• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.2
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• pp.151-160
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• 2004

This study has carried out a series of field investigation for a ASSM railway tunnel which was constructed several decades ago. It appears that the tunnel lining was cracked in the region of arching structure. Precise inspection is carried out for this region with various non-destructive testing equipments. Based on the inspection results, the cause and the effect of tunnel defects were discussed by conducting the evaluation of tunnel safety with numerical analysis.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.19-25
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• 2005

A tunnel that uses the RMR method or the Q-system is called a 'modem tunnel' because the New Austrian Tunneling Method (NATM) is not employed, even though shotcrete and rock bolts are used as support. It is known that the modem tunnel, which is supported by shotcrete, is basically different from the conventional tunnel, which is supported by steel ribs. In order to preserve the load-carrying capacity of the rock mass, loosening and excessive rock deformations must be minimized. Although it is known that this can be achieved by applying shotcrete in the case of the modem tunnel, this has not been clearly demonstrated. In order to inspect the distinctions between the conventional tunnel and the modern tunnel, their support characteristics and the rock loads of the rock mass classifications are compared. Terzaghi's rock load classification was used as the conventional tunnel's representative rock mass classification. The RMR method and the Q-system were adopted as the modem tunnel's representative rock mass classification. The study's results show that the load-carrying capacity of shotcrete, when used as the main support in the modern tunnel, is greater than the load-capacity of the steel ribs used in the conventional tunnel. Because it has been verified that the rock loads of their rock mass classifications are not different, then, according to the rock mass classifications, the load-carrying capacity of the rock mass of the modern tunnel, which uses shotcrete, is not greater than that of the conventional tunnel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.27-36
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• 2018

Although the current evaluation system has been revised four times since it was revised in 1996, it is insufficient to utilize it as a basis for predicting the performance degradation from the long-term viewpoint and prioritization decision for the budget input due to the evaluation system limited to securing the structural safety. Therefore, this study proposes a new evaluation system suitable for the performance evaluation of conventional (ASSM) tunnels among the various types of existing road tunnels using Delphi technique and AHP technique. Since the existing evaluation systems and evaluation items in domestic and overseas are limited in scope of evaluation criteria, the survey was conducted in conjunction with closed questionnaires on existing items and open questionnaires for eliciting new items. The validity of the questionnaire results were verified and the performance evaluation factors suitable for conventional (ASSM) tunnels were derived. After calculating weighted value of the derived evaluation item using AHP technique, a new evaluation system is proposed to meet the characteristics of the ASSM tunnel, so that they can be used as reference materials for revising and supplementing detailed guidelines of performance evaluation in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.150-159
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• 2011

The need of securing the stability and extending service lives by efficient maintenance of deteriorated tunnels for several decades has been increased. The stability and the usability of conventional tunnels can be decreased by change of physical properties of the surrounding ground, geometrical properties of the tunnel, an underground water level, environmental conditions, oxidation of lining and the breakdown of constituent materials. In respect of a long-term view, it is need to check all sorts of degradation, the degree of damage and durability to improve the serviceability and to come up with measures to maintain effectively. This paper is about study to analyze the stability of conventional tunnels(American Steel Support Method. ASSM). Three tunnels are chosen in those built in the 1930s and 1960s and the locations of tunnels are selected variously(ChungCheong, GyungBuk, GangWon, Jeolla, etc.) to secure reliability of this study. The state of repair and reinforcement of linings, cracks, and thickness and strength of lining of conventional tunnels in service are researched, compared and analyzed. The crack gauge, the GPR, the schmitt hammer was used for the crack investigation, cavitation, the strength respectively. By using these, the comparative analysis for conventional tunnels was conducted. As a result, there are more cracks in tunnels built in the 1930s than those of tunnels built in the 1960s, and lining strength of the 1930s is higher than those of the 1960s. The thickness of lining in tunnels built in the 1960s is higher than those in tunnels built in the 1930s. In proportion to thickness, cavitation occurred more frequently in tunnels built in the 1960s compared to those in tunnels built in the 1930s.

