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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)
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Volume & Issues
Volume 14, Issue 6 - Nov 2012
Volume 14, Issue 5 - Sep 2012
Volume 14, Issue 4 - Jul 2012
Volume 14, Issue 3 - May 2012
Volume 14, Issue 2 - Mar 2012
Volume 14, Issue 1 - Jan 2012
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Shear behavior at the interface between particle and non-crushing surface by using PFC
Kim, Eun-Kyung ; Lee, Jeong-Hark ; Lee, Seok-Won ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 293~308
DOI : 10.9711/KTAJ.2012.14.4.293
The shear behavior at the particle/surface interface such as rock joint can determine the mechanical behavior of whole structure. Therefore, a fundamental understanding of the mechanisms governing its behavior and accurately estimation of the interface strength is essential. In this paper, PFC, a numerical analysis program of discrete element method was used to investigate the effects of the surface roughness on interface strength. The surface roughness was characterized by smooth, intermediate, and rough surface, respectively. In order to investigate the effects of particle shape and crushing on particle/surface interface behavior, one ball, clump, and cluster models were created and their results were compared. The shape of particle was characterized by circle, triangle, square, and rectangle, respectively. The results showed that as the surface roughness increases, interface strength and friction angle increase and the void ratio increases. The one ball model with smooth surface shows lower interface strength and friction angle than the clump model with irregular surface. In addition, a cluster model has less interface strength and friction angle than the clump model. The failure envelope of the cluster model shows non-linear characteristic. From these findings, it is verified that the surface roughness and particle shape effect on the particle/surface interface shear behavior.
Dynamic Behaviors of the Curved Steel Tunnel Lining due to Wind Loads by Passing Vehicles
Mha, Ho-Seong ; Cho, Kwang-Il ; Park, Inn-Joon ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 309~320
DOI : 10.9711/KTAJ.2012.14.4.309
Dynamic behaviors of the tunnel linings of curved tunnels with various curvatures are investigated to examine the effect of wind loads due to passing vehicles. In the case without backfill, the responses of the tunnel lining should be considered to examine the clearance of the lining. A steel tunnel lining is selected to see the influence of the wind load upon the tunnel lining more clearly. The wind pressure upon the lining is simplified into the pressure and suction while the vehicle passing the loading positions. As the radius of curvature decreases, the response decreases, showing that the strength against the deformation is found to increase since the asymmetry of the deformation shape is reduced. It is found that the responses increase as the passing vehicle speed increases.
Surface roughness crushing effect on shear behavior using PFC
Kim, Eun-Kyung ; Jeong, Da-Woon ; Lee, Seok-Won ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 321~336
DOI : 10.9711/KTAJ.2012.14.4.321
The shear behavior at the particle/surface interface such as rock joint can determine the mechanical behavior of whole structure. Therefore, a fundamental understanding of the mechanisms governing its behavior and accurately estimation of the interface strength is essential. In this paper, PFC, a numerical analysis program of discrete element method was used to investigate the effects of the surface roughness crushing on interface strength. The surface roughness was characterized by smooth, intermediate, and rough surface, respectively. Particle shape was classified into one ball model of circular shape and 3 ball model of triangular shape. The surface shape was modelled by wall model of non-crushing surface and ball model of crushing surface. The results showed that as the bonding strength of ball model decreases, lower interface strength is induced. After the surface roughness crushing was occurred, the interface strength tended to converge and higher bonding strength induced lower surface roughness crushing. Higher friction angle was induced in wall model and higher surface roughness induced the higher friction angle. From these findings, it is verified that the surface roughness and surface roughness crushing effect on the particle/surface interface shear behavior.
Behaviour of single piles and pile groups in service to adjacent tunnelling conducted in the lateral direction of the piles
Lee, Cheol-Ju ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 337~356
DOI : 10.9711/KTAJ.2012.14.4.337
Three-dimensional (3D) numerical analyses have been performed to study the behaviour of single piles and grouped piles to adjacent tunnelling in the lateral direction of the pile. In the numerical analyses, the interaction between the tunnel, the pile and the soil next to the piles and shear transfer mechanism have been analysed allowing soil slip at the pile-soil interface by using interface elements. The study includes the shear stresses at the soil next to the pile, the axial force distributions on the pile and the pile settlement. It has been found that existing elastic solutions may not accurately estimate the pile behaviour since several key issues are excluded. Due to changes in the shear transfer between the pile and the soil next to the pile with tunnel advancement, the shear stresses and axial force distributions along the pile change drastically. Downward shear stress develops above the tunnel springline while upward shear stress is mobilised below the tunnel springline, resulting in a compressive force on the pile. In addition, mobilisation of shear strength at the pile-soil interface was found to be a key factor governing pile-soil-tunnelling interaction. It has been found that grouped piles are less influenced by the tunnelling than the single pile in terms of the axial pile forces. The reduction of apparent allowable pile capacity due to pile settlement resulted from the tunnelling seemed to be insignificant.
