• Geomechanics and Engineering
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• 제35권2호
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• pp.149-163
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• 2023

This paper presents stability evaluation of unlined tunnels with semi-circular arch and straight sides (SASS) driven in non-homogeneous and anisotropic undrained clay. Numerical analysis has been conducted based on lower bound finite element limit analysis with second order cone programming under plane strain condition. The solutions will be used for the assessment of stability of unlined semi-circular arch tunnels and tunnels in which semi-circular roof is supported over rectangular/square sections. The stability charts have been generated in terms of a non-dimensional factor considering linear variation in undrained anisotropic strength for normally consolidated and lightly over consolidated clay with depth, and constant undrained anisotropic strength for heavily over-consolidated clay across the depth. The effect of normalized surcharge pressure on ground surface, non-homogeneity and anisotropy of clay, tunnel cover to width ratio and height to width ratio of tunnel on the stability factor and associated zone of shear failure at yielding have been examined and discussed. The geometry of tunnel in terms of shape and size, and non-homogeneity and anisotropy in undrained strength of clay has been observed to influence significantly the stability of unlined SASS tunnels.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.121-134
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• 2002

Tunneling is a very dangerous and expansive work. Especially, the concrete lining works need many long hours and much cost. As an alternative, the unlined tunneling methods including NMT have been developed in various country. These methods have advantages in cost, time and quality. In Korea, many considerations have been conducted to apply the unlined tunneling method in comparatively good rock. Since primary reinforcements play the role of the final supporting system in unlined tunnels, the initial stiffness and long term durability of reinforcements are very important for tunnel safety. To establish the reinforcements standard suitable to Korea, we investigated the foreign standards and construction cases, comparing geological and construction conditions of foreign land and Korea. As the result, we have proposed the standard of primary supporting system for unlined tunnel in aspects of material, design, construction and quality control etc.

• 터널과지하공간
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• 제10권4호
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• pp.544-552
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• 2000

노르웨이의 지질은 굳은 기반암, 높은 산악, 깊은 계곡과 피요르드로 특징 지울 수 있으며 이러한 지질학적 특성을 배경으로 많은 터널과 암반공동이 개발되었다. 터널 굴착에 종사하는 근로자들의 인건비가 매우 높음에도 불구하고 노르웨이는 이러한 터널과 암반공동의 건설에서 세계에서 가장 높은 경쟁력을 유지하고 있다. 기반암이 견고하다는 지질적인 장점 외에도 노르웨이가 저렴한 가격으로 굴착을 할 수 있는 요인은 무지보압력수로 터널, 압기완충공동, 수중관통발파와 같은 암반굴착기술의 혁신과 합리적인 계약체계, 축적된 경험으로부터 발전된 효율적인 작업 팀의 구성 및 작업방식 등이다. 본 논문에서는 지하공간 활용을 증대시킬 목적으로 노르웨이의 굴착기술을 분석하였다.

• Advances in Computational Design
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• 제5권4호
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• pp.417-443
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• 2020

Tunnels have been an integral part of human civilization. Due to complexity in its design and structure, the stability of underground structures under extreme loading conditions has utmost importance. Increased terrorism and geo-political conflicts have forced the engineers and researchers to study the response of underground structures, especially tunnels under blast loading. The present study has been carried out to seek the response of tunnel structures under blast load using the finite element technique. The tunnel has been considered in quartzite rock of northern India. The Mohr-Coulomb constitutive model has been adopted for the elastoplastic behaviour of rock. The rock model surrounding the tunnel has dimensions of 30 m x 30 m x 35 m. Both unlined and lined (concrete) tunnel has been studied. Concrete Damage Plasticity model has been considered for the concrete lining. Four different parameters (i.e., tunnel diameter, liners thickness, overburden depth and mass of explosive) have been varied to observe the behaviour under different condition. To carry out blast analysis, Coupled-Eulerian-Lagrangian (CEL) modelling has been adopted for modelling of TNT (Trinitrotoluene) and enclosed air. JWL (Jones-Wilkins-Lee) model has been considered for TNT explosive modelling. The paper concludes that deformations in lined tunnels follow a logarithmic pattern while in unlined tunnels an exponential pattern has been observed. The stability of the tunnel has increased with an increase in overburden depth in both lined and unlined tunnels. Furthermore, the tunnel lining thickness also has a significant effect on the stability of the tunnel, but in smaller diameter tunnel, the increase in tunnel lining thickness has not much significance. The deformations in the rock tunnel have been decreased with an increase in the diameter of the tunnel.

