石材裂紋擴展量測之研究

The Measurement of the Crack Propagation in Rock Slab

謝其泰(C.T. Hsies) ； 王建力(C.L. Wang)

《鑛冶：中國鑛冶工程學會會刊》 48卷2期 (2004/06) Pp. 165-175

https://doi.org/10.30069/MM.200406_48(2).0012

摘要

本研究建立一套試驗觀測系統專供岩石材料裂紋起裂與擴展之研究。試驗過程中以高速攝影機直接觀測岩石材料之裂紋起裂與擴展，同時利用裂縫應變片即時記錄系統求出試體之裂縫擴展速度。在不同之加載速率下，本研究分別探討花崗岩與大理岩試體裂紋尖端附近之裂紋擴展速度之分佈及其與斷裂性質間之關係。在本研究的設定條件下（加載速率範圍在0.5～100mm／min），試驗結果發現：1.花崗岩試體，裂紋擴展實測平均速度範圍約在0.67～325cm／sec；實測最大瞬時速度範圍約在12.6～2520cm／sec；斷裂韌性範圍約在1.96～3.59Mpa√m。2.大理岩試體，裂紋擴展實測平均速度範圍約在7.66～277cm／sec；實測最大瞬時速度範圍約在72.5～3360cm／sec；斷裂韌性範圍約在1.03～1.35MPa√m。斷裂韌性與裂紋擴展速度之關係，並無明顯的結果。此外，本研究發現大理岩較易受到邊界效應之影響，使裂紋之擴展偏移；裂紋擴展實測最大瞬時速度遠比理論極限裂紋擴展速度低。

關鍵字

岩石 ； 裂紋擴展 ； 高速攝影機

並列摘要

A WLCT (Wedge Loading Compact Tension) system was built in this study to investigate the phenomenon of crack propagation in rock slabs. The rock slabs under investigation were selected from natural building stones. Two samples were investigated: Dark Granite and White Marble. A high-speed video system was used to monitor the crack propagation, while a high-resolution crack-strain-gage system was used to measure the crack propagation velocity. In this study, the loading method was displacement-controlled and the loading rates were chosen in the range of 0.5 to 100 mm/min. This study finds: 1. For Dark Granite samples, the average crack velocity near the crack tip was measured in the range of 0.67 to 325 cm/sec; the maximum crack velocity near the crack tip was measured in the range of 12.6 to 2520 cm/sec; the fracture toughness is found to be 1.96 to 3.59MPa√m. 2. For White Marble samples, the average crack velocity near the crack tip was measured in the range of 7.66 to 277 cm/sec; the maximum crack velocity near the crack tip was measured in the range of 72.5 to 3360 cm/sec; the fracture toughness is found to be 1.03 to 1.35MPa√m. Experimental results from this study have not indicated that the crack velocity and the fracture toughness have a direct relationship for both samples. It is also found that White Marble shows a strong boundary effect and the resulting crack path could deviate. The measured crack velocity in this study is much lower than the theoretical upper bound of crack velocity.

並列關鍵字

Rock ； Crack Propagation ； High-Speed Video System