非线性波在岩石节理处的透射规律研究

Transmission Law of Nonlinear Wave across Jointed Rock

基于非线性波动方程和岩石节理非线性变形特性,建立一维非线性纵波法向入射单一节理的透射波计算理论.对节理、波源、岩石非线性系数和节理位置进行参数研究,探讨节理非线性变形对非线性波波形、透射系数和频率分布的影响.研究结果表明,非线性波传过节理后透射波振幅衰减,持续时间增长,节理初始刚度越小,波源的频率和振幅越大,该现象越明显.透射系数随节理距波源距离的增大而减小,振幅和频率越大的非线性波的透射系数减小的越快.节理距波源距离增大到一定值后,振幅越大的非线性波的透射系数越小,该距离的大小与波源参数有关.透射波中会产生一系列高频波,这些高谐波是在节理和岩石的共同作用下产生的.

In this paper, a computational theory was proposed on the one-dimensional nonlinear P-wave across single joint. The theory was based on the nonlinear wave equation and nonlinear displacement discontinuity normal deformation behavior of rock joint （BB model）. By varying the parameters of joint number, wave source, nonlinearity of rock and joint location, the study was focused on the effects of joint nonlinearity on the waveform, transmission coefficient and frequency spectra of nonlinear waves. For nonlinear waves, an attenuation of amplitude and a growth of duration for the transmission wave were found after the joint in this study. This phenomenon was more evidential with smaller initial normal stiffness of joint, bigger amplitude of P-wave, and higher frequency of P-wave. The transmission coefficient decreased when the distance between joint and wave source increased. And the decreasing rate of transmission coefficient accelerated with the raise of the amplitude and frequency of P-wave. When the distance between joint and wave source has reached a certain value,for the P-wave with bigger amplitude, the transmission coefficient is smaller. And this distance is in related to the wave source. The result also showed that a series of higher harmonics were generated in transmitted wave, which were caused by the interaction of rock and joint.