两条粗糙平行节理构型对超声波波速影响的试验研究  

Experimental Study on the Influence of Two Rough Parallel Joint Configurations on Ultrasonic Wave Velocity

作　　者：李业学[1,2] 徐福卫[1] 马彦熊 周伟[1] 

机构地区：[1]湖北文理学院,湖北襄阳410053 [2]四川大学,四川成都610065 [3]南洋理工大学,新加坡639798

出　　处：《实验力学》2017年第6期818-826,共9页Journal of Experimental Mechanics

基　　金：湖北省教育厅科学技术研究计划重点项目(D20142603)

摘　　要：基于图形图像学和分形几何学交叉学科理论,采用图像学中的颜色单元体,借鉴将颜色灰度值间接对应节理面高度值的思想,结合分形布朗函数,本文提出了间接描述节理粗糙度的自仿射维数计算方法——YUV维数法。依据本文提出的方法,计算了24个节理岩石共48个粗糙面的YUV维数,剖析了节理面几何构型的分形特征。采用含两条节理岩石超声波试验,探讨了节理岩石的两条节理YUV维数对超声波波速的影响规律。研究结果表明,超声波波速平均值随着任一节理YUV维数、两条节理维数之和减小而增大。在维数减小过程中,尽管波速持续增加,但波速增大速率逐渐降低。当维数减小至某个量值时,波速不再增大,近似趋于一常量。通过类比分析,文中认为上述结论的机理和原因是:维数由大变小的过程,可类比为节理面孔隙缺陷被逐渐压密且分布越来越规则的过程,因为在此过程中,量化的数值体现就是维数逐渐变小。因而,当维数变小,或者说节理面缺陷孔隙被压密且分布更为规则时,超声波波速将由小变大,且最后将趋于一常数。Based on the interdisciplinary theory of graphics,iconography and fractal geometry,adopting colour unit from iconography,drawing on the idea that colour gray value is indirectly corresponded to joint surface height,combining fractal Brown function,a method for calculating selfaffine dimension for indirectly describing joint roughness-YUV dimension is presented in this paper.Based on above mentioned method,the YUV dimensions of 48 rough surfaces taken from 24 jointed rocks were calculated and fractal characteristics of joined surface geometric configuration were analyzed.Based on ultrasonic experiment of rock sample with two joints,the influence of YUV dimension of two joints on ultrasonic wave velocity was discussed.Study results show that the mean value of ultrasonic wave velocity increases not only with the decrease of any single joint YUV dimensions,but also with the decrease of the sum of two joints YUV dimensions.During the process of dimension decreasing,although the wave speed continuously increases,but the increasing rate gradually decreases.When the dimension is reduced to a certain value,wave speed does not increase further and approximately approaches to a constant.Through comparison analysis,the mechanism and cause of above conclusion are explored.The process of dimension change from large to small can be compared with the process that the pore defect of joint surface is gradually compressed and distributed more and more regularly.In this process,the numerical representation of quantization is just the dimension number decrease.So,when dimension decreases,the pore defect of joint surface is gradually compressed and distributed more and more regularly,which results in the increase of ultrasonic wave speed and approaching to a constant.

关 键 词：节理岩石 超声波 波速 分形 几何构型 

分 类 号：TU457[建筑科学—岩土工程]