Conference Paper 3次元動的破壊プロセス解析法を用いた岩石の動的引張試験に関する基礎的検討

二瓶, 恵理菜  ,  福田, 大祐  ,  Cho, Sang-Ho  ,  Oh, Se-Wook  ,  児玉, 淳一  ,  藤井, 義明

Description
岩石の動的引張強度を求めるために,ホプキンソン効果による剥離現象を用いた動的引張試験が度々行われてきている.本試験では,これまで円柱状の岩石供試体の自由端変位速度の経時変化や主破断面位置を基にした種々の強度算定法が提案されているが,現在も最終的な結論に至っていないと思われる.本試験の理論検証を行うためには,上記の主破断面位置や岩石供試体の自由端変位速度の計測結果をシミュレート可能なツールが必要となるが,現実的に岩石の3次元動的破壊プロセスを解析可能なツールはこれまで限られていた.本稿では,Geochang花崗岩の動的引張試験を対象として,著者らが最近開発した岩石の3次元動的破壊プロセス解析法を適用することで,実験から得られた供試体の自由端変位速度や破砕形態等を良く表現可能であることを明らかにし,提案した解析法が岩石の動的引張強度の算出法に関するより詳細な議論を行うための有用なツールであることを示す.
Evaluation of dynamic tensile strength of rock is of a significant importance for blasting design in terms of such as blasting−induced damages and fragmentation of rock. Dynamic tension test based on Hopkinson effect combining with spall phenomena has been performed to determine dynamic tensile strength of rock by various researchers. However, they have proposed different evaluation methods for dynamic tensile strength using such as free surface velocity, positions of fracture plane and elastic wave velocity of the cylindrical rock specimen based on different hypotheses while have not reached a definitive conclusion. In addition, verification of each evaluation method is very challenging since the number of useful tools which can analyze the 3−dimensional(3−D) dynamic fracture process of rock have been limited. To overcome this situation, we have developed a 3−D Dynamic Fracture Process Analysis (DFPA) method which can realistically simulate the complex 3−D fracturing process of rock. In this paper, we applied the 3−D DFPA method to the dynamic tension test. The results show that the DFPA can express the free surface velocity, positions and patterns of fracture measured by experiments and could be a useful tool to discuss about each evaluation method in greater detail.
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http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/64320/1/JSRM2017.32.pdf

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