• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.133-144
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• 2004

Pre-reinforcement ahead of a tunnel face using long steel or FRP (Fiberglass Reinforced Plastic) pipes in NATM(New Austrian Tunnelling Method), known as the RPUM(Reinforced Protective Umbrella Method) or UAM (Umbrella Arch Method), is the promising method to sustain the stability of a shallow tunnel face and reduce the ground settlements. In addition, horizontal reinforcing of the face is recently emphasized to improve the stability of the face. However, the characteristics on longitudinal arching around the face have not yet been established quantitatively with the RPUM (crown-reinforcing) and/or the face horizontal reinforcing. In this study, therefore, the behavior of cohesionless soil around the face reinforced by the reinforcing member representing the RPUM and horizontal reinforcing is investigated through two-dimensional laboratory model tests. A series of tests were carried out on various conditions by changing lengths and angles of the reinforcing members. Based on the vertical pressure around the face, the characteristics of longitudinal arching have been found for the case of the non-reinforced and the reinforced.

• Korean Journal of Construction Engineering and Management
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• v.25 no.1
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• pp.32-41
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• 2024

In the construction industry, not only safety accidents, but also various complex risks such as construction delays, cost increases, and environmental pollution occur, and management technologies are needed to solve them. Among them, process risk management, which directly affects the project, lacks related information compared to its importance. This study tried to develop a MATM tunnel process risk classification system to solve the difficulty of risk information retrieval due to the use of different classification systems for each project. Risk collection used existing literature review and experience mining techniques, and DB construction utilized the concept of natural language processing. For the structure of the classification system, the existing WBS structure was adopted in consideration of compatibility of data, and an RBS linked to the work species of the WBS was established. As a result of the research, a risk classification system was completed that easily identifies risks by work type and intuitively reveals risk characteristics and risk factors linked to risks. As a result of verifying the usability of the established classification system, it was found that the classification system was effective as risks and risk factors for each work type were easily identified by user input of keywords. Through this study, it is expected to contribute to preventing an increase in cost and construction period by identifying risks according to work types in advance when planning and designing NATM tunnels and establishing countermeasures suitable for those factors.

• Journal of the Korean Geotechnical Society
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• v.40 no.2
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• pp.55-64
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• 2024

While shield tunneling has demonstrated stability in international cases, the new Austrian tunneling method (NATM) encounters challenges in urban environments with shallow cover, weathered ground, and high groundwater levels. This paper introduces two typical collapse scenarios observed in urban areas, specifically within weathered bedrock and uncemented sandy soil layers. The collapses are analyzed using six stability evaluation methods, and the results are synthesized to assess the excavation face stability through a hexagonal diagram. The study finds a consistent agreement between the analysis results of the two collapsed tunnel sites and the evaluation outcomes. The employment of the stability evaluation diagram, a comprehensive method that considers the ground characteristics of the target tunnel, proves crucial for ensuring barrier stability during the tunnel design stage. This method is essential for a holistic evaluation, especially when addressing challenging ground conditions in urban settings.

• Korean Journal of Construction Engineering and Management
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• v.19 no.6
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• pp.86-93
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• 2018

Infrastructure which mandatory in human life causes large environmental loads when they are being installed and maintained. Especially, maintenance is performed over a long period of time. Also, there is a limit to suggest a reliable estimated value because environmental loads are changed according to methods of maintenance and periods. In this study, we developed a Environmental Load Estimating Model to evaluate value and plan as soon as possible in the Early Design Phases while maintaining a tunnel. To estimate environmental loads by using brief design information, we analyze a calculation methodology of environmental loads in maintenance phases. Furthermore, we apply periods of maintenance work and maintenance factors considered a characteristic of long-term maintenance. Finally, a main purpose is that this program makes all users estimate environmental loads in maintenance phases easily and quickly. Accordingly, it is considered that the Environmental Load Estimating Model offer assistance to eco-friendly maintenance of the road and tunnel construction.

• Tunnel and Underground Space
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• v.8 no.2
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• pp.87-95
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• 1998

Field instrumentation and numerical analysis by the finite difference method were applied to estimate the relaxed zone in a subway tunnel of shallow depth in soft rock, excavated by NATM. The convergence and ground displacement can be used to estimate the deformation behavior and the relaxed zone. Parameters for the several models previously suggested were measured using regression analysis techniques adopting a function of time and the face advance. The estimated relaxed zone by the MPBX and FDM analysis were 1.5~3.0 m and 1.5~2.0 m, respectively. It was concluded that the visco-elastic model and the time-dependent elasto-plastic model correlate very well ($r^2$>0.9) with results of the numerical analyses.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2005.03a
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• pp.15-27
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• 2005

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.03a
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• pp.203-216
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• 2008

• Magazine of korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.44-60
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• 2012

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.652-654
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• 2007

• Journal of the Korea Construction Safety Engineering Association
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• s.45
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• pp.60-70
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• 2008

Mechanized tunnelling by TBMs has been extensively adopted for last two decades. Nevertheless, only few case histories have been reported. Unlike NATM tunnels, the case histories of the weak zone have been seldom reported for the mechanized tunnelling, even in the other countries. In this study, a collapse of TBM tunnel occurred in the severely altered weak rock zones between volcaniclastic rocks and granitic rocks was briefly described. A systematic geotechnical investigation, which was performed to examine the cause of the collapse, was carried out at the site and then characteristics of the rocks in the zones were evaluated. Moreover, This study propose a guide line of estimateing the possibility of collapse in TBM tunnels through comparing experimental results with surveying results of general rocks.