- 學位論文
爆破衝擊下的岩石破裂過程之高速影像分析
HIgh-Speed Image Analysis of the Rock Fracture Process under the Impact of Blasting
摘要
良好的爆破效果一直都是從事爆破的工程人員和研究人員所追求的。然而，由於爆破歷時短、功率大等原因，人們很難清楚地認識爆破過程並控制好爆破效果。高速攝影技術為研究炸藥爆轟理論、岩石爆破破碎機理、確定爆破最佳爆破參數、分析爆破效果等提供了很有意義的科學依據。 本研究經不斷嘗試與修正，終於完成以每秒約3萬張（每張間格約32μs，曝光時間4μs）之高速攝影拍攝爆破試驗數次，拍攝所得提供了一些可以觀察岩體在爆破衝擊下其裂隙產生、發展及其衰減程度及氣體膨脹壓力場與原岩應力作用下之破壞過程之清晰影像。經觀測結果發現爆破後之氣體膨脹率約於200μs時達到最大值，之後即逐漸衰減；至於爆破後岩體碎裂之發展速率，約於130μs達到最大值，此時也是二次裂紋發展之初期。而其後之衰減速率較為平緩，符合現代岩石爆破損傷斷裂理論之推論。惟因炸藥爆炸是一個物質的化學反應過程，其反應過程所需耗費之時間未能確定，導致爆破之起始時間無法確定。 本研究在爆破與攝影之同步作業上，亦控制不良，故觀測結果，僅能依據震波到達表面時之細微變化及裂紋呈現來推算，涉及主觀判斷。要克服這個盲點，尚須大量實驗來解決。另因岩石爆破之過程屬三維空間的破壞，而高速攝影僅能提供岩體破壞過程之表面現象，故對這種非常複雜而困難的爆破機制理論研究，仍有其侷限性。
並列摘要
The good blasting effect has always been pursued by engineering personnel and researchers engaged in blasting. However, due to the short duration of blasting, high power, and other reasons, it is difficult to clearly understand the blasting process and control the blasting effect. High-speed photography provides a meaningful scientific basis for studying the explosives detonation theory and rock blasting fracture mechanism, determining the best blast parameters of blasting, and analyzing the blast effect. After continuous trials and correction, this study finally completed the high-speed photographical shots of approximately 30,000 (each grid was about 32μs, and exposure time was 4μs) frames per second several times in the blasting tests. The clear images showed the generation, development, and decay extent of fissures of rock under the impact of blasting, the failure process under the gas expansion pressure field, and the original rock stress. Observations found that the gas expansion rate after the blast reached the maximum at about 200μs, and after that gradually decayed; as for the rock fracture development rate after blasting, it reached the maximum at about 130μs, which is also the early period of the secondary crack development, while the subsequent decay rate was relatively flat, in line with the inference of modern rock blasting failure and fracture theory. However, as the detonation of an explosive is a chemical reaction process that requires an undetermined amount of time, the start time of the blast cannot be determined. This study in the synchronous operation of the blasting and photography also had a poor control. So, the observations can only be calculated based on subtle changes when the shock wave reached the surface, and the presence of cracks, involving subjective judgment. To overcome this blind spot, a large number of experiments must be done. Also, as the rock blasting process is due to the failure of three-dimensional space, and the high-speed photography can only provide a surface phenomenon of the failure process of rock mass, the theoretical research on this complex and difficult blasting mechanism still has its limitations.