• The Journal of Engineering Geology
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• v.11 no.1
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• pp.51-62
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• 2001

Jurassic granites of three sites, Pocheon, Geochang and Habcheon, were analysed with respect to the characteristics of the rock cleavage. Microscopic analysis for the oriented thin sections of the specimens was conducted by using the scanline survey technique to measure microcrack direction, spacing and length. The results showed that the preferred orientations of microcrack developed in quartz and feldspar arc coincident with the orientation of quarry planes. The length of microcrack is related to grain size. The length of microcrack in coarse-grained granite is longer than that in relatively fine-grained granite. In all granites, microcracks related to the preferred orientations are well developed in order of rift, grain and hardway planes in number, length and density.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.167-178
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• 2002

Properties of discontinuity for Seoul Granite in northeastern part of Seoul City were analyzed by dividing structural domains into Surak and Bulam Mtn. areas. Important parameters measured among several engineering properties of a rock during tunnel excavation and road construction are as follows: 1) Orientation of joint, 2) joint spacing, 3) joint density, and 4) uniaxial compressive strength. Orientation, spacing, and density of joints can be directly measured during field investigation using scanline survey, circle-inventory method, and window survey. Uniaxial compressive strength of the rock was calculated by a simple correlation equation although it is originally necessary to prepare core samples in measuring it. Major orientations of joints measured from both areas are 3 sets of joints with different orientations. In other words, they are 2 sets of orthogonal joint and 1 set of sheet joint that is dipping at low angle, and have very similar orientations in both areas. Joint densities in both areas range from 0.039 and 0.066/cm, and average joint length are between 1.30 and 4.52m. Average joint spacing also has values from 10.3cm up to 59.6cm, and shows significant difference along specific orientation of scanlines measured. Values of uniaxial compressive strength calculated on the basis of Schmidt hammer rebound values range from 217 to 335 MPa, which indicates very strong rock type by classification of wall strength.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.20-32
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• 2008

The study shows a method called a square-inventory method, which is a better and faster method than scanline survey and window method for an analysis of slope stability. The study area is located in the Changri area, Boeun-Gun, Chungbuk, and consists of many formations of the Okcheon Supergroup. Various types of failure are observed from the phyllite including the rocks in the study area. The physical properties of meta-sedimentary rocks are that minerals of the rocks are composed of microcrystalline quartz and sericite, which are arranged parallel to bedding (or schistosity) and crenulation cleavage. Therefore, such properties affect geotechnical ones of the rock. The slope stability are analyzed by selecting 3 areas, each of which are divided into 2 or 3 slopes of $1m{\times}1m$ area that represent each of 3 investigation sites. The possibility of wedge and toppling failure is very high in all 3 areas by using square-inventory method. Although possibility of plane failure is weak in the investigation site 2, the plane failures are frequently found from the slope of site 2. The bedding (or schistosity) plane and cleavage, another types of discontinuity coexist in meta-sedimentary rocks uulike igneous rocks, and therefore are important factors to be considered together with joint structures in th ε analysis of slope stability.

• The Journal of Engineering Geology
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• v.9 no.1
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• pp.31-43
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• 1999

This study aims to quantify the distribution characteristics of the fracture system for the numerical modeling of groundwater flow in the north-eastern area of Yosu peninsula. The study area is composed mainly of volcanic rocks and granite. The regional and site scale lineament in the range of magnitude Order 1 to Order 3 were analyzed from the geologic map, air-photograph and shaded relief map. The geometric parameter of Order 4 fracture system was acquired from the scanline survey on the ground surface. There is a similar trend in the preferred orientation between the regional lineament and the Order 4 fracture system except the Set 4 of Order 4 fracture system which is not prominent in the type. That is classified to three fracture sat of high dip angle and one of ow dip angle. From the lineament trend. The orientation of Order 4 fracture system has similar characteristics in each rock termination mode analysis, it is considered that the fracture system was developed systematically and sequentially from Set 1 to Set 4 Filling materials are distinct relatively in low dip angle set. The fracture spacing follows to lognoral distribution and the fracture frequency corrected by the modified Terzaghi correction ranges from 0.38 to 1.01 per mater in each fracture set. The fracture trace lenght also follows to lognormal distribution and ranges from 2.9m to 3.7m in each fracture set.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.425-436
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• 2010

We established a stochastic 3-D fracture network system for fractured rock masses located in Il-Gwang Mine, Busan, to explore the relationship between the acidity of mine drainage and fracture geometry. A field scanline survey and borehole image processing were performed to estimate the best probability distributions of fracture geometry parameters. The stochastic 3-D fracture network system constructed for the rock masses was validated and deemed to be successful. The 3-D fracture network model was suitable for developing conceptual ideas on fluid flow in fractures at a field experimental site. An injection well and three observation wells were drilled at the field experimental site to monitor the acidity of mine drainage induced by the injection of fresh water. The field experiment, which was run for 29 days, yielded a significant relationship (with a high coefficient of determination) between the fracture geometry parameters and the acidity of mine drainage. The results show that pH increased with increasing relative frequency of fracture strike, and decreased with increasing fracture density. The concentration of $SO^{2-}_4$ decreased with increasing relative frequency of fracture strike, and increased with increasing fracture density.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.67-76
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• 2007

The characteristics of rockfall are determined by virtually all factors and conditions e.g. the physical figure of the slope such as inclination, height, roughness, the elemental figure of the slope such as vegetation and material deposited, and the shape and weight of the rockfall itself. Although it is one of the major factors to be considered in rockfall simulation, little attention has been given to the weight of the rockfall. And, since the size of the rockfall is dominated by joint spacing, the distribution of the rockfall block weight can be predicted as a function of the joint spacing. In this study, the weight distribution of rockfall was estimated by using the method of volumetric joint count, $J_{\nu}$, based on joint spacing, and $RQD-J_{\nu}$. The results indicate that the weight distributions were analogous in two methods, and the distribution was to be $75.3{\sim}76.7%$ for 200 kilograms or lesser, $15.0{\sim}16.6%$ for $200{\sim}400$ kilograms, and $6.7{\sim}9.7%$ for 400 kilograms or more, which show good matches with the actual on-site weight distribution. Therefore, the weight distribution of rockfall suggested in this paper is able to be considered as appropriate data for rockfall simulation.