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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Tunnel and Underground Space
Journal Basic Information
Journal DOI :
Korean Society for Rock Mechanics
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Volume & Issues
Volume 15, Issue 6 - Dec 2005
Volume 15, Issue 5 - Oct 2005
Volume 15, Issue 4 - Aug 2005
Volume 15, Issue 3 - Jun 2005
Volume 15, Issue 2 - Apr 2005
Volume 15, Issue 1 - Feb 2005
Selecting the target year
Evaluation of the Deformational Behavior of the Underground Research Tunnel in KAERI
Kwon Sangki ; Cho Won-Jin ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 87~101
Case Study on the Tunnel Collapse at the Shallow Depth
Baek Ki-Hyun ; Roh Jong-Ryun ; Kim Yong-Il ; Cho Sang-Kook ; Hwang Nag-Youn ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 102~110
○ ○ tunnel that is located at Iksan - Jangsu freeway ○ ○, has collapsed during construction at the valley with shallow depth. Although, the site investigations, such as TSP, drilling exploration and so of indicated the presence of discontinuities in this section. The RMR was upgraded and the construction were carried out because that not only actual rock qualities were relatively good during construction but also the tunnel foe was stabilized. However, the tunnel was collapsed at the same time blasting of full face, and surface and underground water was infiltrated due to the settlement of the upper part of the tunnel face. To restore the collapsed section, 3-d tunnel stability analysis was performed and suitable reinforcement methods were chosen. The cavity of the upper tunnel face was stabilized by means of UAM and ALC injection. And the settlement was restored using L.W grouting method.
Case Study about the Ground Characteristics Analysis of Tunnel Face Fault Fractured Zone
Min Kyoung-Nam ; Lim Kwang-Su ; Jang Chang-Sik ; Lim Dae-Hwan ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 111~118
The area of investigation belongs to Okchon metamorphic zone and the fault fractured zone runs parallel to the tunnel direction. It causes the independent decline of tunnel face and the slackness of the tunnel surrounding base so, after all, the severe displacement has occurred within the tunnel. Accordingly, the TSP(Tunnel Seismic Prediction) survey has been performed to investigate the extent of fault fractured zone and to analize its characteristics. Also, we have analized the behavior causes by performing the tunnel face mapping and drilling investigation, and confirmed the position and scale of geological anomaly area and front fractured zone which influences tunnel excavation and supporting. Collected data analyzed ground layer condition through 3 dimensional modeling. Several variables included in the modeling were analyzed by geostastistics. The analysis of the modeling data shows that the belt of weathering by fault fractured zone is developing on the basis of the right side of tunnel and that is decreasing to the left side. The fault fractured zone was confirmed that it has strike,
dip NW, and it is consisted of large-scale fractured zone including several anomalies. The severe displacement in tunnel is probably caused by asymmetrical load that n generated by the crossing of discontinuity and the rock strength imbalance of tunnel's both side by fault fractured zone, and judge that need tunnel reinforcement method of grouting etc.
The Mechanical Behavior of Jointed Rock Masses by Using PFC2D
Park Eui-Seob ; Ryu Chang-Ha ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 119~128
Although the evaluation of the mechanical properties and behavior of jointed rock masses is very important for the design of tunnel and underground openings, it has always been considered the most difficult problem. One of the difficulties in describing the rock mass behavior is the selection of the appropriate constitutive model. This limitation may be overcome with the progress in discrete element software such as PFC, which does not need the user to prescribe a constitutive model for rock mass. In this paper, a
m jointed rock mass of road tunnel site was analyzed. h discrete fracture network was developed from the joint geometry obtained from core logging and surface survey. Using the discontinuities geometry from the DFN model, PFC simulations were carried out, starting with the intact rock and systematically adding the joints and the stress-strain response was recorded for each case. With the stress-strain response curves, the mechanical properties of jointed rock masses were determined. As expected, the presence of joints had a pronounced effect on mechanical properties of the rock mass. More importantly, getting the mechanical response of the PFC model doesn't require a user specified constitutive model.
Optimal Estimation of Rock Mass Properties Using Genetic Algorithm
Hong Changwoo ; Jeon Seokwon ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 129~136
This paper describes the implementation of rock mass rating evaluation based on genetic algorithm(GA) and conditional simulation technique to estimate RMR in the area without sufficient borehole data RMR were estimated by GA and conditional simulation technique with reflecting distribution feature and spatial correlation. And RMR determined by GA were compared with the results from kriging. Through the analysis of the results from 30 simulations, the uncertainty of estimation could be quantified.
A Study on the Estimation of Diameter Distribution and Volumetric Frequency of Joint Discs Using the Least Square Method
Song Jae-Joon ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 137~144
An estimation technique of the joint diameter distribution using the least square method is suggested. When utilizing the technique by Song and Lee, the diameter distribution would be obtained only from the trace length distribution defined in an infinite window after the trace length distribution is estimated from the contained trace length distribution. With the new technique, however, the diameter distribution can be directly obtained from the sample histogram of the contained trace lengths. Compared with the previous technique, it shows a more accurate result for small sizes of joint samples and provides the joint geometry parameter of volumetric frequency. Verification of this new technique was completed by using Monte Carlo simulations.
A Study of Probabilistic Groundwater Flow Modeling Considering the Uncertainty of Hydraulic Conductivity
Ryu Dong-Woo ; Son Bong-Ki ; Song Won-Kyong ; Joo Kwang-Soo ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 145~156
MODFLOW, 3-D finite difference code, is widely used to model groundwater flow and has been used to assess the effect of excavations on the groundwater system due to construction of subways and mountain tunnels. The results of numerical analysis depend on boundary conditions, initial conditions, conceptual models and hydrogeological properties. Therefore, its accuracy can only be enhanced using more realistic and field oriented input parameters. In this study, SA(simulated annealing) was used to integrate hydraulic conductivities from a few of injection tests with geophysical reference images. The realizations of hydraulic conductivity random field are obtained and then groundwater flows in each geostatistically equivalent media are analyzed with a numerical simulation. This approach can give probabilistic results of groundwater flow modeling considering the uncertainty of hydrogeological medium. In other words, this approach makes it possible to quantify the propagation of uncertainty of hydraulic conductivities into groundwater flow.
Characteristics of the Horizontal Stress and the Possibility of Stress Induced Brittle Failure in Chuncheon-Yanggu Mountainous Region by the In-situ Stress Measurements
Bae Seongho ; Jeon Seokwon ;
Tunnel and Underground Space, volume 15, issue 2, 2005, Pages 157~167
Current initial rock stress state is one of the key factors required to evaluate the stability and failure around an excavated opening and its importance increases as the construction depth become deeper and the scale of the rock structure become larger. In this paper, the study was performed to evaluate the characteristics of the regional stress state at Chuncheon-Yanggu mountainous region, the East-North part of Kyeonggi Massif. Forty nine field stress measurements in 9 boreholes were conducted at the depth from 20 m to 290 m by hydraulic fracturing method. The fracturing tracing works were carried out by acoustic televiewer scanning. The study results revealed that the different intial rock stress states presented at different formation rock type and the excessive horizontal stress state with stress ratio(K) close to 3.0 was measured at the depth of 200 m and deeper in the intrusive unite body of the study area. The results from the investigation of excessive horizontal stress and its effect on failure mode showed that there exist several points where the localized excessive horizontal stresses are big enough to potentially induce brittle failures around the future openings greater than 100 m in depth within the granite body of the study area.