• Tunnel and Underground Space
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• v.11 no.3
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• pp.270-278
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• 2001

Two numerical methods such as DEM and FDM were adopted to analysis of rock slope stability, of which dimensions are about 150 m(length), 58 m(height), 70°dip, in Halla limestone mine. For this rock slope stability analysis, strength reduction method was used to calculate the safety factor of slope through numerical method. To keep the rock slope safely, it is proposed to reduce the height of the rock slope from 58 m to 45 m and to reduce the angle of the slope from 70°to 55°, too.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2011.09a
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• pp.89-97
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• 2011

Brittle failure of rock is a classical rock mechanics problem. Rock failure not only involves initiation and propagation of single crack, but also is a complex problem associated with initiation, propagation and coalescence of many cracks. As the most important feature of rock material properties is the heterogeneity, the Weibull statistical distribution is employed in the rock failure process analysis (RFPA) method to describe the heterogeneity in rock properties. In this paper, the applications of the RFPA method in geotechnical engineering and rockburst modeling are introduced with emphasis, which can provide some references for relevant researches.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.11b
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• pp.103-114
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• 2002

Stability of cut-slope is considered to have a deep relationship with rock types since rock has its own engineering and geological characteristic such as shear strength, durability, weathering profile, geological structures. Therefore, analysis of geological and engineering characterisics of rock mass is essential for the evaluation of rock slope stability This paper introduces the statistical data of slope failure cases which was collected from highway slopes constructed in sedimentary rock mainly of shale in Ky ng-sang Basin. Primary failure feature in this area is planar failure along the bedding regardless of slope geometry. Even a disasterous slope failure case due to the thick clay layer between the beddings was reported. Failures and rock fall were reported to ocurred frequently after the completion of cutting due to the weathering, so long-term slope stability should be considered as a important factors in design.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.339-346
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• 1999

The stability of rock slope is considered to have a deep relation with types of rocks because types of rocks have their own typical weathering profiles, geological structures and characteristics of failures. Therefore it is essential for the evaluation of rock slope stability to analyze geological and engineering characteristics in rock mass. The data which collected from investigated slopes in sedimentary rock of Kyengsang Basin along highways were analyzed. Primary factors affecting slope stability in rock mass are: dips and strikes of slopes and discontinuities, shear strength of discontinuities, slope geometry and geological structures etc.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.614-621
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• 2004

Blasting is a technique for rock excavation: For instance, a rock cutting in a mountain side to prepare a base for a road. The blasting damage affect the rock slope stability. Therefore control blasting must be used. In this study, cutting cases of Sixty-nine rock blasts were investigated. Blasting damage patterns in rock slope and reinforcement methods are studied.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.03a
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• pp.89-96
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• 1997

• Tunnel and Underground Space
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• v.7 no.2
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• pp.150-157
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• 1997

Various analytical, empirical and theoretical methods for slope stability assessment were applied on slopes to develop aggregate quarry optimally. Among them are block theory, stereographic analysis, RMR, SMR, limit equilibrium method and maximum likelihood. Test site was estimated that slopes were apt to fail although rock quality was good. Modified direction and dip angle was suggested for stability. To reduce the overbreak and to improve the stability, the vertical blasting was recommended for new subground level.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.275-286
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• 2007

In construction of a structure in underground space, in-situ stress in rock mass has great effect on the stability of the structure. Especially, the direction and magnitude of rock stress have influence on the excavation method, the choice of support and reinforcement method for establishing the stability of tunnel. Therefore, it is very important to consider the characteristics of in-situ stress in rock mass for tunnel stability analysis. In this study, a reasonable design method for underground structure was reviewed through the case study for tunnel design considering in-situ rock stress. For this purpose, the estimation for SRF (Stress Reduction Factor) as input parameter in rock classification using Q-System and the assesment for tunnel support were studied. Also, considering the characteristics of in-situ rock stress such as the magnitude of K and the direction of principal stress, the parameter studies for tunnel stability analysis were carried out. An improved method was proposed for obtaining the better results in the tunnel stability analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.387-401
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• 2007

Recently, because of the restriction of land for construction and interference of adjacent structure, parallel tunnels with small clearance have been planned and constructed in many sites. In this case, the stability of pillar at center part is very important factor to satisfy the stability of tunnel structure under the construction. In this paper, numerical analyses for the asymmetry parallel tunnels with a narrow width of pillar have been carried out to search for the optimum reinforcement measure for rock pillar and verify the stability of tunnel. Rock pillar between each single tunnel is supposed to be under heavy load by rock mass. The analysis of stress state at rock pillar at various cases for construction conditions is required to investigate the structural behaviour of tunnels and stability of the pillar. Strength-stress ratio is calculated based on the failure theory of rock and the safety factor of tunnel is computed with strength reduction technique. Through these numerical results, reasonable reinforcement measures for rock pillar at parallel tunnel were established and recommended.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.167-178
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• 2003

Damage and overbreak of the remaining rock induced by blasting can not be avoided during tunnel construction which may result in either short-term or long-term tunnel instability. Therefore, in this paper, a methodology to take into account the effect of blast-induced damage in tunnel stability assessment is proposed. Dynamic numerical analysis was executed to evaluate damage and overbreak of the remaining rock for the most common blasting pattern in road tunnel. Rock damage was quantified by utilizing the damage variable factor which is adopted proposed in continuum damage mechanics. The damaged rock stiffness and the damaged failure criteria are used to consider the effect of rock damage in tunnel stability analysis. The damaged geological strength index of the damaged rock was newly proposed from the relationship between deformation modulus and geological strength index. Also the Hoek-Brown failure criteria of the damaged rock was obtained using the damaged geological strength index. Analysing the tunnel stability with the consideration of the blast-induced damage of remaining rock, it was found that the extend of plastic zone and deformation increased compared to the undamaged rock. Therefore the short-term or long-term tunnel stability will be threatened when the rock damage from blasting is ignored in the tunnel stability analysis.