• 자연, 터널 그리고 지하공간
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• 제3권1호
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• pp.55-59
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• 2001

• 한국터널지하공간학회 논문집
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• 제5권2호
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• pp.209-216
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• 2003

현재 국내에서는 굴착 후 록볼트, 숏크리트와 콘크리트 라이닝을 현장에서 타설하는 NATM이 일반적인 터널공법으로 정착되어있는 상태이다. 이에 반해 최근 암반이 양호한 스칸디나비아 반도 부근의 국가를 중심으로 무라이닝 터널공법이 개발되어, 세계각국으로 확대되고 있으며 비교적 암반이 양호한 국내에서도 이러한 무라이닝 터널공법에 대한 적용성이 활발히 연구중 이다. 무라이닝 터널공법은 영구 무지보 지하공동에 대한 연구를 근간으로 발달되어 왔으며, 영구 무지보 지하 굴착에 관해서는 Barton이 수많은 사례기록들을 토대로 일반적인 조건 7가지를 제시하고 있다. 이 조건들은 Q-system에 관한 조건이지만, 국내에는 적용된 실적이 없는 조건이다. 따라서, 이 조건들에 의해 산출된 Q값에 대한 입력변수를 임의의 일반 도로터널단면에 적용하여, 불연속체 해석기법인 UDEC-BB을 사용하여 각 조건에 대해 수치해석적 검증을 실시하였다.

• Geomechanics and Engineering
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• 제25권2호
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• pp.99-109
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• 2021

Tunnel provide faster, safer and convenient way of transportation for different objects. The region where it is construction and surrounding medium has significant influence on the overall stability and performance of tunnel. The present simulation has been carried out in order to understand the behaviour of rock tunnel under static loading condition. The present numerical model has been validated with the laboratory scaled model and field data of underground tunnels. Both lined and unlined tunnels have been considered in this paper. Finite element technique has been considered for the simulation of static loading effect on tunnel through Abaqus/Standard. The Mohr-Coulomb material model has been considered to simulate elastoplastic nonlinear behaviour of different rock types, i.e., Basalt, Granite and Quartzite. The four different stages of rock weathering are classified as fresh, slightly, moderately, and highly weathered in case of each rock type. Moreover, extremely weathered stage has been considered in case of Quartzite rock. It has been concluded that weathering of rock and overburden depth has great influence on the tunnel stability. However, by considering a particular weathering stage of rock for each rock type shows varying patterns of deformations in tunnel.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.287-294
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• 2002

CAES which is called as a compressed air energy storage was firstly developed at Huntorf, German in 1978. The capacity of that system was 290MW, and it can be treated as a first commercial power plant. CAES has a lot of merits, such as saving the unit price of power generation, averaging the peak demand, improvement of maintenance, enlarging the benefit of dynamic use. According to the literature survey, the unlined rock cavern should be proposed to be a reasonable storing style as a method of compressed air storage in Korea. We decided the hill of the Korea Institute of Geoscience and Mineral Resources as CAES site. If we construct the underground spaces in this site, the demand for electricity nearby Taejon should be considered. So we could determine the capacity of the power plant as a 350MW, This capacity needs a underground space of 200,000㎥, and we can conclude 4 parallel tunnels 550m deep from the surface through the numerical studies, Design parameters were achieved from 300m depth boring job and image processing job.