• Geomechanics and Engineering
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• v.16 no.4
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• pp.341-353
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• 2018

A reinforced concrete pedestrian tunnel is constructed under a four-track surface railway. Heavy rainfall and soil exposure to drying lead to soil with different water content throughout the year. A railway is an open utility that is subject to rainfall without control on the quantity of the water on it and when there is a tunnel under a railway, the water content of the soil around the tunnel is very influential. This research shows the effects of change of water content in the soil around a pedestrian tunnel under a four-track surface railway. The pedestrian tunnel and the soil block around the tunnel are modeled in 3D by the FEM and are studied under the vibrations induced by the moving trains on the four-track surface railway for different soil water contents and the effects of the soil water content on the dynamic behavior of the tunnel and the surrounding soil are demonstrated.

• Tunnel and Underground Space
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• v.7 no.4
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• pp.274-283
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• 1997

It is necessary to estimate the soundness of tunnel using non-destructive tests(NDT) for effective repairs and maintenances. But, the state of tunnel lining could not be investigated using previous non-destructive techniques, due to the various types of support and accessibility only from one side in tunnel lining. Recently, the various non-destructive techniques such as ground penetrating radar(GPR) have been researched and developed for inspection of tunnel lining. In this study, the usefulness and applicability of GPR test in tunnel lining inspection has been investigated through model tests and tunnel site application. This paper described the tunnel lining inspection for lining thickness, cavity and support using GPR test. From the results of tests, we have concluded that GPR test are very useful and effective techniques to look into the interior of lining and measure the lining thickness.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.339-343
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• 2001

Shield tunnel having circular section located in the soil or soft rock layer is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately during earthquakes. Based on this knowledge, the ground-tunnel interaction effect for this particular vibration mode is investigated. The ground surrounding a tunnel is assumed to be a homogeneous elastic medium. The bonded boundary condition on the ground-tunnel interface is considered. This suggests a firm bond between the ground and the tunnel lining. As Poisson's ratio and stiffness of the ground increases, the strain induced within the tunnel lining increases.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.83-90
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• 2018

This paper describes a case study on the design factor analysis of vertical wind tunnel for skydiver's training or experiencing of paradropping exercise in the air. The case study of vertical wind tunnel design is to provide the knowledges on effects of parameter's variation when it is applied to overall or partial duct of tunnel circuit. The analysis of design parameters based on pressure loss are produced one by one through the tunnel components from the flight chamber because the wind tunnel must satisfy the requirement of flight chamber such as flow speed, quality and quantity. Results shows the various effects of parameter variation with pressure loss in the wind tunnel circuit. Pressure loss should be based on the determination of fan and power system which can be selected from market or new design.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.778-783
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• 2008

In this paper, numerical method was calculated on evaluation of underground ventilation system to keep servicing a fresh air. The tunnel length for simulation is 18.2 km with various located seven ventilation shaft. Generally, owing to thermal generation in cable tunnel under about 50 m depths, cable tunnel ventilation system is more important than that of other tunnels. So, we conducted that the effects of ventilation systems was simulated depending on the difference of electrical power tunnel length, the number of shaft tunnel, forced ventilation and duct was or not. Test results show that the main conditions in order to enhance the underground cable tunnel are that ventilation systems have to be designed with forced ventilation and with duct.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.292-298
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• 2005

Tunnel in subway should be designed as a water-proof type tunnel as much as possible but it is difficult to make it come true due to several facts, such as construction technique and cost. A drainage type tunnel as a substitute of a water-proof tunnel lead to the increase of water pressure on the concrete lining that make bad effect to tunnel structure when it has some problem to operate the drainage system. Throughout studying about cases on defects of tunnel drainage in subway We hope it contributes to tunnel maintenance.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.911-917
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• 2018

This paper concerns a numerical investigation on the effect of construction sequence on three-arch (3-Arch) tunnel behavior. A three-arch tunnel section adopted in a railway tunnel construction site was considered in this study. A calibrated 3D finite element model was used to conduct a parametric study on a variety of construction scenarios. The results of analyses were examined in terms of tunnel and ground surface settlements, shotcrete lining stresses, loads and stresses developed in center column in relation to the tunnel construction sequence. In particular, the effect of the side tunnel construction sequence on the structural performance of the center structure was fully examined. The results indicated that the load, thus stress, in the center structure can be smaller when excavating two side tunnels from opposite direction than excavating in the same direction. Also revealed was that no face lagging distance between the two side tunnels impose less ground load to the center structure. Fundamental governing mechanism of three-arch tunnel behavior is also discussed based on the results.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.3
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• pp.261-268
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• 2003

Terzaghi's tunnel theory has been accepted to calculate tunnel loads conservatively in practical design until now. In this study, Terzaghi's tunnel theory was expanded to the inclined-layer ground with inclination of ground and stratification. Finally a new tunnel load equation was induced utilizing the original Terzaghi's tunnel theory and Terzaghi's tunnel theory was reviewed as well.

• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.89-96
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• 2000

In this study, experiments were performed for various drying air temperatures, air flow rates tray distance to analyze drying characteristics of batch type tunnel dryer. In comparison of tunnel drying with cabinet drying which is currently used in the farm, the results of drying simulation model of cabinet dryer was used and then the possibility of applying the drying simulation model of cabinet dryer to batch type tunnel dryer was investigated. The results showed that as the drying temperature increased, the drying rte and moisture difference in the direction of air flow increased and as the air flow rate increased, the drying rate increased and moisture differences decreased. In tunnel dryer, drying through bottom of the tray had large effect on drying rate and the effect was more significant when the drying temperature increased. As air flow rate increased, the difference of drying rates between tunnel and cabinet drying increased and drying rate of tunnel of drying was higher. The drying simulation model could estimate moisture content in tunnel more precisely by using modified effective moisture diffusion coefficient for air flow rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.838-844
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• 2004

In a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution below the required level. To develop control algorithms for a tunnel ventilation system, a dynamic simulation program may be used to predict the pollution level in a tunnel. Research was carried out to develop better pollution models for a tunnel ventilation control system. A neural network structure was adopted and compared by using actual poilution data. Simulation results showed that the dynamic model developed by a neural network may be effective for the development of tunnel ventilation control algorithms.