• Tunnel and Underground Space
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• v.20 no.4
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• pp.252-259
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• 2010

In urban tunnels, namely, in case there are residents in the near distance, we normally use non-vibration and ambient vibration which are not blasting methods because it’ impossible to meet the blasting vibration regulation with only normal explosives. However, non-vibration methods not only cause increase of excavating cost, but need much time than explosives. Generally, the lower velocity explosives with 2,000 m/s VOD have been applied to ambient vibration blasting in open cut area, but difficult in tunneling in its use. However, by charging the hole together with lower velocity explosives and normal explosives, we have got the result which shows 20~30% vibration decrease compared with using only normal explosives. Therefore, I’ like to suggest the blasting method which is able to do as ambient vibration using lower velocity explosives mixed with normal explosives in urban tunnel and the area which is adjacent to security facilities within the vibration regulation.

• Journal of the Korean Professional Engineers Association
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• v.24 no.6
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• pp.97-105
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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 ø70mm on the calcalious sand stone (soft-moderate-semi hard Rock). The total numbers of fire blast were 88 round. Scale distance were induces 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagation Law in Blasting Vibration (Equation omitted) where V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum Charge per delay-period of eighit milliseconds o. 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$^n$ 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. Cubic 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 100m distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30 ‥‥‥under 100m ‥‥‥V=41(D/$^3$√W)$\^$-1.41/ ‥‥‥A Over 100 ‥‥‥‥under 100m ‥‥‥V=121(D/$^3$√W)$\^$-1.56/ ‥‥‥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.

• Tunnel and Underground Space
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• v.19 no.5
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• pp.397-406
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• 2009

Recently, the number of industrial structures that must be demolished due to structural deterioration and unsatisfactory functional conditions has been increased. To minimize environmental hazardous factors created during the process of demolition, the explosive demolition method has been applied increasingly. This execution case was intended to describe an application of the explosive demolition method to the demolition of a Crusher & Screen structure, which was a large-section reinforced concrete special structure. It was deemed necessary due to its structural deterioration and unsatisfactory functional condition. Various pre-weakening processes and blasting patterns were applied to the large-section reinforced concrete members, and to reduce blasting vibration and impact vibration, time intervals were established for blasting in the same column and for blasting between blasting blocks. By applying the explosive demolition method to the demolition of a large-section reinforced concrete special structure, the explosive demolition was completed safely and efficiently, without causing any damage to surrounding facilities.

• Tunnel and Underground Space
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• v.7 no.2
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• pp.150-157
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• 1997

Various analytical, empirical and theoretical methods for slope stability assessment were applied on slopes to develop aggregate quarry optimally. Among them are block theory, stereographic analysis, RMR, SMR, limit equilibrium method and maximum likelihood. Test site was estimated that slopes were apt to fail although rock quality was good. Modified direction and dip angle was suggested for stability. To reduce the overbreak and to improve the stability, the vertical blasting was recommended for new subground level.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1999.03a
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• pp.41-50
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• 1999

발파는 토목, 건설현장이나 광산 등에서 암반에 대한 굴착 방법으로서 가장 널리 쓰이고 있는 방법중의 하나이다. 그러나 최근 들어 발파에 의한 진동이나 소음 등의 위해가 사회적 문제로까지 대두하고 있으며, 또한 발파작업에서 작업계획에 대한 결과의 정밀도를 높이기 위하여 조절발파 등 여러 가지 방법들이 연구 발전되어 가고 있는 추세에 있다. 이러한 연구들은 주로 현장 발파작업 및 발파패턴의 설계에 치중되어 있으며 발파모델을 이용한 해석 연구는 다소 미진한 정도이다. (중략)

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1999.03a
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• pp.51-54
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• 1999

현재 국내에서 시공되고 있는 터널 발파 패턴의 경우 현장암반조건과 발파조건 등 발파에 영향을 미치는 제반 여건을 정량적으로 고려한 컴퓨터에 의한 자동설계가 이루어지지 않고 있다. 그러므로 경험적이고 정성적인 방법에 의하여 터널 발파 설계가 이루어짐으로써 발파설계와 시공이 불일치하고 여굴 및 주변 손상권의 확대로 인한 터널 보강에도 영향을 미치는 등 문제점이 있다. 또한 최근에 들어와서 터널 발파 공사가 인가 근처에서 이루어 질 경우 발파진동에 의한 민원을 야기하고 있어 이를 고려한 안전 발파 설계가 절실히 요구되고 있다. (중략)

