• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.41-53
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• 2022

In the excavation work like blasting/excavator work bordering on the urban railway, the dynamic safety of railway structures like tunnel, open-cut box structure and elevated bridge was investigated by numerical analysis in this study. The practically presented criteria on influential zones at the blasting work in the construction industry was numerically checked in cases of the precise vibration-controlled blasting (type II) and the small scale vibration-controlled blasting (type III) and it was shown that the criteria on blasting work methods needed to be supplemented through continuous field tests and numerical analyses. The influence of excavation vibration by mechanical excavators was especially investigated in case of earth auger and breaker. The numerical analysis of tunnel shows that the criteria on vibration velocities from the regression analysis of field test values was conservative. The amplification phenomenon of excavating vibration velocity was shown passing through the backfilling soil between the earth auger and the open-cut box structure. It was shown that the added-vibration on the superstructure of elevated bridge was occurred at the bottom of pile like earthquake when the excavator vibration was arriving at the pile toe. The systematic and continuous research on the vibration effect from excavating works was needed for the safety of urban railway structures and nearby facilities.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.97-109
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• 2014

In order to identify the characteristics of the propagation depending on delay time (20, 25 ms) and priming location (top priming, middle priming, bottom priming), test blasts were carried out a total of 4 times using different spacing, burden, drilling length, charge per delay and was derived the formula to predict blast vibration. This study investigated the characteristics of vibration by analysis of the nomogram and prediction of Peak Particle Velocity (PPV) from delay time and priming location by the formula to predict ground vibration. And it analyzed the trends of vibration increase by standards charge 0.5, 1.6, 5, 15 kg. Standards charge is "Blasting design and construction guidelines to road construction" by the Ministry of Land, Infrastructure and Transport. Depending on the charge in favor of vibration control method is proposed. Thus, when the design was to be used as a variable.

• Explosives and Blasting
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• v.27 no.1
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• pp.38-46
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• 2009

Recently, as a reduction method of vibration and noise, an electronic detonation which has an accuracy of time and a freedom of input delay time was introduced. A waveform composition program can determine a delay time and accomplish simulation under environment similar to real blast using a delay time. In this study, optimum delay time which controls vibration is obtained and real measurement vibration level is estimated by a waveform composition program.

• Explosives and Blasting
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• v.27 no.2
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• pp.42-47
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• 2009

Ground vibrations caused by pile driving or explosive blasting can affect the stability of power line tower and its foundation. Because the characteristics of ground vibrations generally depend on the distances from the blast, the ground vibrations should be controlled by taking the distance into account. In this study, ground vibration levels were measured at the foundation of a power line tower and on ground surface adjacent to the tower. The relationships between the dominant frequencies of the ground vibrations that were measured at both locations were comparatively investigated.

• Explosives and Blasting
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• v.34 no.1
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• pp.11-18
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• 2016

It is necessary to minimize ground vibration and noise due to blasting work in urban environment. The blast induced ground vibration and noise are generally generated by a portion of detonation energy, where most of the energy is utilized for rock breakage and movement of rock mass. Recently a blast method utilizing U-shaped steel charge holder was suggested to reduce the ground vibration without decreasing destructive power toward the free surface. In this study, single hole blasting utilizing U-shaped steel charge holder were simulated and the stress waves caused by the detonation of explosives were monitored using AUTODYN software. In order to examine the fragmentation efficiency of the U-shaped steel charge holder, one free face blasting models which adapt the blast induced stress waves were simulated by dynamic fracture process analysis (DFPA) code. In addition, the general blasting models were also simulated to investigate the fragmentation effectiveness of the U-shaped steel charge holder in rock blasting.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.235-243
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• 2011

In this study, a control blast method, which utilizes crack guide holes, is suggested to achieve smooth fracture plane and minimize blast damage zone (BDZ) in smooth blasting. In order to verify the effectiveness of crack guide holes on the fracture plane control in blasting, fracture process analyses which consider regular smooth blasting and guide hole smooth blasting had been conducted and the fracture planes resulting from the analyses had been compared. The analyses models considered the ignition of the blast holes using detonation cords and each guide hole placed between blast holes. From the results, the smooth blasting utilizing guide holes showed lower fracture plane roughness than regular smooth blasting method in the hole spacing range between 20 to 40cm.

• Explosives and Blasting
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• v.34 no.3
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• pp.21-26
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• 2016

In case of urban blasting works at near neighbors, the size of one blasting should be minimized to reduce the vibration and noise. However, the complaints is not decreased due to increased numbers of blasting per day so that the period of blasting works become long. This case study is related to urban apartment construction site. In order to overcome the weakness of general detonators which is required many blasting times to meet the day productivity, we have been applied deck-charge blasting method using electronic detonators and then we successfully increased the day productivity with much less blasting times. Hence, we had effectively achieved the declined neighbors'complaints and shortening construction period.

• Explosives and Blasting
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• v.28 no.1
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• pp.40-54
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• 2010

The messer shield method applys mainly to a tunnel with small cross-section of a weathered soil or weathered rock district and is fulfilled mostly by man-power excavation. but in case that hard rock exposes on tunnel face, incredible is an application of the rock-splitting method using a hydraulic power or a blasting method. This study represents the case of a blasting method which can control to be practiced by the minimum charges of 125 g an initial vibration occurring at the cut instead of the rock-splitting method, even though water pipe and gas pipe are closely adjacent.

• Explosives and Blasting
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• v.28 no.2
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• pp.50-58
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• 2010

This study explores the slot-drilling method that has not yet enough been studied in Korea and intends to provide a theoretical framework for putting the method into practice in a construction site. The possible reduction of ground vibration by implementing slot-drilling methods is addressed. Two main subjects dealt with include the variation of vibration velocity that is based on the distance between the slot-drilling and the epicenter of blasting and the analysis of appropriate effective dimension of slot-drilling width and height to control blasting vibration. This study shows that effect of vibration reduction decreases when distance of the slot-drilling and the epicenter of blasting is getting larger and also reveals that there is a correlation between the slot size and the vibration velocity at any point.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.891-901
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• 2016

By comparing test blasting data experimented in three layered-structure polymorphic grounds to a geological profile, influence of blast vibration with respect to uncontrollable ground characteristics was analyzed. Inefficient blast have been performed without sufficient verifications or confirmations because insufficiencies with regard to experiments and data of blasting engineering on the layered structures to be irregularly repeated clinker layer consisted of volcanic clastic zones. It is difficult to quantify N values of clinkers within test blasting region because they have diverse ranges, or coverages. An absolute value of attenuation coefficient N in a field, estimated by blasting vibration predictive equation (SRSD), are lesser than criteria of a design instruction, meaning that vibrations caused by blast can spread far away, and the vibrational characteristics of blasting test No.1, indicating relatively small values, inferred by the geological profile, pressures of gas by the explosion may be lost into a widely distributed clinker layers by penetrating holes resulted from blast into vicinity of clinker layers located in bottom of soft rock layers at the moment of blast. As a result, amounts of spalling rocks are decreased by almost half. Also, ranges of primary frequencies in the fields are identified as similar to those of natural frequency of typical structures.