A tunnel back analysis using artificial neural network technique and face mapping data
You, Kwang-Ho ; Kim, Kyoung-Seok ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 357~374
DOI : 10.9711/KTAJ.2012.14.4.357
Considerable uncertainties are included in ground properties used for tunnel designs due to the limited investigation and tests. In this study, a back analysis was performed to find optimal ground properties based on artificial neural network using both face mapping data and convergence measurement data. First of all, the rock class of a study tunnel is determined from face mapping data. Then the possible ranges of ground properties were selected for each rock class through a literature review on the previous studies and utilized to establish more precise learning data. To find an optimal training model, a sensitivity analysis was also conducted by varying the number of hidden layers and the number of nodes more minutely than the previous study. As a result of this study, more accurate ground properties could be obtained. Therefore it was confirmed that the accuracy of the results could be increased by making use of not only convergence measurement data but also face mapping data in tunnel back analyses using artificial neural network. In future, it is expected that the methodology suggested in this study can be used to estimate ground properties more precisely.
A Study on the development of a decision model on free flow and congested traffic conditions to determine the optimal ventilation capacity in highway tunnels
Kim, Hyo-Gyu ; Yoo, Ji-Oh ; Lee, Chang-Woo ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 375~395
DOI : 10.9711/KTAJ.2012.14.4.375
According to the local highway tunnel ventilation guideline, ventilation capacity calculation should be performed at the speed ranging from 10 km/h to 80 km/h. This is so reasonable method considering uncongested and congested traffic conditions in urban tunnels. But recently due to low traffic volume and very low congestion frequency in rural highway tunnels, it seems to be an inadequate way to apply the guideline. Therefore the calculation should be performed separately for the free flow and congested traffic cases classified by the appropriate decision model. This paper aims at determining unnecessary running speed range for reasonable tunnel ventilation design, considering free flow and congested traffic conditions. Firstly, traffic volumes in highway tunnels were collected and if any, the causes of congestion were investigated. And with concept of 'margin speed'(
), the decision model on traffic congestion was developed. Applicability of the decision model was also analyzed with case study. According to the results, when design speed is 100 km/h, with V/C less than 0.1, then the range of unnecessary speed in tunnel ventilation design is less than 40 km/h; for
, the unnecessary speed ranges are found to be
Development of pressurizing support tunneling method and case study of its field application
Kim, Dea-Young ; Lee, Hong-Sung ; Lee, Se-Jin ; Lee, Hee-Kwang ; Sim, Bo-Kyoung ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 397~419
DOI : 10.9711/KTAJ.2012.14.4.397
The pressurizing support tunneling method has been developed that overcomes shortcomings of conventional trenchless methods and applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies higher pressure than the pressure relaxed by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through 3D numerical analyses. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long ramp tunnel that passes under
Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months which decreases construction time to 35% compared to conventional methods, and ground displacement was almost negligible.
Effect of abrasive waterjet parameters on rock removal
Oh, Tae-Min ; Cho, Gye-Chun ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 421~435
DOI : 10.9711/KTAJ.2012.14.4.421
Rock excavation (removal) tests are performed with effective parameters using an abrasive waterjet. For verification of the field rock excavation capabilities, the removal performance and level of efficiency are analyzed for hard granite rock in terms of the water pressure, exposure time of the jet, and the standoff distance. In particular, experimental tests are performed with a long standoff distance required condition in the real excavation field. The rock removal performance level changes according to the rock properties. In this study, various rock specimens are used and P-wave velocities are measured in order to determine the correlation between the removal performance and the P-wave velocity. As a result of the experimental study, the effect of waterjet parameters on rock removal is analyzed.
Assessment of over / under-break of tunnel utilizing BIM and 3D laser scanner
Park, Jeong-Jun ; Shin, Jae-Chou ; Hwang, Ju-Hwan ; Lee, Kang-Hyun ; Seo, Hyung-Joon ; Lee, In-Mo ;
Journal of Korean Tunnelling and Underground Space Association, volume 14, issue 4, 2012, Pages 437~451
DOI : 10.9711/KTAJ.2012.14.4.437
Application of 3D laser scanner to civil engineering is widely studied in various fields such as tunnel, bridge, calculation of earth volume, construction measurement, observation of rock joint, etc. Some studies on utilization of the 3D laser scanner for calculating the over-break and/or under-break of tunnels have also been carried out. However, in the previous research, the scanning data were usually compared with the 2D CAD blueprint results; although the shape of tunnel structure is relatively simple, for precise calculation of the over-break and/or under-break of tunnels, three-dimensional analysis based on BIM is needed. Therefore, in this paper, a new program that calculates the over-break and/or under-break of tunnels using the 3D laser scanner and the BIM is developed; moreover the effective and rapid process of data treatment is proposed. The accuracy of the developed program was verified by applying the new system to a real tunnels construction field.