• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.2
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• pp.61-76
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• 2021

As the number of existing road tunnels increases every year, collapse and floor heaving accidents occur frequently during construction. The collapse among tunnel accidents dominates, so that studies related to the floor heaving are relatively insufficient. Accordingly, many studies to reinforce the lower part of the tunnel have been conducted, but the analysis on the effect of the curvature of the tunnel floor is insufficient. Therefore, in this study, the effects of the upper analysis area height and the coefficient of lateral earth pressure of the tunnel located on a tuff deterioration zone with a large rock cover, as well as the floor curvature, were examined through sensitivity analysis. As a result of the analysis, it turned out that the overall stability of the tunnel increases as the floor curvature increases, the coefficient of lateral earth pressure decreases, and the upper analysis region increases.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.887-895
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• 2019

Recently, the number of underground road development projects has been increasing to solve traffic problems in the national capital region and metropolitan areas with intensified overcrowding, and there has been a tendency to plan underground roads by applying a double-deck tunnel technology that has advantages in constructability and economical efficiency. The double-deck tunnel has a structure where one excavation section is divided into two parts and used as up and down lines, and is mainly used as a road for small vehicles only due to its low floor height. In addition, due to the small cross-sectional area, it has characteristics different from those of general road tunnels in terms of ventilation and disaster prevention. In this regard, this study proposed an operational plan that applies an oversized exhaust system, which is one of semi-transverse ventilation systems, to small cross-sectional tunnels like double-deck tunnel with low floor height, and a comparative analysis between smoke exhaust characteristics according to the fire occurrence locations and oversized exhaust systems was conducted using the Fire Dynamics Simulator (FDS). The results showed that unlike uniform exhaust, intensive smoke exhaust using the oversized exhaust port maximized the delay effect of smoke diffusion and limited the smoke within 50 m above and below the fire point.