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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 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
Numerical Analysis on Cutting Power of Disc Cutter with Joint Distribution Patterns
Lee, Seung-Joong ; Choi, Sung-O. ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 151~163
The LCM test is one of the most powerful and reliable methods for designing the disc cutter and for predicting the TBM (Tunnel Boring Machine) performance. It has an advantage to predict the actual load on disc cutter from the laboratory test on the real-size large rock samples, however, it also has a disadvantage to transport and/or prepare the large rock samples and to need an extra cost for experiment. Moreover it is not easy to execute the test for jointed rock mass, and sometimes the design model estimated from the test can not be applied to the real design of disc cutter. In order to break this critical point, lots of numerical studies have been performed. PFC2D can simulate crack propagation and rock fragmentation effectively, because it is useful in particle flow analysis. Consequently, in this study, the PFC2D has been adopted for numerical analysis on cutting power of disc cutter according to the different angle of joint, the different direction of joint, and the different space of joint with jointed rock mass models. From the numerical analyses, it was concluded that the bigger cutting power of disc cutter was needed for reverse cutting direction to joint rather than for forward direction, and the cutting power of disc cutter was increased with decreasing the dip angle of joint and decreasing the space of joints in reverse cutting direction. The more precise numerical model for disc cutter can be developed from comparison between the numerical results and LCM test results, and the resonable guideline is expected for prediction of TBM performance and disc cutter.
Numerical Study on the Optimal Shape of Concrete Plug for Compressed Air Energy Storage Caverns
Park, Doh-Hun ; Kim, Hyung-Mok ; Ryu, Dong-Woo ; Synn, Joong-Ho ; Song, Won-Kyong ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 164~173
In the present study, the stability of a compressed air energy storage cavern was numerically assessed by concrete plug shapes in order to investigate the optimal shape of concrete plug. The concrete plugs were cylindrical, embedded cylindrical, tapered, and wedged in shape. The stability assessment was carried out based on factor of safety through a strength reduction method and a volume ratio which refers to the ratio of the volume of yield regions in concrete induced by internal pressure to all concrete volume. The results from the present study indicated that the embedded cylindrical and taper shaped plugs were mechanically more stable than the cylindrical and wedge shaped plugs. However, from a comparison of stress distributions in rock mass between the embedded cylindrical and taper shaped plugs, the taper shaped plug was found to be more optimal than the embedded cylindrical plug, since the embedded cylindrical plug caused more stress concentration in the interface between the plug and rock mass than the taper shaped plug.
Anisotropic Version of Mohr-Coulomb Failure Criterion for Transversely Isotropic Rock
Lee, Youn-Kyou ; Choi, Byung-Hee ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 174~180
An anisotropic version of Mohr-Coulomb failure criterion is proposed in order to provide a strength criterion for transversely isotropic rock. The concept of fabric tensor introduced by Pietruszczak & Mroz (2001) is employed to define the friction angle and cohesion as scalar functions of the fabric tensors. The anisotroy in these two strength parameters are calculated in association with the consideration of the relative rotation between the principal stress coordinate and the principal material triad. The critical plane on which the anisotropic function maximized is found by an optimization technique based on the Lagrange multiplier method. To demonstrate the performance of the anisotropic failure criterion, conventional triaxial tests on the samples having various inclinations of weakness plane are simulated and the resulting triaxial strength and dip angle of failure plane are discussed.
Development of an In Situ Direct Shear Test Apparatus and Its Field Application
Kim, Yong-Phil ; Lee, Young-Kyun ; Lee, Sung-Kook ; Um, Jeong-Gi ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 181~191
It is very difficult to prepare a lab. test specimen from weak rock masses affected by faults, highly fractured zone or weathered zone. In conventional method of in situ direct shear test a rock block is sheared inside galleries, where reactions for the hydraulic jacks are available. A new in situ direct shear test apparatus has been developed in this study to perform the test inside galleries as well as open pit conditions. The apparatus is composed of normal and shear reaction plates including load transfer plates, hydraulic cylinder systems, load cells, multistage shear boxes with fixing devices, and needle rollers. Maximum size of the test block is
mm, and procedures of the test block preparation has been suggested. To explore the field applicability of in situ direct shear test apparatus, proper test block site was investigated by extensive geological field survey. In situ direct shear test has been successful in producing most of information related to strength and deformability of the weak rock.
