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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
Editor in Chief :
Volume & Issues
Volume 16, Issue 6 - Dec 2006
Volume 16, Issue 5 - Oct 2006
Volume 16, Issue 4 - Aug 2006
Volume 16, Issue 3 - Jun 2006
Volume 16, Issue 2 - Apr 2006
Volume 16, Issue 1 - Feb 2006
Selecting the target year
New Observational Design and Construction Method for Rock Block Evaluation of Tunnels in Discontinuous Rock Masses
Hwang Jae-Yun ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 1~10
Rock masses in nature include various rock discontinuities such as faults, joints, bedding planes, fractures, cracks, schistosities, and cleavages. The behavior of rock structures, therefore, is mainly controlled by various rock discontinuities. In many tunnels, enormous cost and time are consumed to cope with the failing or sliding of rock blocks, which cannot be predicted because of the complexity of rock discontinuities. It is difficult to estimate the properties of rock masses before the rock excavation. The observational design and construction method of tunnels in rock masses is becoming important recently. In this paper, a new observational design and construction method for rock block evaluation of tunnels in discontinuous rock masses is proposed, and then applied to the tunnel based on actual rock discontinuity information observed in the field. It is possible to detect key blocks all along the tunnel exactly by using the numerical analysis program developed far the new observational design and construction method. This computer simulation method with user-friendly interfaces can calculate not only the stability of rock blocks but also the design of supplementary supports. The effectiveness of the proposed observational design and construction method has been verified by the confirmation of key block during the enlargement excavation.
Monitoring Result of Rock Mass Behavior during Excavation of Deep Cavern
Lee Hong-Gyu ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 11~25
The world's largest nucleon decay experiment facility is constructed at a depth of approximately 1,000 meters, in the Kamio Mine, Japan. The excavated cavern is consisted of a cylinder of 42.4 m high and a semi elliptical dome of 15.2 m high, with a bottom diameter of 40 m. The total excavation volume is approximately
. Because of the character as a large cavern excavation in deep underground, there is many unknown factors in rock mechanics. Based on the results of rock test and numerical analysis, the monitoring of rock mass behavior accompanying progress of construction was performed by various instruments installed in the rock mass surrounding the cavern. The monitoring data was used in the study of measures for cavern stability.
A Study on the Quantified Criteria in Determining the Geostructural Domain of Fractured Rock Mass
Um Jeong-Gi ; Cho Taechin ; Kwon Soon Jin ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 26~37
This study addresses the applicability of box fractal dimension,
, as an index of statistical homogeneity of fractured rock mass. The box-count method's capability in quantifying the combined effect of fracture density and size distribution is examined systematically. Total of 129 two-dimensional fracture configurations were generated based on different combinations of fracture size distribution and fracture density.
was calculated for the generated fracture network systems using the box-counting method. It was found that was standard deviation of trace length and fracture orientation have no effect on calculated
. The estimated
was found to increase with increasing total density and/or mean trace length. To explore the field applicability of this study, the statistical homogeneity of fractured rock mass was investigated at the rock slope and the underground facility using the box-counting method as well as conventional contingency table analysis. The results obtained in this study clearly show that the methodologies given in this paper have the capability of determining the statistical homogeneity of fractured rock mass.
Evaluation of Drainage System and Coupled Analysis of Heat Transfer and Water Flow for Ice Ring formation in Daejeon LNG Pilot Cavern
Jeong Woo-Cheol ; Lee Hee-Suk ; Lee Dae-Hyuck ; Kim Ho-Yeong ; Choi Young-Tae ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 38~49
LNG storage in lined rock cavern demands various techniques concerned with rock mechanics, thermo-mechanics and hydrogeology in design, construction and maintenance stage. LNG pilot cavern was constructed in Daejeon in order to verify these techniques. In this paper, evaluation of drainage system and ice ring formation was studied by numerical simulation. By Modflow analysis in the viewpoint of aquifer and Seep/W analysis in the viewpoint of flow system, it was verified that the drainage system in the pilot cavern was efficiently operated. Since ice ring formation can be simulated by interactive relation between heat transfer and water flow, coupled analysis of those was performed. In this analysis, the position of ice ring was presumed and it was demonstrated that the formation is affected by velocity and direction of groundwater flow.
