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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 15, Issue 6 - Nov 2013
Volume 15, Issue 5 - Sep 2013
Volume 15, Issue 4 - Jul 2013
Volume 15, Issue 3 - May 2013
Volume 15, Issue 2 - Mar 2013
Volume 15, Issue 1 - Jan 2013
Selecting the target year
Tensile strength evaluation of SFRC subjected to high temperature using double punch test
Moon, Do-Young ; Chang, Soo-Ho ; Bae, Gyu-Jin ; Lee, Gyu-Pil ; Kim, Hee-Sung ;
Journal of Korean Tunnelling and Underground Space Association, volume 15, issue 1, 2013, Pages 1~11
DOI : 10.9711/KTAJ.2013.15.1.001
Steel fiber-reinforced concrete (SFRC) is widely used for tunnel lining structure such as shot-crete in NATM tunnel and segment in TBM tunnel. In tunnel fire accidents, structural performance of a lining is very important because the lining is the structure that directly exposed to fire. In this study, the effects of high temperatures, mix ratios and types on failure pattern, DPT tensile strength and coefficient of variation were investigated through Double Punch Tests (DPT) of SFRC subjected to high temperatures. In the results, it is confirmed that the residual DPT tensile strength increases as for SFRC and this is more in SFRC with higher mix ratio. But, the equation for evaluation of DPT tensile strength does not involve the number of failure surfaces SFRC specimens subjected to high temperatures, therefore, it is required to investigate more fracture energy in DPT tests.
Stochastic numerical study on the propagation characteristics of P-Wave in heterogeneous ground
Song, Ki-Il ;
Journal of Korean Tunnelling and Underground Space Association, volume 15, issue 1, 2013, Pages 13~24
DOI : 10.9711/KTAJ.2013.15.1.013
Various elastic wave-based site investigation methods have been used to characterize subsurface ground because the dynamic properties can be correlated with various geotechnical parameters. Although the inherent spatial variability of the geotechnical parameters affects the P-wave propagation characteristics, ground heterogeneity has not been considered as an influential factor. Thus, the effect of heterogeneous ground on the travel-time shift and wavefront characteristics of elastic waves through stochastic numerical analyses is investigated in this study. The effects of the relative correlation lengths and relative propagation distances on the travel-time shift of P-waves considering various intensities of ground heterogeneity were investigated. Heterogeneous ground fields of stiffness (e.g., the coefficient of variation = 10 ~ 40%) were repeatedly realized in numerical finite difference grids using the turning band method. Monte Carlo simulations were undertaken to simulate P-wave propagation in heterogeneous ground using a finite difference method-based numerical approach. The results show that the disturbance of the wavefront becomes more significant with stronger heterogeneity and induces travel-time delays. The relative correlation lengths and propagation distances are systematically related to the travel-time shift.
A study on estimation of the total loss and damage ratio of maintenance monitoring sensor of subway tunnel
Woo, Jong-Tae ;
Journal of Korean Tunnelling and Underground Space Association, volume 15, issue 1, 2013, Pages 25~31
DOI : 10.9711/KTAJ.2013.15.1.025
In this study, the total loss and damage ratio of maintenance monitoring which is installed and operated in the domestic and foreign tunnel structure is researched and analyzed for estimating the loss and damage ratio of maintenance monitoring sensor of subway tunnel. The total loss and damage ratio at the elapsed time of 5-6 years after installation is 14.2% in the Seoul metro line no.5,6 and 7, 14.8% in the section 1 of the Seoul metro line no.9, 13.9% in the Channel tunnel of England and all of them are close to 15%. Therefore, it is reasonable to reflect that the total loss and damage ratio of maintenance monitoring sensor of subway tunnel is estimated provisionally 15% on design, and hence the study of the loss and damage ratio with the number of elapsed years in long-term by the measurement category will be needed.
Hauling time prediction of the muck generated by a blasting around a tunnel
You, Kwang-Ho ; Son, Myung-Kyun ;
Journal of Korean Tunnelling and Underground Space Association, volume 15, issue 1, 2013, Pages 33~47
DOI : 10.9711/KTAJ.2013.15.1.033
When a bomb explodes near a tunnel, generated muck should be quickly moved outside for rehabilitation of the tunnel. In this study, the amount of muck generated by an explosion was estimated and a methodology was presented for the prediction of the muck hauling time. To this end, 3D-meshes were made by using SoildWorks and blasting analyses were performed by using AUTODYN. A method was suggested to calculate theoretically the amount of muck which inflows into a tunnel based on the relationship between the tunnel and the fragmentation zone obtained from the analysis results. Also, muck hauling times were predicted based on the selection of construction equipment and the results were compared and analyzed. As a result, it was convinced that the amount of muck flowing into the tunnel could be effectively calculated by classifying the relationship between a tunnel and the fragmentation zone into 4 cases and using the mensuration by parts. Also it was confirmed that the closer blasting location is to the portal and the excavation surface of a tunnel, and the more blasting location deviates from the center line of the tunnel, the lesser amount of muck occurs and thus the muck hauling time decreases as well.
Effects of free surface using waterjet cutting for rock blasting excavation
Oh, Tae-Min ; Cho, Gye-Chun ; Ji, In-Taeg ;
Journal of Korean Tunnelling and Underground Space Association, volume 15, issue 1, 2013, Pages 49~57
DOI : 10.9711/KTAJ.2013.15.1.049
The conventional blasting method generates serious blasting vibration and underbreak/overbreak in spite of its high efficiency for rock excavation. To overcome these disadvantages, this paper introduces an alternative excavation method that combines the conventional blasting process with the free surface on the perimeter of the tunnel face using waterjet cutting technology. This proposed excavation method has advantages of (1) reducing vibration and noise level; (2) minimizing underbreak and overbreak; and (3) maximizing excavation efficiency. To verify the effects of the proposed excavation method, field tests were performed with a smooth blasting method at the same excavation conditions. Test results show that the vibration is reduced by up to 55% and little underbreak/overbreak is generated compared with the smooth blasting method. In addition, the excavation efficiency of the proposed method is greater than that of the smooth blasting method. The proposed blasting method with a free surface using waterjet cutting can be applied to urban excavation construction as well as to underground structure construction.
A fundamental study on the field applicability of the improved shape steel fiber shotcrete
Kim, Sang-Hwan ; Heo, Chung ;
Journal of Korean Tunnelling and Underground Space Association, volume 15, issue 1, 2013, Pages 59~68
DOI : 10.9711/KTAJ.2013.15.1.059
This paper presents the fundamental study on the field applicability of new-type steel fiber improved the existing shape. In this study, the theoretical reviews and the laboratory test programs were carried out to evaluate the mechanical characteristic of the new-type of steel fiber. The steel fiber sticking coefficient of new-type steel fiber was estimated from the test results. The laboratory scaled shotcrete rebound tests were also performed to analysis the field applicability of New-type steel fiber shotcrete and the mechanical behaviour of New-type steel fiber shotcrete were compared with that of the existing steel fiber shotcrete. It was found that the strength characteristic of New-type steel fiber shotcrete was increased.