• Tunnel and Underground Space
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• v.20 no.4
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• pp.260-266
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• 2010

In this study, wish to analyze effect that affect on each tunnel (right and left tunnel) according as proceeding of leading tunnel (right tunnel), following tunnel (left tunnel) and pilot tunnel excavation through behavior of tunnel and surrounding base by model tests. And stress-transfer mechanism that occurs from in-situ loosing area and arching effect by difference of stiffness ratio and overburden heights were verified experimentally. The model tests were carried out by varying the stiffness of reinforced area and overburden height, measured deformation of tunnel and displacement of surrounding base. The model tests followed exactly the real 2-Arch tunnel construction stages.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.3
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• pp.197-213
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• 2012

Disc cutter is a key cutting tool for rock excavation by TBMs. This study aimed to characterize the deformation of a cutter ring by strain measurement as well as infrared thermal camera measurement during a series of linear cutting tests for a hard rock. The strain measurement results indicated that the cutter ring clearly showed a linear elastic behavior. The data obtained from the infrared thermal camera measurement demonstrated that the maximum temperature increase in the cutter ring was below $14.4^{\circ}C$. The deformation and temperature increase of the cutter ring during rock cutting were insignificant in a given cutting test condition of this study.

• Tunnel and Underground Space
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• v.25 no.4
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• pp.383-396
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• 2015

It is analyzed the risk of building damage due to ground surface subsidence occurred during constructing a tunnel below buildings in sand-gravel layer. The overburden and the thickness of sand-gravel layer is about 20m and the width and the height of the tunnel are 12m and 8.6m, respectively. The tunnel is pre-reinforced by umbrella method with three rows of long steel pipes and grouting. Surface subsidence is measured at 36 points surrounding buildings and measured data are used to calculate optimized three dimensional subsidence surface. Depending on the building location, deflection ratio and horizontal strain are calculated to evaluate the risk of building damage. No damage occurs at the buildings because of both the small deflection ratios involved 1~4mm subsidence and compressive horizontal strains.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.4
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• pp.415-429
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• 2013

Performance-based design is becoming a key word for structure design in architectural and civil engineering spheres. In this paper, the need of the performance-based design, especially for tunnels, was enhanced by case study on the largely deformed cut-and-cover arch tunnel built by the prescribed design. In addition, this paper introduces effective method of subdivision on tunnel performance to help field engineer's comprehension. Case study dealing with the issue of typical backwards problem in geotechnical engineering was examined. First of all, the outline of the damaged culvert as well as the surrounding embankment is in detail described. The background, together with the cause of damage, is discussed based on the results of site investigation. Secondly, it was attempted to elucidate the deformation mechanism of the embankment by means of numerical analysis, and the countermeasures are proposed. Finally, the stability of the embankment with the countermeasures was evaluated.

• Tunnel and Underground Space
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• v.18 no.2
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• pp.107-117
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• 2008

In this study, the failure and deformation characteristics of steel fiber reinforced shotcrete (SFRS) which is a primary tunnel support was investigated to find out ground-support mutual behavior. To this end, a mock-up of a tunnel was made and experimented with the conditions of lateral earth pressure coefficient 0.5 and 1.0. During the tests, 11 hydraulic cylinders were used for loading. for better simulation of the lateral earth pressure effect, these cylinders were controlled separately by two groups; crown and side wall. Meanwhile, the deformation of shotcrete was measured by 11 LVDTs. Backfill material was also used fur better load transfer from hydraulic cylinders to shotcrete. For the validation of the mock-up test results, 3D numerical analysis is carried out. To do numerical analysis under the same condition as a mock-up test, the load history curve which was obtained during the test was tried to be simulated using an individual FISH routine in the numerical analysis.

