開發同步化聲光非破壞檢測於類岩材料受雙刀式貫切破壞之研析

A Study of Indentation Fracture in Rock-like Material under Doubled-indenters Associated with Synchronization of Acoustic and Optic Nondestructive Techniques

金昆翰(Kun-Han Chin)

指導教授 ： 陳立憲

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00259

摘要

因台灣地質構造變異性大，於隧道開挖時遭遇破裂帶、節理及斷層等不連續弱面之機率加大。又審視機械式鑽掘機開鑿隧道案例眾多，旨在提升工程自動化與安全性之考量，惟就其機械開挖之施工效率，仍待相關學理佐助，方得窺其工程進度之良窳，故本文乃由雙刀式機械開挖之影響進行評估，冀對開挖效能作適確的評估，以增進鑽掘切削岩體之破壞機制之理析。調查重點為變化楔刀間距因雙刀效應之影響，造成岩體接觸破壞之不同變形與力量(或能量)的區判，藉以評核鑽掘機械開挖效率之良窳。
本研究乃由工程鑽掘之多刀楔切削斷面，簡化模擬為雙刀楔之正向貫壓。而受壓材則採用水泥砂漿之類岩材料，在瞭解貫切相關之破壞機理下，於無側壓方式變化兩刀距但能同時接觸完整岩材(intact rock)之狀態，探討機械開挖之功效。本實驗研究試以巨觀和微觀之裂縫發展前、後，及其對應之力學特徵作一關照詮釋，其在可調整兩楔形刀口間距之貫壓位置下，採用裂縫開口位移(COD)控制求得完整之加載歷程，以進行破壞演化之觀察。而本研究所使用之觀察工具之一為非破壞聲射(AE)檢驗以量測微震裂源之定位，並同步控制電子點紋干涉術(ESPI)之破壞特徵，於自行開發之自動化同步擷取動態之聲、光兩非破壞檢測數據，以佐助貫切破壞試驗之定量觀測。
自動控制乃採NI公司之LabVIEW軟體，作為同步化(Synchronization)整合介面，先對聲光非破壞檢測與破壞性試驗之時序(time series)資料作比對而取得所需數據作為研究分析。經擷取程式時間同步處理後，將非破壞聲射法之微震裂源定位，與電子點紋干涉術之外部破壞特徵觀察結果比對以評定延性破壞的彈-塑性區；和脆性破壞的峰前變形不連續(Displacement Discontinuous)之生、衍演化暨裂尖微塑區發展，再與相關離散元素法及有限元素法之數值解析作一驗證。首次得到自動同步化聲射與光電干涉之非破壞檢測技術之適確結果。

關鍵字

雙刀效應 ； 聲射 ； 電子點紋干涉術 ； 同步化 ； 裂縫開口位移

並列摘要

Because of the high geologic structure changeability in Taiwan, some underground excavating difficulties such as meeting the fissuring zone, jointed rock mass and fault may raise frequently. The mechanical tunnel excavation, therefore, becomes important for concerning its advantages of automatic efficiency and construction safety. However, the mechanism of cutting process or so-called contact mechanics is not quite clear so far. To evaluate the cutting efficiency in the viewpoint of force and energy required to break rock, this paper hence presents the mechanical cutting effect of doubled-indenters on indentation-typed excavation by varying the space between indenter to indenter, . Meanwhile, coupled nondestructive techniques of acoustic emission (AE) as well as electronic speckle pattern interferometry (ESPI) are synchronized to monitor the evolution of fracture automatically during the normal wedge indentation tests in rock-like, quasi-brittle material.
By controlling the feedback signals of the crack opening displacement (COD) in a closed-loop hydraulic loading system, the entire loading curve can then be carried out in cement mortar. The experimental results show the microscopic evolution of ductile failure followed by brittle fracture in real-time, whole-field, high resolution from ESPI images corresponding to the locations of microseismic sources from AE. Furthermore, both the displacement continuity and displacement discontinuity, which are not identical to pre- and post-peak, can then be identified. In other words, both (1). the development of plastic zone and localization of the microcracking growth at the stage of ductile failure, and (2). the onset of crack evolved from the localization and crack propagation at the stage of brittle failure can be examined respectively. Note that the programming to synchronize both data of ESPI and AE is written in LabView 8.0 software in the laboratory. This is the first automatic synchronization of coupled ESPI and AE nondestructive techniques.
Finally, this study summarizes the value of critical space ( ), critical elastoplastic interface, and crack initiation/propagation experimentally, which are reasonable and agreeable by comparing with numerical simulation of coupled distinct element (PFC2D) and finite element method (FLAC).

並列關鍵字

Effect of double wedge-shaped edge ； Acoustic emission ； Electronic speckle pattern interferometry ； Synchronization ； Crack opening displacement

參考文獻

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