脆性岩石受載過程之聲射特性與定位

Abstract

脆性岩石在受載的過程中，材料內部原生裂縫尖端可能有應力集中的現象 ，以致造成裂縫的延伸。隨著載重的增大，裂縫間可能相互連結，終至形 成一主要裂面導致崩潰破壞。這些裂縫的啟動、成長所產生之彈性應力波 ，極易為聲射擷取系統所接收、記錄。本研究即希望藉助聲射量測技術來 探討受載脆性岩石中裂隙之發展，同時分析不同載重條件下 (單軸壓縮試 驗、三點載重試驗、巴西間接張力試驗) 聲射訊號之特性。經由本研究試 驗結果之分析，得到以下的結論： 1.以聲射定位來探討脆性岩石受載過 程中裂隙之發展，具有其可行性。 2.由變質石英砂岩三種試驗結果，歸 納聲射數比與振幅、歷時、能量的關係，可發現具有一致性的相對大小關 係。 3.脆性岩石在受載過程中，高振幅聲射訊號的出現與裂縫的不穩定 成長之間，存在密切的關係。 4.利用聲射技術可有效分辨岩石不同的受 載階段。 The microfractures in a brittle rock may develop or expand when the material is subjected to loading. Microfracturing process in the material will result in elastic waves,which can be detected by an acoustic emission data acquisition system. This thesis aims to investigate the acoustic emission characteristics and the fracturing process under various loading condition (uniaxial compression test, three-point- bending test , Brazilian test ). Conclusions are drawn from the study： 1.It seems feasible to use acoustic emission source location technique to investigate the crack developing process of a brittle rock Subjected to loading. 2.For the sample used in the study, it is found that the relative order of the amplitude ,duration ,energy level of acoustic emissions occur in various loading types are all similar. 3.In general, acoustic emission of the highest amplitude tends to occurs in the stage of unstable crack propagation. 4.Different loading stages can be identified effectively by the acoustic emission technique.