• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1522-1529
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• 2009

When a shaft is excavated in Korea, the mechanized method such as RBM(Raise Boring Machine) or RC(Raise Climber) is used independently of depth. But usually, the mechanized method is useful for the deep depth. On the contrary, when the depth of shaft is short, the cost of excavation increase. So in the case of shaft constructon less than 100m, we need to consider more suitable method of shaft construction such as Stage-cut which is one of blasting methods. Stage-Cut is widely used in the field of shaft construction in Japan as a tool of rock excavation. The main purpose of this study is to provide technical guidance for design and construction of shafts in rock, using Stage-cut method which is suitable for 20m~80m depth shaft. In this study, Blasting tests was performed in field, according to rock classification. Finally, the stage-cut method which is suitable for the geology of Korea was developed.

• Explosives and Blasting
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• v.10 no.3
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• pp.8-25
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• 1992

On the Sub- way Construction It is important to Survey in advance the Geological Structure and also to make the Engineering Geological map this paper deseribs the feature of Geological structure of Seoul Area and analyses the recently occured Rock falling acciudents. NATM Tunnelling always must be done with careful observation and measurement of the geological condition.

• Explosives and Blasting
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• v.8 no.1
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• pp.3-16
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• 1990

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill $\varphi{70mm}$ on the calcalious sand stone(sort-moderate-semi hard Rock). The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites (m) W : Maximum Charge per delay-period of eighit milliseconds or more(Kg) K : Ground transmission constant, empirically determind on th Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity $D/W^b$ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three graups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge per delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m----under l00m----- $V=41(D/3\sqrt{W})^{-1.41}$ -----A Over l00m-----$V= 121(D/3\sqrt{W})^{-1.66}$-----B K value on the above equation has to be more specified for furthur understang about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Explosives and Blasting
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• v.9 no.4
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• pp.3-12
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• 1991

The cautious blasting works had been used with emulsion explosion electric M /S delay caps. Drill depth was from 3m to 6m with Crawler Drill 70mm on the calcalious sand stone (soft-moderate-semi hard Rock) . The total numbers of feet blast were 88. Scale distance were induces 15.52-60.32. It was applied to Propagation Law in blasting vibration as follows .Propagtion Law in Blasting Vibration V=k(D/W/sup b/)/sup n/ where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W ; Maximum Charge per delay -period of eight milliseconds or more(Kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents Where the quantity D/W/sup b/ is known as the Scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagrorized in three groups. Cabic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge delay Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom and over loom distance because the frequency is varified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m--under 100m----V=41(D/ W)/sup -1.41/-----A Over l00m---------V=121(D/ W)/sup -1.56/-----B K value on the above equation has to be more specified for furthur understand about the effect of explosives. Rock strength, And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Explosives and Blasting
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• v.28 no.2
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• pp.133-147
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• 2010

A Suggestion of In-situ Rock Mass Evaluation and Correlation between Rock Mass Classfication MethodsThe purpose of this study is to find out rock mass classification method which is practically applicable to a field and to consider a correlation between the new method and the old method. Rock mass is an aggregate of separated blocks. To express the aggregate, the properties of both intact rock and rock mass should be considered. In this study, therefore, parameters for rock mass description are classified into rock strength and rock structure. Indices for parameters evaluation are obtained from old method and the strength and structure property of rock is described by using those indices. Value of 25 is allocated to each parameter obtained. $RMR_{basic}$ =0.86(X=Method)+14.47 is derived between $RMR_{basic}$ and this study and $RMR^*$ = 0.87(X-Method)+9.20 is derived between revised RMR and this study. Coefficient of determination is $R^2$=0.841 and $R^2$=0.846 each.

• Explosives and Blasting
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• v.8 no.4
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• pp.3-22
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• 1990

The $\varphi{4.5}$ meters pilot tunneling work is almost done to the $\varphi{11.3}$ meters twin tunnel of NAM SAN No1. The south side pit of 400 meters is weak zone of Rock status, so client request us to allow the cautious blasting pattern for drilling on the condition of 0.2 kine vibration allowance limited for the safety of side running tunnel. The pattern of cautious blasting carried out by 6 time divided fiving on the round drilling depth of 1.20 meters(1.10) and also applied control blasting method with line drilling due to the reduction of vibration.

• Explosives and Blasting
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• v.18 no.1
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• pp.59-70
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• 2000

The blasting work to construct a subway in seoul, korea have often cased increased neighbor＇s complaints because of ground vibration. In order to prevent the demage to the stucture it was necessary to predict the level of blasting induced vibration and to determine the maximum charge weigh per delay with an allowable vibration level. The effect of blasting pattem, rock strength and different explosive on the blast-induced ground vibration was studied to determine the maximum charage weight per delay within a given vibration level. The blasting vibration equation from over 100 test data was obtained, V= K(D/W(equation omitted), where the values for n and K are estimated to be 1.7 to 1.5 and 48 to 138 respectively.

• Explosives and Blasting
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• v.8 no.3
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• pp.3-13
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• 1990

First ot of all, under given condition such as bit gage of 36mm Drill bit with right class of jack-leg-experimental test carried out from two face of Bench, firing of each hole brought 90 degree Angle face and them measured length of Burden and charged ammount of powder as following. $ca=\frac{A}{SW}$ A=Activated Area A=nd i=m S=Peripheral length of charged, room Ca=Rock Coeffiecency d: di=Hole diameter When constructed subway of Seoul in 1980 the blasting works increased complaint of ground vibration, in order to prevent the damage to structures. Some empirical equations were made as follows on condition with Jackleg Drill (Bit Gage 36mm) and within 30 meter distance between blasting site and structures. $V=K(D/W)^{-n}$ N=1.60 - 1.78 K= 48 - 138 Project is one of contineous works to above a determination of empirical equation on the cautious blasting vibration with Crawler Drill (70-75mm) in long distance. $V=41(D/\sqrt[3]{W})^{-1.41}$ $30m\le{D}\le{100m}$ $V=124(D/\sqrt[3]{W})^{-1.66}$ $100m\le{D}\le{285m}$.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.657-664
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• 2002

This study presents the influence of blasting-induced vibration on the adjacent structures in rocks of various RMR values. 3D finite element analysis was performed to simulate the behaviour of tunnel and adjacent structures during rock excavation. The blast loadings were evaluated from the blasting pressure which is depending on the type and amount of explosive charges. Influencing factors for the stability of adjacent structures and ground conditions were reviewed in terms of structural dimensions and RMR values. The stiffness and load of adjacent structures are modeled in the numerical analysis to Investigate blasting effects of the size of adjacent structures. The vibration velocity and maximum particle velocity was increase sharply when the RMR value changed from 30 to 50. The effect of particle velocity was minimized at the width of structure become 2 times of tunnel diameter.

• Explosives and Blasting
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• v.36 no.1
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• pp.34-38
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• 2018

It proceed the trial test by applying blasting system with combination of electronic detonator and non-electric detonator(Supex Blasting Method) for the purpose of preventing the over-break as well as controling the blasting vibration and noisy at the site of Boseong-Imseongri railroad section ${\bigcirc}{\bigcirc}$. As a result of that, the blasting vibration and noisy was measured within the allowable standard of vibration. In conclusion, the combination of electronic detonator and non-electric detonator can not only reduce come construction cost, level of vibration and noisy but also get the prevention effect for Public resentment and minimize the rock-damage through over break control.