• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.117-129
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• 2009

Several researches have been done to estimate the earth pressure on a vertical circular shaft considering three dimensional arching effect and verified them by conducting model tests. However, any equation suggested so far is not applicable in case of multi-layered soils and/or C-${\phi}$ soils. In this study, new equation for estimating the earth pressure acting on the vertical shaft in c-${\phi}$ soils is proposed. A parametric study is performed to investigate the significance of the cohesion when estimating the coefficient of earth pressure in C-${\phi}$ soils and estimating earth pressures in vertical shafts. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by assuming a failure surface in layered soils and using the modified equation. This paper is Part I of companion papers focusing on the theoretical aspect of model developments; the experimental verification will be made in Part II.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.637-658
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• 2022

TBM tunnel is simple with the iterative process of excavating the ground, building a segment ring-build, and backfilling. Drill & Blast, a conventional tunnel construction method, is more complicated than the TBM tunnel and has some restrictions because it repeats the inspection, drilling, charging, blasting, ventilation, muck treatment, and installation of support materials. However, the preparation work for excavation requires time and cost based on a very detailed plan compared to Drill & Blasting, which reinforces the ground and forms a tunnel after the formation of tunnel portal. This is because the TBM equipment for excavating the target ground determines the success or failure of the construction. If the TBM, an expensive order-made equipment, is incorrectly configured at the assembly stage, it becomes difficult to excavate from the initial stage as well as the main excavation stage. When the assembled shield TBM equipment is dismantled again, and a situation of re-assembly occurs, it is difficult throughout the construction period due to economic loss as well as time. Therefore, in this study, the layout and plan of the site and the assembly process for each major part of the TBM equipment were reviewed for the assembly of slurry shield TBM to construct the largest diameter road tunnel in domestic passing through the Han River and minimized interference with other processes and the efficiency of cutter head assembly and transport were analyzed and improved to suit the site conditions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.489-501
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• 2017

The collapse accidents during a open ground excavation in urban areas not only lead to human injuries and material damages in the construction site, but also lead to road sinks and damages to the adjacent facilities due to settlement of ground around the construction site. Therefore, during a open ground excavation in the urban areas, it is necessary to thoroughly prepare for prevention of collapse accidents, and consider whole construction stage such as planning, design and construction. In this study, the priorities to be managed mainly were obtained in order to prevent collapse accidents during a open ground excavation. After analyzing results from past accidents cases for open ground excavations, priorities were evaluated regarding collapse-inducing elements using the Delphi technique which is a decision-making method by consensus among experts. As a result, insufficient groundwater treatment, bad geotechnical investigation and instability on construction, etc. were obtained as priorities for prevention of collapse accidents.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.328-335
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• 2012

The resource-based estimating based on standard unit price of construction work was estimated by multiplying the price per standard unit of work on the amount of labor, material, equipment use time. However, limitation of the resource-based estimating way does not adequately reflect the actual transactions prices. On the subject of water tunnel excavation as a new attempt to overcome these limitations, this study analyzed productivity by work type into cutter inspection/ exchange, TBM maintenance, TBM inspection/refueling, subsequent installations, tramcar, operating change, a cave-underground reinforcement / rock reinforcement, safety / meetings and analyzed actual cost estimating and the net advance rate based on this analysis result. Actual cost estimating calculation approach presented in this study can be utilized as a useful tool to predict the actual cost estimating in the TBM water tunnels field.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2002.03a
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• pp.19-26
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• 2002