A Study on the Estimation of Load Distribution Factors Considering Excavation Methods and Initial Stress Conditions
Park, Yeon-Jun ; Ryu, Il-Hyung ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 192~204
In this study, 3-D analyses were conducted while taking every construction stage into account. Then 2-D analyses were conducted which yield the same results with the 3-D results. The crown settlement normalized by the ultimate value was compared during the process to overcome the discrepancy caused by different dimensions. When a bench or a core is left uncut to give extra support to the face and eventually the whole excavation boundary, this extra supporting effect also has to be included in the analysis. In this study, this effect is also implemented in terms of the load distribution factor. When the length of the bench is very short compared to the diameter of the tunnel in such cases as in short bench cut or in mini-bench cut, the supporting effect of the face does not disappear even after the bench is completely excavated and supported since the face is still too close to the point of interest. The 4th load distribution factor was defined to stand for the advance of the face after the completion of the excavation cycle. The 4th load distribution factor turned out to be very useful in determining the load distribution factors when a tunnel is excavated by bench cut with various bench lengths under different initial conditions.
Study on the Geotechnical Characteristics of Granite in Korea and their Correlation with Rock Classification Method
SunWoo, Choon ; Ryu, Dong-Woo ; Kim, Hyung-Mok ; Kim, Ki-Seog ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 205~215
In this study, we analyzed physical properties of granites and their correlation with rock mass classification methods. The granite samples were obtained from field survey, in-situ borehole tests and laboratory tests for a design phase of various roads, railways and other civil engineering works in Korea. Among the measured physical properties, the results of unit weight, compressive strength, tensile strength, seismic velocity, cohesion, friction angle, elastic modulus and deformation modulus were introduced. We also correlated these properties with the compressive strength. The results of different rock classification method of RQD, RMR, and Q-system against the granites in Korea were compared with each other, and the correlation equations were proposed in a more simplified form. We also derived RMR values using the compressive strength as well as the RQD values of in-situ drilled cores, and estimated the deformation modulus of in-situ rock mass in terms of the RMR values.
Numerical Simulation of Radial Strain Controlled Uniaxial and Triaxial Compression Test of Rock Using Bonded Particle Model
Lee, Chang-Soo ; Kwon, Sang-Ki ; Jeon, Seok-Won ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 216~224
In this study, Class II behavior of rock failure process under uniaxial and biaxial compression has been numerically simulated using bonded particle model. Class II behavior of rock was simulated by radial strain controlled uniaxial and biaxial compression tests using a suggested method of ISRM. Micro-parameters used in the simulation were determined based on the laboratory uniaxial compression tests carried out at
Hard Rock Laboratory, Sweden. Class II behavior of
rock was effectively simulated using newly proposed numerical technique in this study, and the results of numerical simulations show good similarity with the complete stress-strain curves for Class II behavior obtained from the laboratory tests.
Borehole Heater Test at KAERI Underground Research Tunnel
Kwon, S. ; Lee, C. ; Yoon, C.H. ; Jeon, S.W. ; Cho, W.J. ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 225~234
In this study, an in situ heater test for investigating the thermo-mechanical behavior related to heat flow was carried out. It was the first in situ heater test in Korea. For the test, an adequate design of heater, observation sensors, and data logging system was developed and installed with a consideration of the site condition and the test purposes. It was possible to observe that steep joints are overwhelmingly developed in the test area from a joint survey. The major rock and rock mass properties at the test site could be determined from the thermal and mechanical laboratory tests using the rock cores from the site. From the measured rock temperature distribution, it was possible to observe the influence of the rock joints and the heat flow through tunnel wall. When the heater temperature was maintained as
, the rock temperature at 0.3 m from the heater hole was increased up to
Numerical Study on the Effectiveness of Guide Holes on the Fracture Plane Control in Smooth Blasting
Kim, Hyon-Soo ; Kim, Seung-Kon ; Song, Young-Su ; Kim, Kwang-Yeom ; Cho, Sang-Ho ;
Tunnel and Underground Space, volume 21, issue 3, 2011, Pages 235~243
In this study, a control blast method, which utilizes crack guide holes, is suggested to achieve smooth fracture plane and minimize blast damage zone (BDZ) in smooth blasting. In order to verify the effectiveness of crack guide holes on the fracture plane control in blasting, fracture process analyses which consider regular smooth blasting and guide hole smooth blasting had been conducted and the fracture planes resulting from the analyses had been compared. The analyses models considered the ignition of the blast holes using detonation cords and each guide hole placed between blast holes. From the results, the smooth blasting utilizing guide holes showed lower fracture plane roughness than regular smooth blasting method in the hole spacing range between 20 to 40cm.