弹性波在含双裂纹岩体中的传播分析

Analysis of propagation of elastic wave in rocks with double-crack model

岩石和岩体是具有复杂细微观结构的非均匀介质.弹性波在岩体中传播时,与岩体细微观缺陷相互作用表现出弹性波的频散效应.为研究岩体内部细观结构对弹性波频散效应的作用,本文采用双裂纹模型:在模型内部,考虑裂纹间的相互作用对弹性波的影响,以分析弹性波在双裂纹体系间的多次散射作用;在双裂纹体系间,采用线性叠加分析法,以考虑岩体缺陷影响的局部化.对波动方程应用Green函数基本解,利用边界积分方法,将双裂纹体系作为内边界处理,得到相应的频散方程,由此对比分析了双裂纹体系在上述两种分析方法下的区别,进一步探讨了双裂纹体系参数、孔隙流体压力和卸荷对岩体频散特性的影响.

Rock and rock mass are non-homogeneous medium with complex micro-and meso-scopic structures.Dispersion effect results from the interaction between the elastic wave and these micro and meso defects in rocks.A double-crack model is proposed to study the effect of microscopic structures on the dispersion of elastic wave.In the model,the interaction between these two cracks is accounted for to partly consider the effect of multiple scattering.Among these double-crack systems,linear superposition method is adopted to analyze the localization effect of defects in rocks.Specifically,based on the fundamental solution of Green function to wave propagation equation,and combined with the boundary integral method,cracks are treated as inner boundaries and the dispersion equation is obtained.Furthermore,the difference between these two ways of interaction of cracks is analyzed,and the influence of the micro discontinuity parameters of the double-crack system,pore fluid pressure and unloading on the dispersion of rocks is discussed.