Evaluation of Rock Damage Zone Using Seismic Logging Method
Kang Seong-Seung ; Hirata Atsuo ; Obara Yuzo ; Haraguchi Naoyuki ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 50~57
Development of structures such as slope and tunnel, waste disposal, oil and LPG storages, and underground power house and so on, is increasing with the year. The method for appropriate estimation of rock state such as fresh or damaged rocks is also requested with increasing structural development. On these purposes, seismic logging system, which is a simple and easy way for handling as well as small and light, has been developed. Seismic logging method is one of logging tests, which is able to evaluate the state of rock mass with various shapes and is possible to obtain the relatively accuracy data at situ state. In addition, seismic logging method is at to apply to estimate structural behavior, before and after support installed. According to the results obtained from this study, firstly, it is clear that the extent of damage in rock slope due to blasting is able to be evaluated with quantity using seismic logging method, moreover to decide the damage zone in rock slope reasonably. Secondly, it is expected that installing depth of support is able to be decided more effectively and economically, using the results of seismic logging data. Finally, seismic logging method is also able to be applied safety supervision of structures, before and after support installed.
Dynamic Frictional Behavior of Saw-cut Rock Joints Through Shaking Table Test
Park Byung-Ki ; Jeon Seokwon ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 58~72
In recent years, not only the occurrences but the magnitude of earthquakes in Korea are on an increasing trend and other sources of dynamic events including large-scale construction, operation of hi띤-speed railway and explosives blasting have been increasing. Besides, the probability of exposure fir rock joints to free faces gets higher as the scale of rock mass structures becomes larger. For that reason, the frictional behavior of rock joints under dynamic conditions needs to be investigated. In this study, a shaking table test system was set up and a series of dynamic test was carried out to examine the dynamic frictional behavior of rock joints. In addition, a computer program was developed, which calculated the acceleration and deformation of the sliding block theoretically based on Newmark sliding block procedure. The static friction angle was back-calculated by measuring yield acceleration at the onset of slide. The dynamic friction angle was estimated by closely approximating the experimental results to the program-simulated responses. As a result of dynamic testing, the static friction angle at the onset of slide as well as the dynamic friction angle during sliding were estimated to be significantly lower than tilt angle. The difference between the tilt angle and the static friction angle was
and the difference between the tilt angle and the dynamic friction angle was
. The decreasing trend was influenced by the magnitude of the base acceleration and inclination angle. A DEM program was used to simulate the shaking table test and the result well simulated the experimental behavior. Friction angles obtained by shaking table test were significantly lower than basic friction angle by direct shear test.
Analysis of Effect of Railway Tunnel Excavation on Water Levels of a National Groundwater Monitoring Station in Mokpo, Korea
Lee Jin-Yong ; Yi Myeong-Jae ; Choi Mi-Jung ; Hwang Hyoun-Tae ; Moon Sang-Ho ; Won Jong-Ho ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 73~84
Effects of railway tunnel excavation on water level at a national groundwater monitoring station in Mokpo were evaluated by field investigation and numerical groundwater modeling. The water level at the station has experienced a decline of about 5 m within 1 year since July 2002. From the field investigation, it was concluded that decrease of precipitation oo increase of grundwater use was not reason for the decline. The Mokpo tunnel of new Honam railway, 70 m apart from the national station, appeared most plausible cause and a period of the tunnel excavation generally well matches up that of the drawdown. To quantify the effects of the tunneling on the water level, a groundwater flow modeling was performed. Especially, a most probable conceptual model was optimized through multiple preliminary simulations of various scenarios because there were few hydrogeological data available for the study area. The optimized model was finally used for the quantification. Based on the field investigation and the numerical simulations, it was concluded that the tunnel excavation was one of the most probable reasons for the substantial water level decline but further hydrogeologic investigation and continuous monitoring are essentially required for the surrounding area.
Experimental Study on the Determination of Critical Velocity for the Case of Fire in Long Traffic Tunnels
Yoon Chanhoon ; Yoon Sungwook ; Yoo Yongho ; Kim Jin ;
Tunnel and Underground Space, volume 16, issue 1, 2006, Pages 85~94
In this study, scaled model tests were carried out to decide the optimal critical velocity, to prevent back layering in the case of fire in a long traffic tunnel. Realistic estimates were made for the time required for people to escape ken the tunnel and far the time required by the ventilation operator to increase the system speed to full capacity. The analysis, predicts that the emergency ventilation will start about 240 seconds after the tunnel fire. It was also found that prevention of back layering would occur within 4 minutes after fan operation. To find out optimal critical velocity, a 1/50 scaled model tunnel(diameter : 0.2 m and length : 20 m) based on the Froude similarity technique was constructed. Changing
values in the Tetzner's equation, smoke propagation was observed. From the experiment, it was concluded that using a
value of 0.5 to prevent back layering successfully allowed time for safe evacuation.