• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.197-204
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• 2006

A large sectional tunnelling method using Shield TBM is expected to be popular as domestic demand of long tunnel gets growing. Although a shield tunnelling method has been recognized as prominent method in consideration of stability and applicability in shallow and poor ground, the cases of accident and constructional trouble have been often happened due to unexpected poor ground condition, or selection and use of improper shield machine. Especially, troubling cases at tunnel face are frequently occurred, so supporting pressure control of tunnel face would be the main issue for securing safer and more efficient tunnel excavation using Shield TBM. In this point, we carried out the numerical feed-back analysis to compare the ground deformation pattern with theoretical result at tunnel face.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.435-450
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• 2020

The divergence section of a double-deck tunnel can be divided into a 'widening pre-divergence section', a large cross-section with a cap shape and a 'post-divergence section' where the separation between the main and the branch tunnel is made. Since the cross-section of the widening pre-divergence section is considerably larger than that of the post-divergence section, the influence of excavation due to the different sizes and shapes in the cross-section should be considered in the examination of the tunnel stability. In this study, the effect of the preceding excavation, that is the excavation of the widening pre-divergence section, on excavation stability of the post-divergence section was examined by varying the excavation methods and bench lengths through 3D finite element analysis. The results showed that although the effects of the excavation methods and the bench lengths are not significant on the variation of principal stresses, the preceding excavation causes a relatively large variation on the stresses which may have an impact on the stability of the post-divergence section from the comparison of Stress-Strength Ratio (SSR) between the cases with and without the consideration of the preceding excavation effect by 2D finite element analysis.

• Magazine of korean Tunnelling and Underground Space Association
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• v.13 no.4
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• pp.77-88
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• 2011

• Tunnel and Underground Space
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• v.34 no.4
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• pp.413-420
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• 2024

When planning gripper TBM, which is highly applicable to urban areas, the excavation characteristics are not considered. In addition the excavation stability and constructability are degraded by installing reinforcements in the adjacent construction site considering the relaxation load theory of the pre-existing NATM. In this study, a rationalization plan for the support was proposed considering the excavation characteristics of gripper TBM when planning reinforcements for adjacent pre-existing construction. The effect of excavation on the surrounding ground was analyzed by conducting three-dimensional stability analyses considering the construction stage for each excavation phase. In NATM, relaxation phenomenon is concentrated in tunnel face due to non-supporting time occurring simultaneously with excavation, but gripper TBM supports the ground around the tunnel face through the cutter head and skin plate, simultaneously causing ground relaxation behind the skin plate. Considering these excavation characteristics, problems in reinforcement planning for adjacent construction at the study site were pointed out. A performance improvement plan for a reasonable supporting system was proposed.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.148-156
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• 2019

In urban area, the use of mechanical excavators (e.g., TBM and roadheader) has been increasing in construction of tunnelling and underground space. The undercutting technology, which is modified from the conventional rock-cutting concept, has been developed by advanced countries. Therefore, research on the latest technology of mechanical excavation is required, and keeping carrying out research on conventional mechanical tunneling methods at the same time. In this study, as a fundamental study of the undercutting technique, the principle and concept of the undercutting were introduced, as well as the current status of the research of advanced countries. The undercutting is applicable as a full-face excavation method for the tunnels and underground spaces, as well as an auxiliary(partial-face excavation) method for extension of the existing tunnels.

• Explosives and Blasting
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• v.35 no.2
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• pp.1-8
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• 2017

In this study, the characteristics of a new rock cracking method using steam pressure are briefly presented. The rock cracking method was originally developed as a means to decrease the ground vibrations from underground rock excavations. The validation tests were also conducted by applying the method to an actual rock tunnel under construction. The ground vibrations were measured in the vicinity of the test site. The measured vibration results were compared with the values predicted by an attenuation equation, which had been proposed by a company in Japan. Also, a simple cost assessment for the method was conducted to demonstrate its cost effectiveness in underground tunnel excavations.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.215-220
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• 1998

터널공사에서는 지산의 강도에 따라 선정된 굴착공법을 이용하여 굴착 된 단면에는 굴삭된 터널의 안전과 시공상 능률을 증진시키고, 장기간에 걸친 터널의 사용에 대한 충분한 신뢰성을 갖추기 위하여 지지공$\cdot$라이닝콘크리트 등이 설치된다. (중략)

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.397-419
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• 2012

The pressurizing support tunneling method has been developed that overcomes shortcomings of conventional trenchless methods and applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies higher pressure than the pressure relaxed by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through 3D numerical analyses. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long ramp tunnel that passes under ${\bigcirc}{\bigcirc}$ Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months which decreases construction time to 35% compared to conventional methods, and ground displacement was almost negligible.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.171-172
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• 2010

본 논문에서는 하나로폐기물을 처분 원가대상으로 설정하고 처분 단위모듈당 주요 원가를 추정하였다. 추정결과, 처분용기 직접재료비가 제일 많이 소요되며, 그 다음은 처분공 굴착비인 것으로 나타났다. 이러한 이유는 처분공 굴착은 발파공법이 아닌 그라인더로 굴착하는 정밀공법이기 때문에 굴착단가가 1,143,963원/$m^3$으로 매우 비싸기 때문이다. 따라서 주요 원가동인의 비용 점유율은 처분용기 재료비가 44.7%, 처분공 굴착비가 27%로 나타났다. 그리고 처분터널 굴착비는 비교적 비용 점유율이 적은 2.3%로 계산되었다. 이러한 이유는 처분터널은 처분공과 달리 발파기법으로 굴착하기 때문에 굴착단가가 처분공 굴착단가에 비해 저렴하기 때문이다.

• Magazine of korean Tunnelling and Underground Space Association
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• v.7 no.3
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• pp.24-35
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• 2005