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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Tunnelling and Underground Space Association
Journal Basic Information
Journal DOI :
Korean Tunnelling and Underground Space Association (KTA)
Editor in Chief :
Volume & Issues
Volume 8, Issue 4 - Dec 2006
Volume 8, Issue 3 - Sep 2006
Volume 8, Issue 2 - Jun 2006
Volume 8, Issue 1 - Mar 2006
Selecting the target year
Effects of Excavation Methods on Tunnel Deformation Behavior - A Numerical Investigation
Yoo, Chung-Sik ; Kim, Joo-Mi ; Kim, Sun-Bin ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 289~305
This paper presents the effect of excavating methods on tunnel behavior. As part of this study, it is preliminarily focused on the comparison of two different excavation methods, center diaphram (CD) method and ringcut (RC) method. Especially, the purpose of this research is to study the behavioral mechanism of two tunnels which share the same construction environment but different excavating method. Two numerical analysis models with the same tunnel section and material properties are compared in this study, and they are analyzed by 3D finite element analysis. In each model, face stability, crown displacement, ground settlement, and shotcrete-lining stress are computed, then the general behavior of CD method and RC method is studied. The results indicate that the CD method tends to be effective in controlling tunnel displacement while the RC method is more effective in controlling ground settlement. Design implications of the findings from this study are discussed.
Effects of Tunnel Construction on an Existing Tunnel Lining
Yoo, Chung-Sik ; Song, Ah-Ran ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 307~324
Effects of new tunnel construction on an existing tunnel are investigated in this paper. A parametric study was conducted on a number of conditions in terms of relative location of the new tunnel to the existing tunnel using 2D and 3D finite element models. The results indicated that the new tunnel construction imposes most severe effect on the existing tunnel's lining when located below the existing tunnel's springline for cases in which the new tunnel is constructed parallel to the existing tunnel. It is also revealed that the effect to the new tunnel construction is larger when the new tunnel is constructed under the existing tunnel than above for cases in which the new tunnel is crossed with the existing tunnel. Practical implications of the finding are discussed.
The Effects of Tunnel Geometrical Characteristics and Canopy Installation on the Ventilation and Fire Propagation
Lee, Chang-Woo ; Suh, Ki-Yoon ; Kim, Jung-Wook ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 325~334
Understanding the airflow characteristics within the canopy structure installed between closely adjacent tunnels either for light adaptation or for protection from snow hazards is required for the normal ventilation as well as safety system design. Grade, horizontal alignment, cross-sectional area and shape are known to substantially influence the fire smoke behavior and their influences raise great concern for the safety design. This paper aims at studying the effects of tunnel geometrical characteristics and canopy installation on the ventilation and fire propagation through CFD analysis. In the case of 145m long canopy, 50% opening ratio is preferred with respect to the airflow pattern and ventilation efficiency. When a 20MW fire occurs in a 1.8km-long tunnel and four 1250mm reversible jet fans are instantly turned on, smoke concentration at 40m downstream of the fire decrease 13% for the upgrade tunnel with 2% gradient and increases 20% for -2% gradient, compared to the standard horizontal tunnel. Backlayering is observed within 45m-long segment toward the entrance in 2% down-graded tunnel. In a rectangular tunnel, there is no significant difference of smoke concentration as well as velocity profile from the standard crown tunnel. Three-laned tunnel shows lower level of both profiles and backlayering is detected up to 50m upstream of the fire, while the risky situation rapidly disappears thereafter.
Model Test for the Determination of Distances between Jet-fans and Analysis of Recirculation
Kweon, Oh-Sang ; Yoon, Chan-Hoon ; Yoon, Sung-Wook ; Kim, Jin ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 335~344
The domestic standards which used the standards of Road Association of Japan standards presents the distances of between jet-fans by the caliber of jet-fan. However, the Permanent International Association of Road Congress (PIARC) encourages it to be ten times a diameter of the tunnel. The distance of jet-fans installed in bases of two standards differs as much as two times, as so the proper basis after analysis of internal air current is needed since such difference can lead to disadvantage for selection of ventilation configuration. Based on Froude modeling theory, 1/40 scale acrylic model of a tunnel (215mm in diameter and 6.9m in length) and jet-fan (26.3mm and 31.6mm in caliber) was made for the measurement of changes in pressure and velocity due to the extension of tunnel for analysis of internal air current. And we measured the changes in pressure of surroundings of a jet-fan for confirmation of recirculation due to the exterior airs when the jet-fan is on. The results of the model test show that internal air current was not influenced by the caliber of jet-fan and its changes in pressure and velocity were stable in the point where it was nine times of diameter of the tunnel. Also the recirculation when the jet-fan is on could be verified. According to such results, in the cases of installing jet-fan in tunnels, the distances between jet-fans needs to be more than nine times the diameter.
