• Title/Summary/Keyword: 누두공

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Study on the Classification of Weak Rock by Test Blast (시험발파에 의한 연약암반 평가에 대한 연구)

  • 선우춘;전양수;천대성;한공창
    • Explosives and Blasting
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    • v.21 no.4
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    • pp.1-10
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    • 2003
  • The classification of weak rocks is normally connected with the rippability classifications. The excavation of rock is frequently carried out by blasting. A classification of the weak rocks by test blasting with small quantity of explosives was attempted in the present study. The crater ratio and blasting constant that resoled from test blasting were used as a e parameter of the classification. The seismic velocity of rock mass and Protodyakonov's index were also applied for the also rock classification.

Tunnel Blasting Design with Equations Obtained from Borehole and Crater Blasting (시추공 및 누두공 발파자료의 터널설계 적용)

  • 양형식;임성식;김원범
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.327-333
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    • 2003
  • Characteristics of vibration propagation of borehole blasting were analyzed with 578 borehole vibration data obtained from 23 sites which were used in tunnel and underground space design, and 221 tunnel vibration data fron 4 sites of tunnel under construction. Analysis results on the damping of vibration velocity show that site factors in borehole blasting were higher than those in tunnel blasting. And the critical charge calculated from regression equations at large scaled distance was lower in borehole blasting. Dominant frequency was in the range of 30∼60Hz for the borehole blasting and 60∼90Hz for the tunnel blasting. As a conclusion, the borehole blasting data should not be used on the tunnel blasting design without careful statistical analysis.

An Experimental and Numerical Study on the Stemming Effect of a Polymer Gel in Explosive Blasting (화약발파에서 폴리머 겔의 전색효과에 관한 실험적 및 수치해석적 연구)

  • Baluch, Khaqan;Kim, Jung-Gyu;Ko, Young-Hun;Kim, Seung-Jun;Jung, Seung-Won;Yang, Hyung-Sik;Kim, Youg-Kye;Kim, Jong-Gwan
    • Explosives and Blasting
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    • v.36 no.4
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    • pp.35-47
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    • 2018
  • In this study, several concrete-block blast tests and AUTODYN numerical analyses were conducted to analyze the effects of different stemming and coupling materials on explosion results. Air, sand, and polymer gel were used as both the stemming and coupling materials. The stemming and coupling effects of these materials were compared with those of the full-charge condition. Soil-covered or buried concrete blocks were used for field crater tests. It was found from the concrete block tests and numerical analyses that both the crater size and the peak pressure around the blast hole were higher when the polymer gel was used than when the sand and the decoupling condition were used. The numerical analyses revealed the same trend as those of the field tests. Pressure peaks in concrete block models were calculated to be 37, 30, and 16 MPa, respectively, for the cases of the polymer gel, sand, and no stemming and decoupling condition. The pressure peak was 52 MPa in the case of full-charge condition, which was the highest pressure. But the damage area for the case was smaller than that obtained from the use of polymer gel. Full-charge was also used as a reference test.