Forward Modeling Of Rayleigh Wave Propagation Response Oriented To Non-destructive Testing Of Concrete

As we all know,concrete is a necessary support material for civil engineering,transportation,and hydraulic engineering.With the development of social economy,the demand for concrete is increasing day by day.Concrete is made by mixing and hardening sand and stone according to a certain ratio.When the ratio of sand and stone is improper or the external force is uneven,cavities and cracks will develop inside the concrete,threatening the safety of concrete use.Therefore,non-destructive testing of concrete structures has always been an important direction for the development of the engineering field.At present,the commonly used methods include rebound method,ultrasonic method,radar method,shock echo method and local(semi,micro)damage method,etc.,mainly using wave travel time information.In recent years,considering the full use of multi-channel wave waveform information,the Rayleigh surface wave method has received more and more attention.The Rayleigh surface wave dispersion effect is sensitive to changes in the concrete material structure.At the same time,the characteristics of concrete structures at different depths can be obtained by adjusting the seismic source and the parameters of the observation system,so as to achieve fine detection of concrete structures.Due to the influence of various factors such as primary cracks and external forces,the scale,shape,and tendency characteristics of the internal cracks in the concrete are comprehensively developed,and the response characteristics of the Rayleigh wave propagation wave field are complex.In order to analyze the propagation characteristics of Rayleigh waves in concrete cracks,this paper uses the finite element method to realize twodimensional and three-dimensional numerical simulations of the propagation of concrete Rayleigh waves.The key points are the grid size,source parameters,boundary conditions,element and integration step selection,etc.The problem was analyzed.The typical concrete samples are abstracted into digital models with no cracks and cracks of different scales.Based on the finite element method,the full wavefield simulation of the seismic wave field is realized,and the propagation characteristics of the Rayleigh wave,such as travel time,waveform,frequency spectrum,and dispersion,are comprehensively compared.analysis.Studies have shown that the spectral ratio and cutoff frequency of reflected and transmitted Rayleigh waves can be used to quantitatively estimate the crack depth;the inflection point of the zigzag dispersion curve of reflected Rayleigh waves can be used to quantitatively estimate the crack depth.The research in this paper verifies the feasibility of using Rayleigh wave to carry out non-destructive testing of concrete.The comprehensive use of Rayleigh wave information for fine detection of concrete structures has laid a good foundation.