From the experience of the technical examination of hydro-technical tunnels

Abstract

Abstract A comprehensive methodology is proposed and the results of the technical examination of hydraulic tunnels are given. The technique takes into account the influence of water flow, the formation of cavities behind the shell, fixes defects, and reveals the prerequisites for their formation. It consists of visual inspection and non-destructive testing (ultrasonic, electromagnetic, vibro-acoustic). A unified presentation of the examination results is proposed. The optimal basis and operating frequency of the ultrasonic method are substantiated. The gradations of the processes of the formation of cracks in concrete are determined by the frequency of electromagnetic radiation. Examples of tunnel examination are given. Characteristic areas of the objects are identified. For main canals, this is a shell near the entrance and exit portals. Cavities behind the shell can be traced along the entire length of the tunnels. The main defect of the shells of pressure tunnels of power plants is cracks in the reinforced concrete lining. For structures of seasonal drainage, filtration in the bottom is characteristic. The examination results are used to develop projects for repair works. Some methodical regulations can be used for inspecting any underground structures.