Dynamical study on the blasting with one-free-face to utilize AN-FO explosives : 硝油爆藥類를 活用한 單一自由面發波의 力學的 硏究

국문 초록 (Abstract)

發破에 있어서 穿孔配置는 發破效果에 影響을 미치는 가장 重要 한 要素中의 하나이다. Burn Cut의 爆發의 여러 要素에 關한 硏究는 Brown, Cook等에 依해 發表된 바 있으나 本 硏究에 있어서는 Burn-Cut와 Pyramid-Cut의 穿孔配置의 對比와 爆源과 自由面 사이의 力學的 應力 解析에 重點을 두어 伊勝 敎援가 展開한 理論에서 다루지 않은 適正穿孔配置에 依한 Burn-Gut의 效果를 連結시켰다.
從來의 理論에 依하면 .準- 自由面 發破에 있어서는 壓縮應力外 에 自由面에서 反射되는 引張應力의 影響을 追加로 받는바 本 新穿孔 配置에 依한 Burn-Cut는 自由面數의 增加와 距離의 縮小를 피하므로 이 效果는 더욱 增大된다.
이와 같은 效果를 爲해서는 다음 두가지 点을 考慮해야 한다.
첫째 心技孔의 無裝藁孔은 補助應力을 크게 하기 爲해해 可能한 大口徑으로 깊게 穿孔해야 한다.
둘째 각 心技孔間의 距離를 接近시켜 完全 發破를 期해야 한다. 그 까닭은 口徑이 增加됨에 따라 2次 自由面은 넓어지고 거리가 가까울수록 製藥孔과 無製藥孔 사이의 引張應力은 더욱 發達되기 때문이다. 先進國에서는 心□孔사이의 距離를 4 "로. 함이 理想的 이라고 알려지고 있으나 本實驗에 依하면 더욱 近接될수록 破壞巖石이 增加되고 掘進長도 깊어짐이 밝혀졌다. 나아가서는 掘進長을 더욱 增大시키기 爲해 Burn-Cut로 부터 large hole Burn-Gut를 開發하여 發破回數 max 7回/日로서 1發破堂 3.1 m까지 試圖 함으로서 高速度掘進의 起源을 마련했다.
또한 大口徑 Burn-Cut에서는 큰 抵抗을 극복하기 위해 金□硝 油爆藥을 使用함이 더욱 效果的임이 立證�榮�
最初 低廉한 □格과 取扱安全으로 각광을 시작한 AN-FO는 비료용 또는 産業用 硝安에 燃料油를 混合한 것으로서 雷管의 起爆前 에는 鈍感하나 Gelatine Dynamite 等의 瀑發性 銳感劑에 依해 發破孔內에서 일단 起爆되면 從來의 硝安爆藥에 相當한 威力을 發揮한다. AN-FO 爆劑의 性能에 關해서는 많은 報告가 있었으나 本 實驗에 依하면 硝油混合比는 粉狀은 93.5 : 6,5 . Prill狀은 94 : 6이 最適이며 粉狀 An-FO는 Prill 狀 AN-FO보다 恒常 爆速이 높다.
또한 起爆感度 ,衝擊感度.,摩擦感度 等 諸感度는 他火藥에 比해 몸시 鈍感하며 傳爆性을 Prill 狀이 粉狀보다 優秀함을 얻었다. 發破後 Gas도 良好하며 AN-PO는 製造後 7日 前後가 最大 效果를 갖는다.
從來 AN-FO는 지난 여러해 동안 露天掘에만 使用하여 왔으나 筆者는 AN-FO의 基礎性能試驗을 土台로 이를 利用한 新種爆劑로서 金屬硝油爆藥과 水中爆藥을 發展시켰다.
金屬硝油의 爆藥은 AN-FO와 A1 金屬粉末의 混合物이며 水中爆藥은 從來爆藥과 AN-FO로 製造한 바 이에 關해서는 附錄에 記述 했다.
本 硏究에 있어서는 單一自由面 發破에 있어서 硝油爆藥類를 活用한 바 그 效果가 매우 良好하였음을 確認하였다.

다국어 초록 (Multilingual Abstract)

Drilling position is one of the most important factors affecting on the blasting effects. There has been many reports on several blasting factors of burn-cut by Messrs. Brown and cook, but in this study the author tried to compare drilling positions of burn-cut with pyramid-cut, and also to correlate burn-cut effects of drilling patterns, not being dealt by prof. Ito in his theory, which emphasized on dynamical stress analysis between explosion and free face.
According to former theories, there break out additional tensile stress reflected at the free face supplemented to primary compressive stress on the blasting with one-free-face. But with these experimented new drilling patterns of burn-cut, more free faces and nearer distance of each drilling holes make blasting effects greater than any other methods.
To promote the above explosive effect rationally, it has to be considered two important categories under-mentioned.
First, unloaded hole in the key holes should be drilled in wider diameter possibly so that it breaks out greater stress relief.
Second, possibly key holes should have closer distances each other to result clean blasting.
These two important factors derived from experiments with, theory of that the larger the dia. of the unloaded hole, it can be allowed wider secondary free faces and closes distances of each holes make more developed stress relief, between loaded and unloaded holes.
It was suggested that most ideal distance between holes is about 4˝ clearance in U.S.A., but the author, according to the experiments, it results that the less distance allow, the more effective blasting with increased broken rock volume and longer drifted length can be accomplished. Developed large hole burn-cut method aimed to increase drifting length technically under the above considerations, and progressive success resulted to achieve maximum 7 blasting cycles per day with 3.1m drifting length per cycle. This achievement originated high-speed-drifting works, and it was also proven that application of Metallic AN-FO in large hole burn-cut method overcomes resistance of one-free-face.
AN-FO which was favored with low price and safety handling is the mixture of the fertilizer or industrial Ammonium-Nitrate and fuel oil and it is also experienced that it shows insensible property before the initiation, but once it is initiated by the booster, it has equal explosive power of Ammonium Nitrate Explosive (ANE). There were many reports about AN-FO.
On AN-FO mixing ratio, according to these experiments, powdered AN-FO, 93.5:6.5 and prilled AN-FO, 94:6 are the best ratios. Detonation, shock, and friction sensitivities are all more insensitive than any other explosives. Residual gas is little toxic. On initiation and propagation of the detonation test, prilled AN-FO is more effective than powdered AN-FO. AN-FO has the best explosion power at 7 days elapsed after it has mixed.
While AN-FO was used at open pit in past years prior to other conditions, the author developed new improved explosives, Metallic AN-FO and Underwater explosive, based on the experiments of these fundamental characteristics by study on its usage utilizing AN-FO. Metallic AN-FO is the mixture of AN-FO and Al, Fe-Si powder, and Underwater explosive is made from usual explosive and AN-FO. The explanations about them are described in the appendix.
In this study, it is confirmed that the blasting effects of utilizinng AN-FO explosives are very good.

목차 (Table of Contents)

• CONTENTS
• 1. INTRODUCTION = 1
• 2. CHARACTERISTIC EXPERIMENT = 5
• 3. BLASTING EXPERIMENTS AND DRILLING PATTERNS = 24
• 4. DYNAMICAL STUDY ON ROCK BREAKAGE MECHANISM = 40
• 5. CONCLUSION = 56
• REFERENCES = 58
• APPENDIX = 60