超音波儀器之組裝及異向性岩石之超音波特性

Abstract

為從事岩石之超音波特性研究，本研究組裝一部適合岩石檢測之超音波儀 器。並以壓電複合材料取代傳統之超音波探頭（如PZT等），經過一系列 測試，證明能用壓電複合材料取代一般之傳統探頭，來實施超音波檢測。 本研究利用波傳理論，建立一套新的實驗方法，克服必須由多個試體才能 求得異向性岩石動彈性模數之缺點。首先利用超音波的量測，建立圓柱試 體走向與傾角的判定模式，使實驗進行之前能更準確定出岩石的層面。然 後利用一個傾角為 的圓柱試體，經過超音波的量測，求取具橫向等向性 之乾溝層硬頁岩的五個動彈性模數，其動彈性模數分別為E=61.51（GPa ）,E'=36.20（GPa）,G=27.52（GPa）,G'=15.57（GPa）,v=0.113, v'=0.281。此動彈性模數比由靜態實驗所求出的彈性模數略高。 In order to study the property of the anisotropic rock , an ultrasonic testing equipment was assembled . After a series of testing ,it can be found that the piezoelectric film ,which can be used to replace the convention transducers material （such as PZT.. ）, is a good transducer material. A new method for determining the orientation of foliation planes（or schistosity ）of a cylindrical specimen is proposed by using ultrasonic technique . The strike of foliation planes is the direction of the maximum velocity measured on the plane perpendicular to the cylindrical axis of the specimen .The dip direction is that of maximum amplitude measure on the vertical plane normal to the strike . The orientation by the proposed method is accurate enough for rock testing . By the application of the theory of wave propagation for anisotropic rock , the formulations for obtaining five dynamic elastic modulus by one cylindrical specimen with the foliation (or schistosity）planes parallel to the long axis is derived. Based on the formulations ,the mean elastic constants of Ken-Guo argillite are calculated from the data of a series of ultrasonic test as follows ： E=61.51（GPa） ， E'=36.20（GPa），G=27.52（GPa）， G'=15.57（GPa）， =0.113， '=0.281 . The dynamic elastic constants are higher than the elastic constants by static experiment.