A Laboratory Test and Numerical Analysis to Determine the Number of Additional Installation of Face Bolts due to the Deviated Bolts from the Horizontal Direction
Seo, Kyoung-Won ; Lee, Sung-Won ; Kim, Chang-Yong ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 345~354
During installation of face bolts, they are often deviated from the designed horizontal direction. In this study, a laboratory test and numerical analysis were conducted to examine the change of support effect by them. Also, the number of bolts to be added for achieving the designed support effect was considered. It was verified in this study that the horizontal installation is more effective. Under the test condition of this study, 1.5 bolts/section should be added in the face of which the installation density was 3 bolts/section when the bolts were installed with
angle from the horizontal position.
Influence of Pore Pressure Behind a Subsea Tunnel on Its Stability
You, Kwang-Ho ; Lee, Kwang-Hoon ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 355~363
In this study, it was analyzed how the pore pressure behind a subsea tunnel influences on the stability of the tunnel. The tunnel is located in the soft rock layer, and a soft sandy layer and weathered soil layer are located on the top of it. Coupled numerical analyses are performed for both drained and undrained condition with varying coefficients of lateral earth pressure. In the case of undrained conditions, the stability of the tunnel was analyzed with different thicknesses of shotcrete. On the other hand, a sensitivity analysis was performed with different hydraulic conductivities and porosities of the shotcrete for the drained conditions. The stability of a subsea tunnel was evaluated in terms of safety factor suggested by You et al.(2000, 2001, 2005) based on the shear strength reduction technique. In this paper, the safety factor of a tunnel was calculated under steady state flow condition during hydro-mechanical coupled analysis. As a result, it was found that the stability of a subsea tunnel could be rather increased by allowing a proper amount of groundwater inflow into a subsea tunnel.
A Study on Secondary Lining Design of Tunnels Using Ground-Lining Interaction Model
Chang, Seok-Bue ; Huh, Do-Hak ; Moon, Hyun-Koo ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 365~375
The structural analysis for the secondary lining of tunnels is generally performed by a frame analysis model. This model requires a ground loosening load estimated by some empirical methods, but the load is likely to be subjective and too large. The ground load acting on the secondary lining is due to the loss of the supporting function of the first support members such as shotcrete and rockbolts. Therefore, the equilibrium condition of the ground and the first support members should be considered to estimate the ground load acting on the secondary lining. Ground-lining interaction model, shortly GLI model, is developed on the basis of the concept that the secondary lining supports the ground deformation triggered by the loss of the support capacity of the first support members. Accordingly, the GLI model can take into account the ground load reflecting effectively not only the complex ground conditions but the installed conditions of the first support members. The load acting on the secondary lining besides the ground load includes the groundwater pressure and earthquake load. For the structural reinforcement of the secondary lining based on the ultimate strength design method, the factored load and various load combination should be considered. Since the GLI model has difficulty in dealing with the factored load, introduced in this study is the superposition principle in which the section moment and force of the secondary lining estimated for individual loads are multiplied by the load factors. Finally, the design method of the secondary lining using the GLI model is applied to the case of a shallow subway tunnel.
Development of a 3D Laser Scanner Based Tunnel Scanner
SaGong, Myung ; Moon, Chul-Yi ; Lee, Jun-S. ; Hwang, Seon-Keun ; Kim, Byung-Hong ;
Journal of Korean Tunnelling and Underground Space Association, volume 8, issue 4, 2006, Pages 377~388
Most structures experience deterioration after construction. A routine inspection and maintenance must be accomplished for the efficient use of the structures. The routine inspection will play a major role on the determination of maintenance period and method. This study aims development of an automated tunnel inspection system based upon a 3 dimensional laser scanner. As for the initial stage of the project, a prototype tunnel scanner has been developed. The development of a tunnel scanner prototype follows comparison between image scanning and laser scanning system and investigation on the applicability and adaptivity of the scanners to the railway tunnel scanner. The applicability of the laser scanner on the railway tunnel has been confirmed from the pilot test by using commercialized general purpose close range laser scanner and applicability of a laser scanner as a railway tunnel scanner has been checked. From the result, a prototype of railway tunnel scanner has been built and the calibration of the system was carried out. Finally the developed tunnel laser scanner has been applied to different shapes and sizes of tunnels in use.