Underwater concrete contact rebound detection testing and its correction methods

Chen Haikuan; Zhang Kai

doi:10.3969/j.issn.1000-1123.2025.06.006

Abstract：Long-distance water conveyance culverts are primary hydraulic structures in water diversion projects,typically deeply buried with undulating pipelines,making them susceptible to prolonged scouring and erosion by high-velocity sediment-laden flows.Under such complex hydraulic conditions and harsh service environments,underwater concrete structures are prone to material performance degradation.Ensuring the safe operation of these culverts necessitates strengthening the assessment of underwater concrete structural strength.Existing rebound testing instruments are designed for dry conditions and face challenges in underwater applications,such as water ingress leading to malfunction.To address this,conventional mechanical rebound hammers were modified by injecting high-pressure gas to expel water,resulting in the development of an underwater contact rebound device capable of rapid non-destructive testing of hydraulic structures within a certain depth range.By analyzing the relationship between rebound values under water pressure and those in dry conditions,underwater concrete rebound conversion coefficients were calibrated through laboratory experiments.These findings were applied to the underwater inspection of the long-distance culvert in the Liutang River,Huai'an City,Jiangsu Province,where the underwater concrete rebound conversion coefficients were calibrated,and the underwater rebound measurements were corrected and verified.The results demonstrate the feasibility of the underwater contact rebound device and correction methods,providing a technical means for assessing the strength of underwater concrete in long-distance culverts that cannot be dewatered.