Research Of Pile And Bolt's Non-Destructive Test Technology Based On 3D Guided-Wave Theory

By means of theoretical and experimental study, combing with numerical simulation method, the NDT technology of piles and bolts are researched based on guided waves theory. Following conclusions are drawn:(1) The frequency equation in a traction-free pile is solved by Matlab. The guided waves dispersion relations provide information about group velocity, phase velocity, and attenuation as a function of frequency. Parametric analyses of pile's diameter,Young's modulus of concrete,Poisson's ration to dispersion relations are discussed in detail.(2) Results of parametric analyses show that the real part of the dispersion curves is not affected by boundary conditions, concrete-to-soil shear modulus ratio, concrete-to-soil density ratio, and soil type. However, these dispersion curves depend upon the Poisson's ratio of concrete. Attenuation curves are affected by boundary conditions, concrete-to-soil shear modulus ratio, density ratio, and soil type. The theory suggests that the usable frequency ranges for conventional NDT tests, defined as the frequency range where the propagation velocity is constant, are inversely proportional to cylinder diameter. The attenuation curves can be used to calculate the pile length that can be tested by this method.(3) The features of component at different resolution of the wavelet transform are extracted by using the properties of its better multi-resolution analysis. These features are fed into the wavelet neural network as the input patterns for training and classification. Then, it can be used to classify the pile defect .The results of numerical simulation show that this method is reasonable. The experiment research based on (3) shows that wavelet neural network which is trained successfully can be used to classify the defect type of pile as an intelligent classifier.(4) The stress distributions of bolt under pullout test are researched by theoretical analysis and numerical simulation. The pullout test is not good enough to evaluate the bonding quality because part strength of the bolt maybe bigger than the design strength.(5) The frequency equation of bolt is introduced by partial wave theory and layer matrix of a hollow cylinder. The amplitude ratio in some position which presented by numerical simulation is the same as which calculated by attenuation dispersion curve.