Surface Wave Method To Detect Ship Lock Of Concrete Crack Technology Research

The assessment of the cracks in concrete is important for the condition evaluation of concrete structures. Several nondestructive techniques are used to characterize the surface-opening crack depth in concrete, such as ultrasonic spectroscopy method, impact echo method, radiology, acoustic emission method, impulse echo method, radar method, infrared thermograph.When identifying the depth of cracks, especially those with great depths, the impact echo method and impulse echo methods always fail due to the rapid energy attenuation of P wave.In this dissertation, Surface Wave Spectral Energy Transmission Method is used to estimate the depths of surface-opening deep cracks in concrete.First, the surface wave spectral energy transmission method is investigated. The self-calibrated surface wave transmission function is measured, and the spectral energy transmission ratio is calculated. The effect of concrete mix and the crack depths on surface wave transmission is investigated through experiments. It is found that the spectral energy transmission ratio can be effectively used for the crack depth estimation of concrete structures.Then, the amplitude factor method is investigated. The amplitude factor is defined as the ratio between R-wave amplitude of the receiver and the source. The relations between amplitude factor and normalized crack depth were investigated.. An exponential regression was derived. A reasonably good correlation was obtained.Last, the effect of reinforcement and number of cracks on the surface wave spectral energy transmission is investgated. Specimen with a single layer reinforcement and double layer reinforcement are prefabricated with cracks of different depth.