承受應力狀態下硬頁岩之超音波及聲射行為

Abstract

本研究嘗試利用自行設計之超音波探頭進行單軸直接拉力試驗及單軸 壓力試驗，以探討橫向等向性岩石在不同應力狀態下，動彈性模數的變化 。實驗的結果顯示單軸應力狀態下（單壓或單拉），彈性對稱面間裂縫閉 合與否，主要引起靜彈性係數的變化；材料分子結構因應力趨於緊密或鬆 散主要影響動彈性係數的變化。 此外藉著最佳化程式快速、反覆、正 確的運算，配合構造地質學上真傾角與視傾角的關係，以一個橫向等向性 岩石之圓柱試體，求取動彈性係數已不限於使用特殊傾角及入射角。 另外藉著聲射試驗，或者由電子式應變計所得到的靜彈性係數，都顯示出 單壓在10 MPa內就已經完成裂縫閉合，在接下來的更大應力階段□，所有 的靜彈性係數會趨於平穩，直到破壞前才會有強烈的變化。聲射事件在此 反覆的應力中，顯示出異向性岩石依然具有Kaiser效應，且此聲射事件具 有方向性。 In order to investigate the variation of dynamatic elastic constantsand the static elastic moduli of a transversely isotropic rock under loadings,a series of uniaxial tensil tests and uniaxial compression tests was conducted on the cylindrical specimens of argillite. The results show that the variation of the static elastic moduli during loading depends on the degree of closing of the pre-existing micro fissures along the folliations,but the dynamatic elasticconstants are little affected by that,which are strongly varied with the magnitude od applied stress on the grains of the rock. For obtaining the five dynamatic elastic constants of a transversely isotropic rock from a cylinderical specimens with inclined folliations ,a exact solution is given and a testing method is recommended in the thesis. For increasing the accurace of the suggested method ,an optimization technique is adapted fordata processing. Additionally,acoustic emission was measured during uniaxial compression test .It was found that the Kaiser effect was clear and the acoustic emission was anisotropic for the argillite specimens.