• Tunnel and Underground Space
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• v.15 no.2 s.55
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• pp.102-110
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• 2005

○ ○ tunnel that is located at Iksan - Jangsu freeway ○ ○, has collapsed during construction at the valley with shallow depth. Although, the site investigations, such as TSP, drilling exploration and so of indicated the presence of discontinuities in this section. The RMR was upgraded and the construction were carried out because that not only actual rock qualities were relatively good during construction but also the tunnel foe was stabilized. However, the tunnel was collapsed at the same time blasting of full face, and surface and underground water was infiltrated due to the settlement of the upper part of the tunnel face. To restore the collapsed section, 3-d tunnel stability analysis was performed and suitable reinforcement methods were chosen. The cavity of the upper tunnel face was stabilized by means of UAM and ALC injection. And the settlement was restored using L.W grouting method.

• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.55-61
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• 2009

Recently, highway tunnel construction has rapidly been increased due to the limited ground usage and geographical characteristic in Korea, i.e. Korea consists of 70% mountains. In this paper, it was analyzed tunnel collapse patterns in the weathered rockmass. Recent tunnel collapse pattern is quite different from that of past ten years. Tunnels in past years have been collapsed at shallow valley area because of shear strength decrease after heavy rain. Tunnels, which have been constructed recently, were collapsed at even the deeper ground position after primary support. Also in the case that proper reinforcement was not applied, it caused excessive crack at shotcrete and local collapse near tunnel face. In this paper, it was analysed the cause of the recent tunnel collapses and proper reinforcement for the collapsed tunnels.

• Geophysics and Geophysical Exploration
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• v.18 no.1
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• pp.14-20
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• 2015

Three-dimensional (3D) resistivity method is an effective tool in the engineering site survey because it can provide a 3D resistivity distribution of the site. In this study, we tried to find out faults, fractures and coal seams that can cause the collapse of the tunnel. We carried out 2D resistivity survey along 5 parallel lines and 11 cross lines and merged all the apparent resistivity data for 3D inversion. Finally, from the 3D resistivity image and drilling data we presented the 3D distribution of faults, fractures and coal seams that are considered the main cause of the tunnel collapse.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.241-248
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• 2003

In August 2002, side wall of OO tunnel, at the Bonghwa, Kungbuk province, Korea, was collapsed by abruptly applied heavy soil and water pressure to side wall from a inclined shaft when there was a heavy rain. These days, Inclined shaft is used for the purpose of reducing construction time, using ventilation system, using the out of carrying equipment and mucking when we construct tunnel in the world. Recently constructed tunnel has the source of inclined shafts, but the more time elapse, we lose the source of the inclined shaft such as exact position, condition, and the fact that whether inclined shaft is exist or not. Therefore, this study inspected the interior's appearance, analyzed structure to evaluate the reason of collapsing side wall and this study also performed the repairing work. Finally, we show improving maintenance method to prevent that similar accident that might be happened.

• Journal of the Korean Society for Railway
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• v.5 no.2
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• pp.84-92
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• 2002

For an efficient management and analysis of geological/geotechnical data obtained during site investigations or tunnel construction, Tunnel Information System(TIS) was developed in this study. TIS is running in CIS(Geographical Information System) which has a spatial data. TIS consists of two parts, the Tunnel Face Mapping System(FaceMap), to record a geological features by observations and measurements at the surface of the excavation, the Borehole Data Management System(BDMS), to store the different types of rock data related to boreholes. Using the database of collapsed tunnels, 20 in Korea and 84 in Europe and with an artificial neural network, an expert system was developed for inferring the tunnel collapse pattern and its volume. And by applying Geo-predict, the system developed, in tunnels under construction, observed data from the $\bigcirc$$\bigcirc$tunnl site was compared and analyzed.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.139-146
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• 1999

Geological and geotechnical surveys, in general, should precede the excavation to ensure the stability of the tunnel md should be followed up according to the various geological condition during the excavation. However actually the standard support patterns which were decided during the design phases used be insisted for the whole excavation phases in spite of the various geological conditions. When $\bigcirc$$\bigcirc$ tunnel was excavated up to 25m long, the severe displacement was generated in the Portal area of $\bigcirc$$\bigcirc$ tunnel and the tunnel face was pally collapsed. Therefore, this paper present the case study on construction associated with the Umbrella Arch Method used in silty ground by the NATM.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.323-330
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• 1999

Daylight collapse have been occurred by about 5.0m deep at ground surface and collapse of the crown head part of the tunnel have connected to the ground surface during first step of shotcrete work after blasting of upper half section of the tunnel driving at two-way double track tunnel face section on highway construction. This study is for a successful illustration case for the earth improvement method through applying such strengthening methods as cement milk grouting, S.G.R grouting,, steel pipe reinforced multi-step grouting etc. for the purpose of earth strengthening of loosened earth block occurred by tunnel collapse.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.848-857
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• 2008

In September 2007, the collapses of slopes and landslides are happened at Jeonlanamdo due to heavy rains accompanied with Typoon "Nari". The study area is the tunnel portal slope in new road construction site. This slope consists of pyroclastic rocks and has lots of faults. Particularly, the residual soils of the slope is deteriorated with yellowish mudstone layer as a results of chemical and physical weathering. This has a variety of swelling clay minerals and might be moved easily down at the gentle terrain. The inner factor of $\bigcirc\bigcirc$tunnel portal slope's collapse is the geological weak zone, the convergent topography, the inferiority of drainage and the heavy rain act on the failure as direct trigger.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.15-19
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• 2009

Due to the Japan's Kobe earthquake in 1995, a cut-and-cover tunnel, which is one of subway facilities, collapsed unexpectedly. As a result, also in Korea, seismic performance needs to be secured for the cut-and-cover tunnel and currently, the subway seismic design standard is based on the seismic performance. However, there is no standard for the damage level or stability level of a member for securing the seismic performance, and the definition of multi-level seismic performance is not sufficient. By contrast to this situation, in the Japan's evaluation method of seismic performance, design earthquake ground motion having reflected there into the subway driving stability is clearly defined and the seismic performance required for structures is classified in detail. This study analyzes the Japan's systematic evaluation method of seismic performance for cut-and-cover tunnels of subway.

• Tunnel and Underground Space
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• v.7 no.3
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• pp.191-201
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• 1997

Geological and geotechnical surveys, in general, should precede the excavation to ensure the safety of the tunnel and should be followed up according to the various geological condition during the excavation. However actually the standard support patterns which were decided during the design step used be insisted for the whole excavation steps in spite of the various geological conditions. OO tunnel was excavated with NATM and a support pattern type-V in weak rocks. When the tunnel was excavated up to 25m long, the severe displacement was generated in the portal area and the shotcrete was damaged to make the cracks and the tunnel face was totally collapsed. It might happen owing to the one-day heavy rain, but the exact reason for that accident should be found out and the new optimal support patternt needed. Consequently three dimensional numerical analysis was applied for the evaluation of the cause of the tunnel collapse instead of two dimensional analysis, because three dimensional analysis can show better the real field phenomenon than two dimensional analysis in which the load distribution methods are adopted for the tunnel excavation. We could simulate the actual situations with three dimensional finite difference code and propose the new optimal support patterns.