• Geotechnical Engineering
• /
• v.25 no.9
• /
• pp.20-29
• /
• 2009

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.18 no.1
• /
• pp.109-117
• /
• 2016

This paper is focused on the determination of friction parameter which is a predominant factor in the design of inflatable structure system. This inflatable structure system is very valuably used to protect passively and rapidly the possibilities of tunnel damages by flooding threats and unusual leakage to be occurred during and after underground infrastructure construction. In particular, this system should be necessary in subsea tunnel. This study presents the experimental results obtained from the relative friction characteristics tests of the fabric materials that constitute the inflatable structure. In order to evaluate the relative friction behaviour of the inflatable structure system, friction tests and scaled model tunnel friction tests are carried out. The friction tests are carried out to determine the friction coefficient for different surface conditions between tunnel and inflatable structure. These friction coefficients are then evaluated and compared with the result obtained from the model tunnel friction tests. Interaction behaviours between tunnel and system are also reviewed and described in this study. The results clearly show that the friction coefficients derived from scaled model slippage tests are about 12% lower than values obtained from the friction tests. In addition, this study will be necessary to verify the real friction behaviour with prototype tests before applying in practice.

• The Journal of Engineering Geology
• /
• v.19 no.3
• /
• pp.261-268
• /
• 2009

Tunnel measurements provide crucial information on the ground stability during the excavation, visualizing the ground behavioral characteristics with quantitative dada. Generally, the frequency of the measurements is greater during the early stage of the tunnelling process and reduced with time. However, there are no quantitative criteria established for either the activities, such as the time, location and frequency of the measurement or the management guidance, especially for the site of subtle and unexpected displacement during the excavation. It is, however, still challenging to assess behavioral characteristics of subtle and unexpected displacement after stabilization. In this study, we propose a new method to assess stability and to analysis the behavioral characteristics of subtle and unexpected displacement after stabilization using statistic control charts of displacements. We also present a test result on the applicability of control chart and CUSUM control chart to measured displacements.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2000.09a
• /
• pp.147-154
• /
• 2000

The influence of the mined-out caves on the stability of the high speed railway tunnel was investigated with a series of geological logging and in-situ tests on the one hand, and with the rock mass classification using the multiple regression analysis on the other hand. The rock mass in this area can be classified as 'fair', and the condition of the discontinuities plays the most important role in the classification of the rock mass. The results of the analysis obtained by the FLAC showed that the western part of the tunnel locating at 50m above the mine cavities could be affected by subsidence associated with a considerable deformation, the magnitude of which might depend on the properties of the rock mass. Key word : multi regression analysis, subsidence, mine cavities

• Journal of the Korean GEO-environmental Society
• /
• v.8 no.6
• /
• pp.29-36
• /
• 2007

The control and prediction of surface settlement, gradient and ground displacement are the main factors in urban tunnel construction. This paper carried out the estimation and prediction of ground behavior around tunnel due to excavation using computational method and case study in detail for the analysis of deformation behavior in urban NATM tunnel. Computational method was performed by FLAC-2D with strain softening model and elastic plastic model. Field measurements of surface subsidence and ground displacement were adopted to monitor the ground behavior resulting from the tunneling and these values were applied to modify tunnel design parameters on construction.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.10 no.4
• /
• pp.421-430
• /
• 2008

In discontinuous rock masses, hydraulic-mechanical coupled analyses are required since groundwater flow in joints have a great influence on the stability of a subsea tunnel. In this study, a sensitivity analysis was performed based on coupled analysis to verify the routine which can estimate the safety factor of a tunnel in discontinuous rock mass. To this end, 324 cases of numerical calculations were performed with a commercial program, UDEC-2D. As a result, it was confirmed that the proposed routine for coupled analysis in discontinuous rock mass could give a reasonable result for the estimation of safety factor of a tunnel. Therefore, it is expected that the safety factor estimation method used in this study can be effectively applied for the stability estimation of a subsea tunnel in discontinuous rock masses.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.5
• /
• pp.339-357
• /
• 2021

As the construction of trans infrastructure using the underground tunnel have been rapidly increased, various nearby excavation of existed underground facility including subway structure has been occurred in urban tunnelling. The concern and worry relating to the safety and stability of the existed facility by nearby excavation is becoming the key issues in urban tunnelling. In this study, it was conducted for existed the subway station structure at Seoul subway line which was closely located in the new Dongbuk urban metro railway to determine the behavior characteristics of station structure according to adjacent tunnel construction. Also, it was reviewed the evaluation of the safety zone and excavation method for subway structure. And after a review of damage evaluation, track irregularities and structural calculation by using a numerical analysis, stability of the subway structure according to nearby tunnel excavation was evaluated to be secured. This study is expected to be applied as useful reference in advance if you need to review the effects of existed structure according to nearby construction in complex urban tunnelling.

• Tunnel and Underground Space
• /
• v.12 no.3
• /
• pp.179-188
• /
• 2002

This study is to understand the effect of the vibration and the stress changes due to the excavation of 2 arch parts of a tunnel, which is a Gyungbu Express Railway tunnel, on the tunnel itself and adjacent slopes in advance, and to analyze the stability. For the estimation of ground conditions, borehole tests, borehole camera logging and seismic logging were performed. Ground properties at a specific location were determined as input constants by performing 2 dimensional analyses with possible ranges of uncertain ground properties. Static and pseudo-static (due to blasting vibration) factors of safety were calculated. The behavior of the tunnel and its vicinity due to the tunnel excavation were predicted by 3 dimensional analyses. It was also tested whether the support system was proper.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.1
• /
• pp.1-9
• /
• 2017

In this study, a test-bed system simulated a tunnel and concrete track is tested on cite and invested an allowed limit of multi-layered sound absorbing panel for reducing noise reflected on the concrete track in train tunnel considering the criteria and limitation on the theoretical back ground. The studied results are an effective evaluating system of the sound absorbing coefficient influenced fluid effects depending on the vehicle speed in the urban train tunnel and measuring not only structural behaviors of maximum displacement and acceleration of the panel but also dynamic characteristics of damping ratio and natural frequency.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.6
• /
• pp.403-421
• /
• 2021

Most of the urban tunnels in Korea, which are represented by the 1st to 3rd subways, use the drainage tunnel by NATM. Recently, when a construction project that actively utilizes large-scale urban space is promoted, negative effects that do not conform to the existing empirical rules of urban tunnels may occur. In particular, there is a high possibility that groundwater fluctuations and hydrodynamic behavior will occur owing to the practice of tunnel technology in Korea, which has mainly applied the drainage tunnel. In order to solve the problem of the drainage tunnel, attempts are being made to control groundwater fluctuations. For this, the establishment of tunnel groundwater management standard concept and the analysis of the tunnel hydraulic behavior were performed. To prevent the problem of groundwater fluctuations caused by the construction of large-scale tunnels in urban areas, it was suggested that the conceptual transformation of the empirical technical practice, which is applied only in the underground safety impact assessment stage, to the direction of controlling the inflow in the tunnel, is required. And the relationship between the groundwater level and the inflow of the tunnel required for setting the allowable inflow when planning the tunnel was derived. The introduction of a tunnel groundwater management concept is expected to help solve problems such as groundwater fluctuations, ground settlement, depletion of groundwater resources, and decline of maintenance performance in various urban deep tunnel construction projects to be promoted in the future.