• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.144-150
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• 2006

The purpose of this study is to predict outlet temperature and humidity through underground pit for the reduction of cooling load and heating load. Commonly, the underground temperature is lower than outdoor in summer but the reverse happens in winter. When the outdoor average air temperature is $25.7^{\circ}C$ during cooling periods, the average outlet air temperature through underground pit is $23.6^{\circ}C$ with 3 m-depth and 60m-length and is $22.2^{\circ}C$ with 3 m-depth and 150 m-length. When the outdoor average air temperature is $4.9^{\circ}C$ during heating periods, the average outlet air temperature through underground pit is $7.7^{\circ}C$ with 3m-depth and 60 m-length and is $10.8^{\circ}C$ with 3 m-depth and 150 m-length. The outlet air temperature is affected by more length than depth of underground pit. The diffusion ratio of outdoor humidity is $-7.7\times10^{-8}kg/s$ in cooling periods and $9.29\times10^{-7}kg/s$ in heating periods.

• Journal of Power System Engineering
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• v.2 no.3
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• pp.27-33
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• 1998

The room temperature and air conditioning load in the underground space have been investigated numerically by the unsteady heat conduction equation. The model room has 3 m in height and 10 m in width, and it's position in the underground depth are 0.5 m to 5 m. When the room was located around surface, the room temperatures were strongly influenced by the atmosphere. But the underground depth is more than 2 m, the yearly temperature amplitude was small and the temperature phase was delayed. Up to 5 m of the depth, the cooling and heating load was decreased rapidly, but over 10 m of the depth, the air conditioning load was constant.

• Computers and Concrete
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• v.27 no.1
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• pp.1-12
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• 2021

This work presents a safety assessment of an underground tunnel subjected to a ballistic missile attack employing the numerical approach. For the impact simulation, a box shaped reinforced concrete (RC) structure with a cross section dimension of 8.0×10.0 m under a soil layer that was attacked by a SCUD missile was modeled using finite element (FE) software LS-DYNA. SCUD missile is one of a series of tactical ballistic missiles developed by Soviet Union during the Cold War, which is adopted for a short-range ballistic missile. The developed FE simulation for the penetration depth of the missile impacting into the soil structure was verified from the well-known formula of the penetration prediction. The soil-structure interaction, the soil type, and the impact missile velocity effects on the penetration depth of the missile into the different soil types were investigated. The safety assessment of the underground tunnel was performed with regard to the different depths of the underground tunnel. For each missile velocity and soil type, a specific depth called the unsafe depth was obtained from the analysis results. The structure beneath the soil beyond this depth remains safe. The unsafe depth was found to be increased with the increasing missile velocity.

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.69-83
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• 2005

In many cases, underground structures are built using conventional above-grade structural systems to carry gravity load. This paper proposes the use of underground arches, termed "buried arches", to support gravity loads, wherein the horizontal thrust of the arch is equilibrated by soil pressure. Because the horizontal soil pressure increases with depth, the depth of the arch may be reduced as the depth below grade increases. Critical to the success of such an approach is a proper accounting of creep and shrinkage for arches made of reinforced concrete. This paper addresses the influence of equilibrium, creep, and shrinkage as they affect the design of the arch from a theoretical perspective. Several examples illustrate the use of buried arches for the design of underground parking structures.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.315-322
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• 2001

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance for electric cables. In this paper, stress and strain of flexible pipes with various depth are calculated using traditional formula and FEM analysis. The results show that theoretical values are more conservative in strain whereas FEM analysis gives larger stress. Considering the strain criteria - 3.5 %, maximum, flexible pipes can be buried at the range of 50cm to 5m in depth without additional soil improvement.

• Journal of the Korean Professional Engineers Association
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• v.44 no.1
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• pp.44-47
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• 2011

Huge amount of energy produced by an underground nuclear test is released into the surrounding rock. Depending on the properties of the bed rock surrounding the detonation and overlaying it a variety of effects can occur. At some particular depth the increasing amount of material thrown upward is exactly balanced by the decreasing fraction escaping the crater, the crater volume reaches to a maximum. This depth is called the optimum depth of burial and varies somewhat with the geology of the site, being greater for less dense and structurally weaker material.

• Magazine of korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.86-94
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• 2002

• Fire Science and Engineering
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• v.30 no.2
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• pp.81-86
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• 2016

Recently, frequent traffic congestion has occurred in domestic urban roads. As a solution for downtown traffic congestion in domestic urban roads, plans for great depth underground double-deck tunnels have been made. Great depth underground double-deck tunnels that have been planned for passenger cars, has the structure of a network type; the entry of vehicles is carried out in the underground space. In these network great depth underground double-deck tunnels, the cross section and the height of the tunnel are smaller than the general road tunnel, and the smoke of a fire will propagate faster than the evacuation of tunnel passengers by the action of the traffic-ventilation and casualties are expected. Therefore, in the present study, an attempt was made to prevent the delay system for fire smoke diffusion at the time of a fire in a domestic network great depth underground double-deck tunnel according to the area of the tunnel block during the operation of the delay system for fire smoke diffusion to analyze the effects of reducing the inflow velocity. When the area of the tunnel block was not less than 50%, the effect of reducing about 21% of the wind speed acting on the tunnel was significant. If the area is more than 50%, the diffusion rate of fire smoke was reduced by approximately 21%, which will be useful for a safe evacuation.

• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.69-76
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• 2006

In this study, an experimental study in sand ground that was prepared by raining method was performed for modeling the bearing capacity behavior of strip footing above a cavity. The critical range of bearing capacity of the strip footing affected by underground cavity was investigated by comparing results between experiment and theory. The size of the critical region depends on several factors such as footing shape, soil property, cavity size and cavity shape. The ultimate bearing capacity was more influenced by the depth of the underground cavity than the eccentricity of the underground. In addition, an underground cavity influences on not only the decrease of the bearing capacity, but also the differential settlement of a strip footing.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.225-234
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• 2018

Domestic urban areas are experiencing serious traffic congestion problems due to continuous population growth and increased traffic volume. In order to solve the problem of traffic congestion, the study of great depth underground double deck tunnels using underground space is being actively carried out in the urban areas. The characteristics of great depth underground double deck tunnels are low in cross section, so the spread of fire smoke is expected to spread faster than the road tunnel in case of fire. Therefore, it is necessary to provide a fire smoke delay device which delays the spread of fire smoke when a fire occurs in a tunnels. In the previous study, the diffusion effect was analyzed according to the blocking area when the fire smoke spread delay device was operated through the 3D CFD in the study of preventing the smoke spread in the case of the tunnel fire. A study on fire smoke diffusion delay device using spring elasticity which is excellent in applicability to a tunnel and economical value is studied. In this study, fire smoke spread delay system was developed to fire smoke delay was experimentally analyzed. Fire smoke delay effect of fire smoke delay device appeared. Therefore, it is considered that the can minimize the damage of the victims when installed in the great depth underground double deck tunnels.