Study On Three-dimensional Numerical Simulation And Characteristic Of Wavefield For Earth-rock Dam

With the requirement of economic development, the government pays a lot attention to water infrastructure construction. As a result, not only the planning speed of investment on water conservancy has been accelerated, but the detection of dam hidden defects has been planned normatively. How to detect dam hidden defects quickly and effectively is the premise of reinforcement. Use seismic wave detection technology, the objects’ kinematic and dynamic characteristics could be obtained. However, using this technology to detect the hidden troubles of earth-rock dam is still in the primary research stage. Under this background, based on the project of National Natural Science Foundation of China(NSFC)-The research of diagnosis technology in view of Dam hidden trouble based on the three-dimensional wave to electric field coupling by the holographic imaging, this thesis used several methods such as theoretical analysis, numerical simulation, signal processing and model test to study the influence of hidden troubles on three-dimensional wavefield of earth-rock dam. Besides, the method of judging the existence and position of hidden troubles preliminarily is proposed based on the research results. The main study contents and results are as follows:First of all, analyzing the basic characteristics of earth-rock dam and the forms of hidden trouble, based on which, setting the earth-rock dam equivalent to isotropic elastic body, and the generalized model for earth-rock dam and earth-rock dam with leakage passage are proposed respectively.Secondly, three dimensional finite model for analyzing the wavefield properties of earth-rock dam is built. The influence factors such as earthquake source, meshing and absorption boundary condition are studied, according to which, the suitable excitation means and the improved best adjustment coefficient of viscous-spring boundary condition are obtained.Thirdly, put finite element method in analyzing earth-rock dam with and without hidden trouble, the result shows that, when no hidden trouble exist in dam, there is no apparent scattered wave in vibrate signal of the spot in the top surface of dam. When hidden trouble exists, scattered wave which transmit around the hidden trouble would be motivated when direct wave encounter the hidden trouble. Observing the vibrate signal of the particle in top surface, a strong scattered wave can be seen after the direct wave. Based on these wavefield variation, the way of confirm whether there is hidden trouble in dam is suggestedFourthly, using finite element method, the influences of size, material and position of hidden trouble on wavefield are studied. Using time-frequency analysis method to analysis wavefield, the result shows that, wave-field characteristic is closely related to the hidden trouble. So, the way to determine the location of hidden trouble preliminarily based on the wavefield information is proposed.Finally, physical model of earth-rock dam is built, and the wave feature of which is tested under the condition that hidden trouble is exist or not. The result shows that the numerical simulation conclusion is approximately agree with the experimental. So, the conclusion gained by numerical simulation could be used in field test, which would improve test efficiency.