• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.4
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• pp.315-326
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• 2024

In this study, the Delphi method and AHP (analytic hierarchy process) were used to evaluate tunnel collapse risk from a comprehensive and multifaceted perspective. Influence factors were established through literature reviews, previous studies, and brainstorming sessions with expert groups, resulting in the construction of five main classification systems. A panel of 21 experts was formed, and three rounds of Delphi surveys were conducted to prevent errors and biases in the expert judgment process, thereby enhancing reliability. Ultimately, 14 influence factors were identified through CVR (content validity ratio) and COV (coefficient of variation) analyses of the experts' responses. Subsequently, the AHP method was applied to assess the relative importance of each influence factor and calculate the final composite weights. The timing of support and reinforcement had the highest priority, followed by groundwater inflow, joint conditions, support pattern levels, and auxiliary methods. These findings help identify the key factors affecting tunnel collapse risk and provide a foundation for developing strategies to improve tunnel safety.

• Geotechnical Engineering
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• v.38 no.3
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• pp.27-43
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• 2022

• Geotechnical Engineering
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• v.38 no.5
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• pp.9-30
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• 2022

• Geotechnical Engineering
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• v.39 no.1
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• pp.11-36
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• 2023

• Geotechnical Engineering
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• v.39 no.2
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• pp.9-34
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• 2023

• Geotechnical Engineering
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• v.39 no.6
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• pp.25-54
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• 2023

• Magazine of korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.21-45
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• 2024

• Geotechnical Engineering
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• v.40 no.1
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• pp.8-35
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• 2024

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1299-1306
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• 2005

The introduction of geodetic methods of absolute displacement monitoring in tunnels has improved the value of the measurements significantly. By using this method, structurally controlled behavior and influences of an anisotropic rock mass can be determined and the excavation and support adjusted accordingly. In this study cases of tunnel monitoring in anisotropic/heterogeneous rock masses are analyzed, and various anisotrpic behavior of tunnel can be estimated. Because rock anisotropy and heterogeneity can have great influence on tunnel behavior, tunnel design considering rock anisotropy and heterogeneity is needed. Also under construction, feedback must be performed by using face mapping and monitoring to prevent over-deformation and tunnel collapse.

• Journal of the Korean Geosynthetics Society
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• v.15 no.2
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• pp.55-64
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• 2016

The construction of the road NATM tunnel, which undergoes the weathered zone of the mountain, was in process with the reinforcement methods such as the rock bolt, shotcrete depositing, and the multi step grout with large diameter steel pipe. The collapse from the ceiling, and on the ground surface area(sink hole), of which were measured to be 25m from the ground surface($V=12m(W){\times}14m(L){\times}5m(H)=840m^3$), as well as excessive displacements in the tunnel, had occurred. In order to execute the necessary reconstruction work, the causes of the surface collapses were inspected through the field investigation, in-situ tests, and numerical analysis. As a result, several proper solutions were suggested for both internal and external reinforcements for the tunnel. As a result of numerical analysis, the collapsed zone of the tunnel was reinforced up to 0.5D~1.0D laterally by the cement grouting on the ground surface, 0.5D longitudinally by the multi step grout with large diameter steel pipe in tunnel. With further reinforcement implemented by rebars in lining, the forward horizontal boring was executed to the rest of the tunnel to evaluate the overall status of the tunnel face. Appropriate reinforcement methods were provided if needed.