• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.2
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• pp.135-148
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• 2013

Recently, road tunnels have become longer and the plans for long and deep road tunnel have been underway in urban areas. These long and deep tunnel excavations include NATM and TBM. Shield TBM is applied to around 80% of traffic tunnels in Europe, and approximately 30% of them in other developed countries. However, as much of equipment is imported from foreign countries at high prices and distribution rate of TBM tunnel is considerably low in Korea, NATM excavation method is commonly used. To increase TBM tunnel, it is necessary to do assure economic feasibility with the supply-demand of TBM equipment. For this, the selection of standardized TBM diameter is urgently needed. Therefore, the study aims to estimate the standardized optimum section properties of TBM by examining TBM excavation cross section utilization depending on the volume of traffic, the number of lane and its cross-section type(single or double deck), and ventilation system.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.570-580
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• 2005

NATM 터널에 작용하는 토압(이완하중)의 크기는 지형조건, 지질조건등에 따라 다르므로 정량적으로 산정하기에는 다소 어려움이 있으며, 실무적으로 Terzaghi(1946)가 제안한 암반의 이완하중을 적용하고 있다. Terzaghi 암반이완하중은 지형상 저토피, 편경사등을 고려하기에는 다소 무리가 있고 특히, 설계시 시공중 공용후 터널에 편토압이 작용한다고 예측하는 것은 더욱 어렵다고 할 수 있다. 본 연구에서는 저토피 편경사지형에서 터널의 문제점 보강대책방안에 대하여 종합 검토하였으며, 실제 지형상 저토피, 편경사를 이루나 암질이 양호하다고 판단되어 아칭 효과를 기대할 수 있을 것으로 예상되는 터널이 굴착과정중 설계시 추정된 지반조건과 상이하여 터널지보재(숏크리트)의 균열 및 이상 변위가 발생된 터널에서 보강대책방안으로 인버트폐합을 실시하여 안정된 터널굴착을 할 수 있었던 사례를 소개하고 저토피 편경사 지형에서 NATM 터널의 설계 시공시 유의사항에 대하여 검토하였다.

• Journal of the Korean Geotechnical Society
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• v.23 no.8
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• pp.87-95
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• 2007

This study analyzed ground settlement and ground stress depending on tunnel excavation and the ground reinforcing grouting methods for double line road tunnel through deep weathered zone. Diameter of double line road tunnel was approximately 12m and umbrella arch method and side wall reinforcing grouting were applied. The ring-cut split excavation method and CD-cut excavation method for excavation method were applied. Analyses of failure rate and vertical stress ratio show that the tunnel for which the height of the cover (H) was higher than four times the diameter, can be considered a deep tunnel. Comparisons of various excavation and ground reinforcement methods showed that CD-cut method results in lower surface and crown settlement, and lower failure rate than that obtained by Ring-cut split method. In addition, the side wall reinforcing grouting resulted in reduction of tunnel displacement and settlement.

• Tunnel and Underground Space
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• v.5 no.3
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• pp.193-204
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• 1995

Since the significance of measurements during tunnel construction is not recognized, measurements have not been implemented except for a few very important construction site. As the tunnel construction by NATM increases, the importance of measurements is being emphasized. But, due to the lack of practical experiences and theoretical background in measurements techniques, systematic measurements control system has not yet been established. In this study a measurements control system, successfully used in the urban tunnel construction, is introduced.

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.51-59
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• 2000

네일(또는 락볼트)은 토사터널의 NATM 시공 시 보강재로 사용되어진다. 그러나, 네일의 적절한 설치방법이 아직까지 정립되지 않았다. 본 연구에서는 네일의 길이와 위치를 변화하여, 그 효용성을 연구하였다. 그 결과, 네일이 지반보강을 위하여 토사지반에 사용될 시 경제적인 길이는 터널직경의 0.5배이다. 보강의 효용성은 네일의 위치에 따라 터널라이닝 측벽의 하부, 중부, 상부의 순서이다.

• Tunnel and Underground Space
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• v.4 no.1
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• pp.47-54
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• 1994

NATM has been applied most of tunnel design and construction in Korea these days. But, if you observe the tunnel designing method and construction conditions, you can see that the NATM isn's usually the most suitable to Korean geology. Also most of engineers feel that it is necessary to understand the NATM correctly adn to introduce another tunnelling principle which can be applied more economically and safely. So, we'd like to introduce a new tunnelling concept. Norwegian Method of Tunnelling(NMT) by comparing the NATM. The main character of NMT is that the forward prediction of conditions and the support of tunnel is done through geological investigation in details. And it can be compared with NATM, in which the support pattern is decided by monitoring of tunnel deformation on the construction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.637-652
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• 2012

The protector with the shape of '${\sqcap}$' in cross section can be set up in the tunnel, which can be constructed for enlargement of cross section, to keep traffic flow in the tunnel. It is impossible to install the rockbolt in the side wall of tunnel due to a limited space between the protector and cutting surface of side wall. The objective of this study is to suggest the optimum thickness of shotcrete lining without rockbolt on the side wall and to evaluate the stability of tunnel enlarged. Numerical analysis was performed to evaluate the displacement at the center of tunnel, the convergence of tunnel, and the stress in shotcrete lining in 4-lane NATM road tunnel enlarged from 3-lane NATM road tunnel. The vertical displacement at the center of tunnel and the convergence of crown in the tunnel with rockbolt in the side wall were almost similar to those in the tunnel without rockbolt in the side wall. The convergence of bench/invert and the stress in shotcrete lining without rockbolt on the side wall were greater maximum 0.57 mm and 1,300 kN/$m^2$ than those with rockbolt in the side wall. The increased convergence and the stress in shotcrete lining can be reduced in incerasing of thickness of shotcrete lining about 20% (5 cm) of standard thickness, 25 cm, of shotcrete lining.

• Explosives and Blasting
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• v.13 no.3
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• pp.42-53
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• 1995

• Explosives and Blasting
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• v.15 no.4
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• pp.35-43
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• 1997

• Proceedings of the Korean Geotechical Society Conference
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• 1984.06a
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• pp.1-23
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• 1984