基于瑞利波法对混凝土表面裂缝检测的数值研究
Numerical simulation on detection of concrete surface crack based on Rayleigh wave method

基于瑞利波及衍射纵波的传播时间差法，利用有限元法分析了瑞利波在含不同长度及角度裂纹的混凝土介质中的传播规律，提出了混凝土介质中表面裂缝长度和角度的计算公式，并验证了数值模拟结果的准确性。研究结果表明：在传播过程中，瑞利波一部分沿着介质表面（含裂纹表面）传播，另一部分在裂缝尖端发生模式转换，形成衍射横波和衍射纵波，弹性波传播到介质边界时被粘弹性人工边界全部吸收，消除了反射波的影响；表面裂缝长度和角度的计算结果误差基本在5%以下，只有个别数据误差较大，在一定范围内，随着裂缝长度和角度值的增大，计算结果的准确度越高。
The formulas for the length and angle of surface crack are obtained based on the difference of propagation time of Rayleigh wave and the diffracted Longitudinal wave. Propagation rule of Rayleigh wave is analyzed in accordance with different depths and angels of surface cracks using the finite element method. The simulation results were validated calculations and the simulation accuracy is proved. Results indicatevia:1) During propagation of Rayleigh wave, a proportion propagates along the medium surface (including the crack surface); The remaining is subjected to mode conversion phenomenon, and becomes the diffracted transverse and longitudinal wave. All of the elastic waves are absorbed by the viscoelastic artificial boundary when they come to the border of the medium, which eliminates the influence of the reflected wave. 2) Calculation errors of the length and angle of surface crack are substantially below 5%. Within certain ranges, the calculation accuracy is higher as the values of lengths and the angles of the surface crack increase.