• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1845-1850
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• 2003

The underground utility tunnels are important facility as a mainstay of country because of communication developments. The communication and electrical duct banks as well as various utility lines for urban life are installed in the underground utility tunnel systems. If a fire breaks out in this life-line tunnel, the function of the city will be discontinued and the huge damages are occurred. In order to improve the safety of life-line tunnel systems and the fire detection, the behaviors of the fire-induced smoke flow and temperature distribution are investigated. In this study we assumed that the fire is occurred at the contact or connection points of cable. Numerical calculations are carried out using different velocity of ventilation in utility tunnel. The fire source is modeled as a volumetric heat source. Three-dimensional flow and thermal characteristics in the underground tunnel are solved by means of FVM (Finite Volume Method) using SIMPLE algorithm and standard ${\kappa}-{\varepsilon}$ model for Reynolds stress terms. The numerical results of the fire-induced flow characteristics in an underground utility tunnel with different velocity of ventilation are graphically prepared and discussed.

• Magazine of korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.49-57
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• 2021

• Journal of the Korean Geotechnical Society
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• v.37 no.12
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• pp.7-23
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• 2021

Underground utility tunnels, which contribute to supply of electricity, communication, water and heat, are critical lifelines of an urban area. In case service is discontinued or functional disruption happens, there will be a huge socio-economic impact. For the improved seismic design and evaluation of underground structures, this study proposes a ground displacement measure when the site is subjected to a scenario earthquake based on hazard-consistent source spectra and site amplification/attenuation. This measure provides a rational estimation of ground displacement and can be an alternative to existing response displacement methods.

• Computers and Concrete
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• v.27 no.2
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• pp.163-173
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• 2021

In this paper, the parameters of haunch height, reinforcement ratio and site condition were evaluated for the influence on the seismic performance of a composite precast fabricated utility tunnel by shaking table test and numerical simulation. The dynamic response laws of acceleration, interlayer displacement and steel strain under unidirectional horizontal seismic excitation were analyzed through four specimens with a similarity ratio of 1:6 in the test. And a numerical model was established and analyzed by the finite element software ABAQUS based on the structure of utility tunnel. The results indicated that composite precast fabricated utility tunnel with the good anti-seismic performance. In a certain range, increasing the height of haunch or the ratio of reinforcement could reduce the influence of seismic wave on the utility tunnel structure, which was beneficial to the structure earthquake resistance. The clay field containing the interlayer of liquefied sandy soil has a certain damping effect on the structure of the utility tunnel, and the displacement response could be reduced by 14.1%. Under the excitation of strong earthquake, the reinforcement strain at the side wall upper end and haunches of the utility tunnel was the biggest, which is the key part of the structure. The experimental results were in good agreement with the fitting results, and the results could provide a reference value for the anti-seismic design and application of composite precast fabricated utility tunnel.

• Journal of the Korean Geotechnical Society
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• v.38 no.12
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• pp.29-43
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• 2022

Various underground facilities are being constructed to improve the urban environment. Therefore, it is more necessary than ever to reasonably evaluate the seismic response of underground utility tunnels, playing a significant part in urban infrastructure. In this study, the major features and differences of two types of existing pseudo-static analysis methods are reviewed. Each method uses a simplified 2D frame model to represent the seismic behavior of underground structures. Applying each method to a one-barrel rectangular utility tunnel in Korea, the suitability in predicting seismic responses, especially the racking deformation of the tunnel, is examined. In addition, several precautions and suggestions are provided in this study against the inattentive application of the methods to seismic evaluation of underground structures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.931-946
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• 2018

In line with the increased usability of utility pipe conduits in urban areas, construction and R&D activities of utility tunnel, incorporated with the shield TBM method, are actively under way. The utility tunnels are installed through underground excavation, and thus are relatively weak in terms of construction safety. However, hazards associated with the utility tunnel construction have not been properly identified, despite the introduction of a policy to the 'Design for Safety' for the purpose of reducing accident rates in the construction industry. Therefore, in this study, following the derivation of hazards associated with utility tunnel, these hazards were then used as the basis to uncover key safety hazards requiring extensive management in a field, which were then used to conduct a risk assessment having applied the matrix method so that the results can be utilized in risk assessment during the stages of utility tunnel planning, design, and construction, while also serving as a data reference.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.111-120
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• 2012

PURPOSES : This study is to suggest suitable lighting facility installation plans by finding out driver's preference for combination of lighting facility installation among landscape factors that affect driver visibility in tunnels. METHODS : SD method is used to extract emotional factors that affect drivers' preference, Components of tunnel lighting facility installation are evaluated through conjoint analysis and it suggested relative importance of attributes and utility values. RESULTS : In the aspects of satisfaction levels of components of tunnel lighting facility installation, Tunnel side, two lows, and solid line arrangement type has the highest level of satisfaction. Extract emotional factors that affect drivers' preference are "safety", "openness" and "amenity." In addition, the result of analyzing relative importance of attributes of tunnel lighting facility shows that numbers of lighting array has the highest importance and lighting facility arrangement has the lowest importance. Result of analyzing partial utility shows that the 2 low type among number of lows, the solid line arrangement type between arrangement types, placing in the middle part among lighting facility arrangement were highly preferred. CONCLUSIONS : In the case of lighting numbers, utility values of the first line and the second line showed us a big difference. Increasing the number arrays in the future reformation of lighting facility installation combination will be effective in enhancing the utility of the driver.

• Computers and Concrete
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• v.29 no.2
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• pp.69-79
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• 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.111-118
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• 2014

While large-sized facilities (type I II) have been managed systematically after the establishment of the Special Law for Safety Management on Facility, the management of small-sized facilities is relatively poor. The small-sized facilities have been managed by The Basic Law for Disaster and Safety Management, however, it is hard to manage them systematically as related standards are not established. Therefore, this study proposed the management plans for including the facilities such as some road tunnels and utility tunnels, which have the definite manager and a high possibility to harm the public, into type I and II facilities. In addition, it proposed the reinforcement plans of safety management for small-sized and vulnerable facilities such as breast wall and cut slopes, traditional markets and pedestrian bridges, which are fundamental facilities closely related to people's life, although a budget and a man-power are not enough.

• Earthquakes and Structures
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• v.17 no.2
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• pp.233-244
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• 2019

In this work, we have studied the effects of different soil thicknesses, haunch heights, reinforcement forms and construction technologies on the seismic performance of a composite precast fabricated utility tunnel by pseudo-static tests. Five concrete specimens were designed and fabricated for low-cycle reciprocating load tests. The hysteretic behavior of composite precast fabricated utility tunnel under simulated seismic waves and the strain law of steel bars were analyzed. Test results showed that composite precast fabricated utility tunnel met the requirements of current codes and had good anti-seismic performance. The use of a closed integral arrangement of steel bars inside utility tunnel structure as well as diagonal reinforcement bars at its haunches improved the integrity of the whole structure and increased the bearing capacity of the structure by about 1.5%. Increasing the thickness of covering soil within a certain range was beneficial to the earthquake resistance of the structure, and the energy consumption was increased by 10%. Increasing haunch height within a certain range increased the bearing capacity of the structure by up to about 19% and energy consumption by up to 30%. The specimen with the lowest haunch height showed strong structural deformation with ductility coefficient of 4.93. It was found that the interfaces of haunches, post-casting self-compacting concrete, and prefabricated parts were the weak points of utility tunnel structures. Combining the failure phenomena of test structures with their related codes, we proposed improvement measures for construction technology, which could provide a reference for the construction and design of practical projects.