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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Tunnel and Underground Space
Journal Basic Information
Journal DOI :
Korean Society for Rock Mechanics
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Volume & Issues
Volume 21, Issue 6 - Dec 2011
Volume 21, Issue 5 - Oct 2011
Volume 21, Issue 4 - Aug 2011
Volume 21, Issue 3 - Jun 2011
Volume 21, Issue 2 - Apr 2011
Volume 21, Issue 1 - Feb 2011
Selecting the target year
Study on a 3-Dimensional Rock Failure Criterion Approximating to Mohr-Coulomb Surface
Lee, Youn-Kyou ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 93~102
In spite of being unable to take into the effect of intermediate principal stress, Mohr-Coulomb and Hoek-Brown criteria are very popular as rock failure criteria. The recent researches reveal that the influence of intermediate principal stress on the failure strength of rock is substantial, so that 3-D failure criteria in which the intermediate principal stress could be considered is necessary for the safe design of the important rock structures. In this study, the likely application of the 3-D failure criterion proposed by Jiang & Pietruszczak (1988) to the prediction of the true triaxial strength of rock materials is discussed. The failure condition is linear in the meridian plane of principal stress space and it is represented by the smooth surface contacting the corners of the Mohr-Coulomb surface. The performance of the Jiang & Pietruszczak's criterion is demonstrated by simulating the actual true triaxial tests on the rock samples of three different rock types.
A Demolition Experiment of a Scaled Model for a Concrete Box Girder Bridge
Yang, Hyung-Sik ; Jang, Hyong-Doo ; Ko, Young-Hun ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 103~108
Along with series of concrete block experiments, a demolition experiment was conducted for a scaled concrete box girder bridge to investigate collapse and blast behavior. Tri nitro toluene (TNT), the standard explosive for strength was adopted as concussion charge. The result show that demolition was caused by not only direct detonation pressures at charging spots but also blast pressures at inner wall of concrete box girder.
Estimation of Dynamic Brazilian Tensile Strengths of Rocks Using Split Hopkinson Pressure Bar (SHPB) System
Yang, Jung-Hun ; Ahn, Jung-Lyang ; Kim, Seung-Kon ; Song, Young-Su ; Sung, Nak-Hoon ; Lee, Youn-Kyou ; Cho, Sang-Ho ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 109~116
In this study, we estimated the dynamic tensile strength and strain rate from Brazilian tensile test using Split Hopkinson Pressure Bar (SHPB) system. A pulse shaping technique, which controls the shape of the impactinduce incident waves, was used for achieving the dynamic stress equilibrium and constant strain rate before fracture of rock samples. Three kinds of rock type, Inada granite, Kimachi sandstone and Tage tuff were prepared as 50mm in diameter and 26 mm in thickness. The high-speed videography system was used to observe the fracture processes of the rock samples. As the results of the tests, the ratio of dynamic tensile strength and static tensile strength was 11.9 for Inada granite, 8.5 for Kimachi sandstone and 9.2 for Tage tuff.
The DFN-DEM Approach Applied to Investigate the Effects of Stress on Mechanical and Hydraulic Rock Mass Properties at Forsmark, Sweden
Min, K.B. ; Stephansson, O. ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 117~127
The purpose of this study is to demonstrate the effect of in-situ rock stresses on the deformability and permeability of fractured rocks. Geological data were taken from the site investigation at Forsmark, Sweden, conducted by Swedish Nuclear Fuel and Waste Man-agement Company (SKB). A set of numerical experiments was conducted to determine the equivalent mechanical properties (essentially, elastic moduli and Poisson's ratio) and permeability, using a Discrete Fracture Network-Discrete Element Method (DFN-DEM) approach. The results show that both mechanical properties and permeability are highly dependent on stress because of the hyperbolic nature of the stiffness of fractures, different closure behavior of fractures, and change of fluid pathways caused by deformation. This study shows that proper characterization and consideration of in-situ stress are important not only for boundary conditions of a selected site but also for the understanding of the mechanical and hydraulic behavior of fractured rocks.
Numerical Approach for Determination of Shut-in Pressure in Hydrofracturing Test
Choi, Sung-O. ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 128~137
The shut-in pressure calculated in common hydrofracturing test for vertical borehole equals generally to the minimum horizontal principal stress, so it should be considered as an essential parameter for determining the in-situ stress regime around the rock mass. It shows usually an ambiguous value in pressure-time history curves, however, because of the relationship between the behavior of hydraulic fractures and the condition of remote stress regime. In this study, a series of numerical analyses have been carried out to compare several methods for determining the shut-in pressure during hydrofracturing. The hydraulic-mechanical coupling has been applied to numerical analysis for simulating the fracture propagation by hydraulic pressure, and the different discontinuity geometry has been considered in numerical models to examine the effect of numerical element shape on fracture propagation pattern. From the numerical simulations with the four different discontinuity geometries, it was revealed that the shut-in pressure obtained from graphical methods rather than statistical method was relatively small. Consequently a care should be taken in selecting a method for determining the shut-in pressure when a stress anomaly around borehole and a fracture propagation with complicate mechanism are considered.
Effect of Degradation of Rock Mass Properties Caused by Water Pressure on the Stability of Mine Gallery
Yoon, Yong-Kyun ; Baek, Young-Jun ; Jo, Young-Do ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 138~144
Mine closure does often accompany the flooding of mine galleries due to ceasing a pumping operation. When a mine gallery is flooded, rocks around the gallery are fully saturated and the gallery is subject to a water pressure. The uniaxial unconfined compressive strength of a rock depends on its water content and decreases as the water content increases. A water pressure may originate the crack growth of a rock or the discontinuity growth of rock mass. Although the water in a gallery will give some support pressure inside the gallery, the degradation of rock mass properties caused by a water pressure will reduce the stability of the gallery. In this study, 2-dimensional discontinuous and 3-dimensional continuous numerical analyses have been conducted to evaluate an effect that a reduction of rock mass properties around the gallery induced by a water pressure has on the stability of mine gallery. The numerical analyses show that a reduction of rock mass properties caused by a water pressure increases displacements of rock mass around mine gallery. 2-dimensional model is found to give larger values of displacement than 3-dimensional model.
Estimation of Weathering Characteristics of Sandstone and Andesite by Freeze-Thaw Test
Kang, Seong-Seong ; Kim, Jong-In ; Obara, Yuzo ; Hirata, Atsuo ;
Tunnel and Underground Space, volume 21, issue 2, 2011, Pages 145~150
Variations of physical properties such as weight loss rate, wave velocity and uniaxial compressive strength after performing freeze-thaw cyclic test were measured in order to define weathering characteristics of sandstone and andesite. Weight change in specimens of the two rocks decreased with increasing the repetition number of freeze-thaw cyclic test. In particular, weight loss of andesite specimens was very irregular. P-wave velocity of sandstone specimens decreased more than 5%. On the other hand, P-wave velocity of andesite specimens do not vary up to 500 cycles and decreased more than 5% after 1000 cycles. This implies that the sandstone are easily weakened and loosened by weathering processes, while the andesite are relatively strong. In addition, the wave velocity changes of the andesite specimens coincident with the weight change. Uniaxial compressive strengths of the sandstone specimens slightly decreased at the early stage of the freezing-thawing cyclic test, then tended to be irregular after 64 cycles. In conclusion, the rock specimens showed smaller weight loss, less had lower strength reduction rate.