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.1
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• pp.25-40
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• 2004

The supersonic shock wave generated by fully coupled explosion will change into subsonic shock wave, plastic wave, and elastic wave consecutively as the wave propagates through rock mass. While the estimation of the blast-induced peak pressure was the main aim of the companion paper, this paper will concentrate on the estimation of the rise time of blast-induced pressure. The rise time can be expressed as a function of explosive density, isentropic exponent, detonation velocity, exponential coefficient of the peak pressure attenuation, dynamic yield stress, plastic wave velocity, elastic wave velocity, rock density, Hugoniot parameters, etc. Parametric analysis was performed to pinpoint the most influential parameter that affects the rise time and it was found that rock properties are more sensitive than explosive properties. The probabilistic distribution of the rise time is evaluated by the Rosenblueth'S point estimate method from the probabilistic distributions of explosive properties and rock properties. Numerical analysis was performed to figure out the effect of rock properties and explosive properties on the uncertainty of blast-induced vibration. Uncertainty analysis showed that uncertainty of rock properties constitutes the main portion of blast-induced vibration uncertainty rather than that of explosive properties. Numerical analysis also showed that the loading rate, which is the ratio of the peak blasting pressure to the rise time, is the main influential factor on blast-induced vibration. The loading rate is again more influenced by rock properties than by explosive properties.

• Explosives and Blasting
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• v.35 no.1
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• pp.18-26
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• 2017

In Analysis of Fragmentation of rock blasted, The photo analysis method has been mainly used and these image acquisitions are mainly obtained by digital image from the front of the crushed rock. However, Image analysis is basically advantage of the image of planar shooting not front shooting but There is no way to take a photograph of huge plane rock slope. Thus, Unavoidably It is resolved by distorting or extending the image filmed at the front as well as adjusting it similar to its angle of plane shooting. Lately, With advancing unmanned aerial vehicle, It can simply image the fragment conditions of blasted rock of a high-definition digital image and Through it, It can acquire the most planar image to angle which accumulate cataclastic rock and also can make image analysis. In this study, It has been confirmed that tolerance value of analysis result of image filmed flatly is markedly lower than the existing front filmed image.

• Tunnel and Underground Space
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• v.24 no.3
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• pp.187-200
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• 2014

After excavation or blasting, rock properties within an excavation damaged zone can be perpetually weakened on account of stress redistribution or blasting impact. In the present study, the excavation damaged zone is applied to a rock slope. The objective of this research is to compare the mechanical stability of the rock slope depending on the presence of the damaged zone using 2-dimensional modeling and analyze factors affecting factor-of-safety. From the modeling, it was founded that the mechanical stability of the rock slope is significantly dependent on the presence of the damaged zone. In particular, factor-of-safety with a consideration of the damaged zone decreased by approximately 49.4% in comparison with no damaged zone. Factor analysis by fractional factorial design was carried out on factor-of-safety. It showed that the key parameters affecting factor-of-safety are angle of the slope, cohesion, internal friction angle and height.

• Explosives and Blasting
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• v.24 no.1
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• pp.21-28
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• 2006

Rock mass classification systems such as RMR and Q system have been widely served as a simple empirical approach for the design of various rock mass structures in the stage of site survey as well as under the construction. For the RQD determination, the boring is partially carried out and what is more, the survey boring is not normally carried out under construction. Therefore RQD is frequently determined by empirical method or indirect method. Since it is difficult to determine the discontinuity characteristics such as RQD, spacing, persistence, filling and so on, it is essential to develop suitable and simple systems without drilled core and a cert 없 n number of representative parameters. One of the primary objectives of the classification systems for a practicing engineer has been to make it simple to use as a preliminary design tool for the structures in rock mass. In the present study, the modifications for both the RMR and GSI system are suggested by authors to introduce new classification system as well as to improve the scope of some of the existing classification systems for a practicing engineer.