• Tunnel and Underground Space
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• v.17 no.5
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• pp.428-434
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• 2007

Displacement of tunnel face is important issues for the evaluation of tunnel safety. In this study, conventional convergence and displacement data measured from horizontal inclinometer were analyzed to investigate the trend and characteristics of tunnel deformation during construction. Trend of measured displacement agreed with general understanding of tunnel deformation prior to excavation. It shows that displacement measured from horizontal inclinometer can be used to preestimate the total deformation of tunnel.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03a
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• pp.410-430
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• 2004

근년에 와서 터널이 건설 프로젝트의 주요 분야로서 국가 건설인프라의 중심 축으로 떠오르는 분야임을 감안할 때 그 중요성은 건설분야뿐만 아니라 국가기본사업 및 사회 간접시설 등 전반에 걸쳐 있다. 국내 터널 기술은 재래식 굴착에서 근접시공, 도심지 연약지반 통과, 대단면 굴착 등으로 이어져 그 한계에 도전하고 있다. 또한, 세계적 추세인 기계화 시공에 대해서도 진일보하고 있다. 최근의 전파, 기계, 정보통신 기술의 발달은 터널 현장에서 기계화 시공의 비율이 높아지도록 견인하고 있으며 삶의 질 향상과 더불어 일반적인 터널의 기능에 첨가하여 쾌적한 터널을 요구하는 실정이다.(중략)

• Magazine of korean Tunnelling and Underground Space Association
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• v.20 no.4
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• pp.74-86
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• 2018

• Geotechnical Engineering
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• v.22 no.7
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• pp.17-27
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• 2006

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.81-89
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• 2012

The existing tunnel in urban area can be enlarged because of requirement of road-widening by traffic growth. The protector with rectangular cross section can be set up in the tunnel, which will be constructed for enlargement of width, to solve traffic jam around the tunnel. It is impossible to install the rockbolt in the lower area of tunnel due to a limited space between the protector and cutting surface. The objective of this study is to suggest the method of shotcrete thickness increase instead of rockbolt installation in the side wall of tunnel for the stability of tunnel. Numerical analysis was performed to evaluate displacement at the crown of tunnel, convergence of tunnel, and stress in shotcrete lining in 3-lane and 4-lane NATM tunnels enlarged from 2-lane conventional tunnel. There were three types of analysis condition, rockbolt installation, no rockbolt installation, and increase of shotcrete thickness without rockbolt in the side wall of tunnel. There was no difference on the displacement at the crown and the convergence of upper tunnel. In the lower tunnel, the convergence in case of no rockbolt installation was larger as maximum 1.3mm than that in case of rockbolt installation. The stress in shotcrete lining in case of no rockbolt installation was larger as maximum 1.3MPa than that in case of rockbolt installation. Numerical analysis was performed to compare the behavior of shotcrete with rockbolt with that of shotcrete, which its thickness was increased, without rockbolt. The shotcrete has an increase of 20%(250mm ${\rightarrow}$ 300mm, 4-lane tunnel)~25%(200mm ${\rightarrow}$ 250mm, 3-lane tunnel) in its thickness to reduce the stress in shotcrete lining. The behavior of shotcrete lining increased the shotcrete thickness by 20%~25% was similar to that of existing shotcrete lining with rockbolt.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.139-147
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• 2003

The most tunnel damage such as cracks or leakage which exist in tunnel lining commonly, is caused by the voids where exist behind the tunnel lining, through the tunnel safety inspections. These voids were analysed to affect to a stability of a running-tunnel seriously. The aim of this paper is to develope the lightweight foam concrete for tunnel backfilling material using stone-dust of cake state and to apply the lightweight foam concrete developed to the old tunnel. This paper shows the basic properties of lightweight foam concrete mixed with stone-dust including flow rate, unit volume weight, absorption rate and compressive strength. In addition, according to the designed compound ratio, the lightweight foam concrete was applied to the ASSM tunnel for an application assessment. The engineering application of the lightweight foam concrete as the old tunnel's backfilling material was confirmed in this assessment.