRUCTURES USING 3D ULTRASONIC TOMOGRAPHY

Abstract

The article presents the results of assessing the technical condition of the concrete and reinforced concrete structures of the emergency spillway of the Tasotkel Reservoir using the 3D ultrasonic tomography method based on the Betonoskop SK-1700 3D system. The study is aimed at detecting hidden defects, evaluating the internal structure of concrete, and analyzing deterioration processes under long-term seepage, hydrodynamic, and seismic impacts. During the investigation, spatial ultrasonic scanning of a 10×10 m section was performed with a diagnostic depth of up to 0.60 m. Three-dimensional tomographic models, ultrasonic wave velocity distribution maps, vertical and transverse sections, and engineering interpretations of defect zones were developed. It was established that the average ultrasonic wave velocity was approximately 3280 m/s, while minimum values in critically deteriorated areas decreased to 1680-1850 m/s. More than 35% of the investigated structural volume was found to be in a state of severe and critical deterioration, while the proportion of potentially hazardous zones associated with internal voids and loss of bonding accounted for approximately 6-8%. The most critical defects were localized in the lower part of the concrete lining and within the concrete-foundation interface zone, where seepage-induced moisture accumulation, structural loosening, delamination, and local void formation were identified. Correlation analysis confirmed a stable relationship between defect depth and the reduction in ultrasonic wave velocity. The agreement coefficient between the 3D ultrasonic tomography results and visual inspection/local opening investigations ranged from 0.79 to 0.88, while the overall diagnostic reliability reached 91-95%. The obtained results confirm the high efficiency of the Betonoskop SK-1700 3D system for diagnosing hidden defects in concrete and reinforced concrete hydraulic structures and can be applied for inspection, monitoring, and assessment of the operational reliability of hydraulic infrastructure facilities.