• The Journal of Engineering Geology
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• v.26 no.2
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• pp.187-196
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• 2016

We conducted three-dimensional finite element analysis to predict the presence of upcoming fault zones during tunneling. The analysis considered longitudinal displacements measured at tunnel face, and used 28 numerical models with various fault attitudes. The x-MR (moving range) control chart was used to analyze quantitatively the effects of faults distributed ahead of the tunnel face, given the occurrence of a longitudinal displacement. The numerical models with fault were classified as fault gouge, fault breccia, and fault damage zones. The width of fault cores was set to 1 m (fault gouge 0.5 m and fault breccia 0.5 m) and the width of fault damage zones was set to 2 m. The results, suggest that fault centers could be predicted at 2~26 m ahead of the tunnel face and that faults could be predicted earliest in the 45° dip model. In addition, faults could be predicted earliest when the angle between the direction of tunnel advance and the strike of the fault was smallest.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.193-200
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• 2002

울산광역시 울주군 삼남면 가천리와 상천리 일원에 발달하는 양산단층대 중남부의 발달특성과 제4기단층을 기재한다. 이 지역에는 중생대 백악기의 퇴적암과 화강암의 경계부 근처에 양산단층대의 주단층대와 부단층대로 확인되는 대규모의 단층파쇄대가 북북동-서남서 내지 남-북의 주향에 거의 수직으로 발달하고 있다. 단층조선은 수평에 가까우며 단층대내의 구조에 의하면, 주로 우향의 주향이동운동이 우세하다. 한편, 상천리와 가천리에는 이들 기반암과 제4기의 하성 사력층의 경계부 부근에서 제4기단층이 2조 발달하고 있다. 이들은 가천 제1단층과 가천 제2단층으로 기존의 양산단층대 일부가 제4기에 재활동한 것으로, 북북동 방향의 주향에 동측으로 고각의 경사를 보인다 단층조선은 거의 수평이며, 제4기 역들이 단층끌림에 의해 배열된 상태나 단층엽리내의 구조에 의하면 우향의 주향이동성운동이 우세하다.

• Journal of the Korean Geophysical Society
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• v.3 no.4
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• pp.245-250
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• 2000

By using amplitude ratios (SV/P, SH/P, SV/SH) and P and S wave polarities, we obtained fault plane solutions of the June 26, 1997 Kyong-ju earthquake. The solutions show $150{\pm}4^{\circ}$ in strike, $63{\pm}6^{\circ}$ in dip and $65{\pm}7^{\circ}$ in rake, or $18{\pm}12^{\circ}$ in strike, $26{\pm}3^{\circ}$ in dip and $120{\pm}5^{\circ}$ in rake. This result implies the stress field trending ENE-WSW, which is remarkably consistent with the previous results obtained from the moment tensor inversion, and from the composite fault plane solution for the events occurred around the Yangsan fault area.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.393-401
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• 2016

In the present study, fault attitudes and the locations of appearance of faults in tunnel faces were predicted by analyzing the trajectory of the maximum longitudinal displacement immediately before the appearance of faults through three-dimensional finite element analysis. A total of 28 fault attitude models were used in the analysis. Those faults that have drives with dip appear first in the upper part of tunnel faces as tunnel excavation progresses and their maximum longitudinal displacement shows a tendency to move from the middle part to the upper part of tunnel faces. Those faults that have drives against dip appear first in the lower part of tunnel faces as tunnel excavation progresses and their maximum longitudinal displacement shows a tendency to move from the middle part or middle upper part to the lower part of tunnel faces. In addition, when the dip of faults is larger the maximum longitudinal displacement moves from the left upper part toward the wall part in the case of drive with dip models and from the left lower part toward the wall part in the case of drives against dip models. Therefore, it was indicated that the attitudes of faults distributed ahead of tunnel faces and the locations where faults appear in tunnel faces can be predicted by analyzing the longitudinal displacement trajectory of tunnel faces following excavation.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.113-121
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• 2012

