• The Journal of Engineering Geology
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• v.13 no.2
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• pp.193-205
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• 2003

Fine grained granite, porphyritic granite and biotite granite together with intruded and extruded andesitic rocks are distributed in the study area which is bounded by the Yangsan and Dongrae faults. A new domestic road is being constructed along the area between the two major faults. The NNE trending Bupki fault and NE trending Myungkog fault are also developed within the area cross the road. The sheeting joints with dips of less than 30 degrees are only developed in the area of granite outcrop. High angle joints can be divided into 3 sets, such as, NE trending, NW trending and nearly EW trending joints. The joint space is mostly more than 20cm and the joint compressive strength is more than 100 MPa. These data show that even though the study area is situated between large faults, the ground condition is good because the damage zone of the Yangsan and Dongrae faults is relatively narrow.

• The Journal of Engineering Geology
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• v.13 no.1
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• pp.107-127
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• 2003

After detailed geological mapping, structural and fracture-density data were collected and analyzed in the vicinity of Cheonseong and Jeongjok Mts., Gyeongsangnam-do. A extensive dextral strike-slip fault (Beopgi Fault) Parallel to Yangsan and Dongrae Faults, a dextral-transtensional-NW fault, and a few intermittent faults have been found in the study area. Based on strike and frequency, fracture system has been divided into three sets such as NNE-trending J1 ($NS-40^{\circ}E$), WNW-trending J2 ($N50^{\circ}-80^{\circ}W$), and ENE-trending J3 ($N60^{\circ}-90^{\circ}E$). According to analysis of fracture density, it is revealed as follows: (a) Jl is the combination of Y-, P-, and R-shear fractures due to the dextral strike-slip of the Beopgi Fault. (b) J2 is the preexisted fracture zone conducting the intrusion of granite. Two tensional fractures dipping to NNE and SSW respectively have been induced by intrusion of granite and followed crustal uplift. (c) J3 is the tensional fracture developed between Yangsan and Dongrae Faults having NNE trend and dextral strike-slip sense. This study aims to reduce environmental impact and insure stability of underground facilities and tunnels.