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.53-60
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• 2023

Recently, along with the improvement of high-speed rail and road design speed, the proportion of tunnel construction work is increasing proportionally. In particular, the construction of long tunnels is rapidly increasing due to the mountainous terrain of our country. In this way, due to the trend of tunnels becoming longer, it is difficult to design and construct tunnels by avoiding fault zones. In the case of tunnel construction in mountainous areas, ground investigation is often difficult even during design due to the topographical conditions, making precise ground investigation difficult, and as a result, the upper part of the tunnel is damaged during tunnel construction. When fault zones, which are vulnerable to weathering, exist, the stability of the tunnel during excavation is directly affected by the fault zone distribution, strength characteristics, and groundwater distribution range. In particular, when a fault zone is distributed in the upper part of a tunnel, damage such as tunnel collapse and excessive displacement may occur, and in order to prevent this in advance, countermeasures must be established through analysis of similar cases. Therefore, in this study, when a large-scale fault zone exists in the upper part of a tunnel, the relationship and characteristics of damage to the tunnel structure were analyzed.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2007.10a
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• pp.365-374
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• 2007

본 논문은 터널의 지반-지보재 상호 거동을 규명하기 위한 연구로서 주지보재인 숫크리트의 균열, 파괴하중 및 변형거동을 실물크기의 갱도모형실험을 통해 확인하고 3차원 수치 해석을 실시하여 각각의 결과를 비교 검증하였다. 갱도모형 실험은 실제 터널과 유사한 크기의 터널을 제작하여 11개 실린더에서 측압조건에 따라 하중을 가하여 실험을 수행하였다. 3차원 수치해석 모델링은 갱도모형실험과 가능하면 같은 조건으로 해석하기 위하여 모형실험으로부터 로드셀 및 LVDT를 통해 얻은 하중-변위곡선이 수치해석 시에도 재현되도록 하여 수행되었다.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.330-332
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• 2017

본 논문에서는 숏크리트 지보재의 시간 의존적 경화특성을 고려한 터널 지보재의 3차원 유한요소해석을 수행하였다. NATM터널에 대한 기존 숏크리트 지보재 해석방식에 의한 결과화 제안된 시간 의존적 해석방법의 결과를 비교함으로서, 시간의존적 특성이 숏크리트 지보재의 응력 및 내공변위에 미치는 영향을 분석하였다. 시간 의존적 특성을 고려한 3차원 해석방법이 숏크리트 지보재의 변형을 과소평가 할 수 있음을 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.71-86
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• 2001

본 고에서는 도심지 터널의 과학적인 설계/시공을 위한 요소기술 확보의 일환으로 기존의 연구자들이 제시한 손상평가 기법을 토대로 터널굴착에 따른 지중매설관 손상여부의 예비평가를 위한 평가기법을 제시하였다. 제시된 기법을 토대로 다양한 경우에 대한 매개변수 연구를 수행한 결과 지반침하곡선의 경사 및 곡률 등 침하곡선의 제반특성에 기반을 둔 본 연구에서 개발된 손상평가기법의 평가결과는 변곡점의 위치에 많은 영향을 받는 것으로 나타났으며, 따라서 현장 특유의 지반특성 및 시공조건이 반영된 변곡점 산정식의 개발을 위한 지속적인 연구가 필요한 것으로 판단된다. 아울러서 터널심도가 터널직경의 2.5배 이하인 경우 손상도가 현저히 증가하며, 전반적으로 관의 재질이나 조인트의 형식에 관계없이 관체의 인장변형률이 손상여부를 결정짓는 인자인 것으로 나타났다. 본 연구에서 얻어진 결과를 종합하여 터널과 매설관의 상대적 위치 및 지반손실량에 따라 매설관의 손상정도를 정량적으로 평가할 수 있는 설계도표를 제시하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.133-151
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• 1991

In this paper an analytic discussion was made for a finite element analysis performed for the case study of Seoul subway NATM tunnel. The effects mainly discussed on the ground deformation analysis were the staged tunnel excavation and the excavated distance from a tunnel facing. The concept of ground characteristic line has been applied to properly consider the loading condition given by staged tunnel excavation so that the imaginary supporting pressure is applied on the excavated tunnel face. Discussions on the results of the performed finite element analysis were mainly made with respect to the ground settlement, tunnel displacement, earth pressure, stress mobilized in supporting members. And the three dimensional supporting effect due to the tunnel facing was evaluated based on an elastic closed-form solution and a result of two dimensional axisymmetric finite element analysis.