• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.480-488
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• 2010

The CGS method is non-discharge replacement method improving ground stiffness by the effect of static compaction with injecting very low slump mortar into ground, and is applied for increasing bearing capacity and filling ground cavity by lifting or restoring differential settled structures and preventing differential settlement. This paper suggests design of ground improvement and construction case history for civil engineering structures by CGS method. This method can be used for reinforcing soft ground and liquefaction of loose sandy soil. This method was used in SongDo area in Incheon Economic Free Zone due to its low vibration of ground while it can improve the soft soil where underground structures(subway and box culvert) are already existed.

• Tunnel and Underground Space
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• v.7 no.2
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• pp.116-129
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• 1997

The objective of this study is to predict the minimization effect of the noise and vibration during the construction and the train operation regarding to the design modification of the Taegu Subway Line No. 1. It was suggested optimal control blasting methods to reduce the causing vibration Nuance to the resident in City Taegu and also proposed the better governing method to decrease the environmental hazard to the near buildings and residents during the train operation. When the high-density gaseous reaction of explosion products exerts a high pressure in motion outward, a dynamic stress field will be created in the surrounding buildings. Therefore, in the region close to the charge, permanent damage begins to occur at a great critical level of partial velocity, that is difficult from different structure as working conditions. It is reliable to predict that the damages could be reduced if we know the peak velocity and the exact reasons through the conducting of detail studies of structural analysis of the related buildings with the optimal blasting designs. A blasting technique should be deemed to take advantage of the reduction of damage of the surrounding rocks and structures to improve the in-city blasting. This is a typical in-city blasting operation where success depends on closely controlling the ground vibrations in case of better designed blasting methods. There are techniques that can be applied to prevent large vibrations from damaging the important buildings through the Route Modification of the Taegu Subway Line No. 1.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.71-77
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• 1999

Exposed gas pipeline in underground, especially subway construction site, has been continuously vibrated by vehicle above ground. Because this vibration can cause unexpected damages to pipeline, we had measured and analyzed the vibration. This paper presents results of the vibration analysis of exposed gas pipeline and the results are as follows. The major vertical vibration frequency of pipeline was about 13 Hz and the other frequency components disappeared when the vibration transmitted to I-beam and wire rope. Existence of wooden casement had not affect vibration of exposed gas pipeline. The results of modal analysis by experimental and analytical methods have good agreement and it is also shown that exposed pipeline has possibility of resonance at second mode.

• Geotechnical Engineering
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• v.11 no.3
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• pp.55-68
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• 1995

This paper is the analysis of the relationship between RQD and decay constant, blasting vi bration constant of cube root scaling and square root scaling, through experimental blast ins test in subway construction for excavation of shaft hole by bottom blasting. The magnitude of particle velocity is largely effected by the distance from blasting source, the maximum charge per delay and the properties of ground. In order to verify the effects of ground properties on blast-induced vibration, the relation-ship between magnitude of blasting vibration and Rock Quality Disignation which stands for joint property was studied. The results of test are verified that blasting vibration constant "K" and the absolute value("n") of decay constant relatively increse as RQD increased. According to the result, it can be predict the particle velocity by the blast -induced vibration in bottom blasting pattern.om blasting pattern.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.2
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• pp.135-146
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• 2003

This paper presents the effect of ground vibration induced by vibrohammer and RCD on adjancent subway tunnel performance using FDM program. Firstly, the stability criteria for structures near vibration source were proposed according to existing data, then peak particle velocity around tunnel was estimated based on detailed information of vibrohammer and existing formula for dynamic loads through numerical analysis. The peak particle velocity induced by RCD bit rotation was also estimated using surveyed data and formula. Consequently, displacement and stress responses were obtained at crown, shoulder and spring line and compared with the criteria to check stability of tunnel.

• Explosives and Blasting
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• v.23 no.3
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• pp.57-74
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• 2005

In the past, explosives like dynamite was used to blast rock. However, today it is difficult to use explosives in urban blastinglike excavation for subway, building, and housing land. According to Korea Department of Construction and Transportation's proposal for blasting design manual and test blasting, from TYPE I blasting to TYPE IV blasting are recommended when we determine 0.3cm/sec(centisec) as a maximum allowable ground vibration with a distance between $25m\~120m$ from structures. This article was written to introduce one of TYPE I (reck blasting within 25m from structures) blasting method, Nano-Plasma blasting method. When Nano-Plasma blasting method is applied in urban blasting job, ground vibration (15m away from blasting point) is expected 0.1cm/sec, which is only half of a ground vibration when low ground vibration blasting method is applied. By this unique characteristic, Nano-Plasma blasting method is epochal urban blasting technique.

• Journal of the Korean Professional Engineers Association
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• v.23 no.6
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• pp.41-46
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• 1990

First of all, Under given condition such as bit gage of 36mm Drill bit with right class of jack-logs 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. (equation omitted) A=Activated Area A=ndi=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 ø 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 one of contineous works to above a determination of empirical equation on the cautious blasting vibration with Crawler Drill(ø 70-75mm) in long distance. V=41(equation omitted) V=124(equation omitted).

• 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. $V=41(D/\sqrt[3]{W})^{-1.41}$ $30m\le{D}\le{100m}$ $V=124(D/\sqrt[3]{W})^{-1.66}$ $100m\le{D}\le{285m}$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.85-95
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• 2009

In urban areas, blast excavation adjacent to tunnels is carried out frequently. It is generally required to secure static and dynamic stability of nearby tunnel structures for any such activities. Although there is some national guidelines for static safety, there is little guides to risk zoning controling the dynamic behavior of the underground structures. In this study, impacts on the blast-induced vibration are investigated using numerical study. An attempt to define the restricted area of blast adjacent to subway tunnels was also made. Particular concerns were given to tunnel depth and ground types. By carrying out the parametric study on depth and ground patterns, the envelope of blast distance of which dynamic response on the lining is controlled under 1 cm/sec, is established. It is shown that the increase in depth has increased the required safety distance slightly until the distance of 3.5 times of the tunnel diameter. Despite small changes in safety distance, it can be generally said that the effects of depth and stiffness of the ground is not significant in controlling the particle velocity of the tunnel linings.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.618-626
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• 2011

Recent development of related technologies and efficient utilization of the entire country for the purpose of railway construction, and plans are being accelerated. the railway noise has been improved by increasing the high speed railway station, and accelerating the existing trains. Nord2000 which is an overseas noise prediction equation could not be applied directly to the domestic railway vehicles. So the specific vehicles in the Nordic countries which is a similar specification to domestic trains should be selected. Nord2000's accuracy was compared to Schall03, CRN's. Prediction of Ground impedance and Roughness class were carried out at different. In this paper, the result of selected vehicles for Nord2000 was as follows. S-1aX2 was for express trains, N-$^*2c$-3b was for Mugunghwa, S-Pass/wood was for Saemaul, N-4a was for freight trains, N-3a was for subway, the calculation time for Nord2000 took longer than others, in addition, Ground absorption was indispensable to calculate a noise map for Nord2000. As a result, CRN's prediction noise levels at Wonju-si was closest to the measurements. However, the predicted noise levels of Nord2000 was the most accurate.