서울시에 건설될 새로운 내부 남부순한 도로는 제2 성산대교와 서쪽의 주요 고속화 도로를 연결하는 초고속 도로망을 구축할 것이다. 노선연장은 지하구조물 10.4km를 포함하여 총 34.8km에 달한다. 도로망이 완성되면 수도 서울 중심가의 심한 교통체증은 상당부분 완화 될 것이다. 공사비 7000억원에 이르는 대규모의 서울 남부순환 도로는 3차선 병렬터널 3개 공구를 포함하는 것으로 계획되어졌다. 이들 터널은 3차선, 일방향, 병렬터널로서 계곡부를 관통하며 굴착공법은 대부분 발파공법으로 계획되어져 있다. 가장 긴 관악터널은 지질조건이 복잡하며 따라서, 이런 지반에 적용성이 좋은 발파공법에 의한 굴착으로 계획되어졌다. 특히, 갱구부는 지질상태가 매우 불량하여 풍화암 자연상태로 설계하는 것이 불가능하였다. 설계자들은 터널 화재와 교통사고 등과 같은 터널내에서의 긴급상황에 대한 최적의 대책 수립에 중점을 두어야만 했다. 관악 터널 상부에 위치한 수로관을 통과하는 방법을 찾는 것이 당면 최대 관건이었다. 또한, 갱구부 주변지역의 환경을 보존하고 현장의 자연적인 아름다움 을 유지하기 위하여 굴착량을 최소화하는 공법선정이 중요하였다.

• 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 Korean Tunnelling and Underground Space Association
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• v.5 no.2
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• pp.161-174
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• 2003

Applicability of the Decision Aids for Tunneling (DAT) technique is investigated in this study to better understand the efficiency of the decision making process during tunnel construction. For this, a traffic tunnel under construction is adopted and information on the construction procedure, i.e., overall geology, unit cost and construction time for each excavation process, is provided periodically. Various scattergrams in which cost-time simulation results are plotted are obtained according to the simulation methods and final prediction on the construction time/cost is made. It is found that the uncertainty in the cost distribution is greater than the uncertainty in the time distribution for each cycle simulation and the uncertainties in time and cost for the one time simulations are comparable. Future work will be concentrated on the updating scheme using the face mapping data and various parametric studies will also be performed.

• Explosives and Blasting
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• v.24 no.1
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• pp.39-48
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• 2006

The various alternatives to reduce the construction period and cost in the wide and long tunnel have been attempted recently. However, the concrete lining forming process after finishing tunnel excavation may delay construction period considering the specific conditions of the wide and long tunnel. The concrete lining is indispensible for the road tunnel. For this reason, the blasting-lining synchronizing study had been carried out to reduce construction period in the Gyea-Ryong Tunnel. Lining models were installed at four different distance conditions the floor of the tunnel. After model installation, hundreds of blasting vibration measurements and concrete material tests were performed to calculate the safe distance between blasting point and concrete lining form. The study also introduces a method which can obtain the better ability of construction by improving working environment with the ventilation and the relocation of tunnel equipments in the working places.

• Journal of Korean Society of Disaster and Security
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• v.11 no.1
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• pp.23-30
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• 2018

The purpose of this study is to provide an integrated solution which includes construction process that allows effective tunnel grouting and to develop a tunnel grouting programme by establishing an algorithm through theoretical analysis on tunnel grouting construction technique factors. In order to verify the developed tunnel grouting procedure and the effectiveness of the programme, they are applied on certain work sites. Values after the application are Lu = 0.31 and ground-water inflow = 0.191/min where as the pre-application value of ground-water inflow is 6.691/min which is approximately 35 times larger. This shows that Tunnel grouting construction effect is significant and suggests the possibility of the application of the process and the programme on future tunnel grouting construction.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.169-176
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• 1999

본 논문은 지하수 흐름하에서의 풍화 잔류토의 세립자 유동특성을 파악하기 위한 수치모델을 개발하고, 실내에서 실시한 수리 모형실험을 통하여 수치모델의 적합성을 규명하였다. 한국의 풍화 잔류토는 점토와 모래의 중간 상태의 특성을 보이는 관계로 기존의 토립자 유동모델중 점토 또는 모래에 적합한 모델에 의해서는 정확한 유동특성의 파악에 한계가 있었다. 따라서, 본 연구에서는 한국의 풍화 잔류토에 적합한 세립자 유동모델을 제시함으로써 풍화 잔류토를 대상으로 시공되는 굴토공사, 댐 축조공사, 그리고 터널공사시 지하수 유입에 따른 세립토사의 유실특성을 이론적으로 규명하였고, 현장에서 배수재로 광범위하게 쓰이고 있는 토목섬유인 부직포의 투수 및 배수특성을 검토하였다