The mechanical characteristics of a fault gouge from near Mt. Kumjung in Kumjung-Gu, Busan, were estimated from laboratory tests on different joint models. Fault gouge samples and joint samples in biotite granite were obtained from boreholes in the study area that had penetrated small faults associated with the Dongnae and Yangsan faults. XRD and SEM analyses revealed that for the fault gouge consists of several clay minerals with tabular structure (kaolinite, montmorillonite, illite, sericite), which could cause the considerable reduction of shear strength when wet. The shear strength of the fault gouge was obtained from direct shear tests of the fault gouge itself and from direct shear tests of several natural/artificial joint surfaces coated with fault gouge. The results indicate that the reduction of shear strength is more abrupt for the joint surfaces coated with fault gouge compared with uncoated joint surfaces, and that the friction angle of the fault gouge between joint surfaces is much lower than the internal friction angle of the fault gouge itself. Fault gouges in contact with rock, therefore, could have a stronger negative effect on the stability of structures in rock masses than the fault gouge itself.

• The Journal of the Petrological Society of Korea
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• v.18 no.1
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• pp.19-30
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• 2009

The main fault of Yangsan Fault Zone (YFZ) and Quaternary fault were found in a trench section with NW-SE direction at an entrance of the Sinheung village in the northern Eonyang, Ulsan, Korea. We interpreted the movement history of the southern part of the YFZ from the geometric and kinematic characteristics of basement rock's fault of the YFZ (Sinheung Fault) and Quaternary fault (Quaternary Sinheung Fault) investigated at the trench section. The trench outcrop consists mainly of Cretaceous sedimentary rocks of Hayang Group and volcanic rocks of Yucheon Group which lie in fault contact and Quaternary deposits which unconformably overlie these basement rocks. This study suggests that the movement history of the southern part of the YFZ can be explained at least by two different strike-slip movements, named as D1 and D2 events, and then two different dip-slip movements, named as D3 and D4 events. (1) D1 event: a sinistral strike-slip movement which caused the bedding of sedimentary rocks to be high-angled toward the main fault of the YFZ. (2) D2 event: a dextral strike-slip movement slipped along the high-angled beddings as fault surfaces. The main characteristic structural elements are predominant sub-horizontal slickenlines and sub-vertical fault foliations which show a NNE trend. The event formed the main fault rocks of the YFZ. (3) D3 event: a conjugate reverse-slip movement slipped along fault surfaces which trend (E)NE and moderately dip (S)SE or (N)NW. The slickenlines, which plunge in the dip direction of fault surfaces, overprint the previous sub-horizontal slickenlines. The fault is characterized by S-C fabrics superimposed on the D2 fault gouges, fault surfaces showing ramp and flat geometry, asymmetric and drag folds and collapse structures accompanied with it. The event dispersed the orientation of the main fault surface of the YFZ. (4) D4 event: a Quaternary reverse-slip movement showing a displacement of several centimeters with S-C fabrics on the Quternary deposits. The D4 fault surfaces are developed along the extensions of the D3 fault surfaces of basement rocks, like the other Quaternary faults within the YFZ. This indicates that these faults were formed under the same compression of (N)NW-(S)SE direction.

• Journal of the Korean earth science society
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• v.28 no.2
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• pp.202-213
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• 2007

The Odaesan earthquake $(M_L=4.8)$ occurred near Mt. Odae, Jinbu-Myon, Pyongchang-Gun, Kangwon Province on January 20, 2007. It has a shallow focal depth about 10 km. Its felt area covers most of the southern peninsula except some southern and western inland area. The maximum MM intensity was VI in the areas including Jinbu, Doam, Kangreung, Jumunjin, and Pyongchang. In these areas, there was a very strong shaking that caused several cracks on the walls of buildings and houses, slates falling off the roof, tiles being off the wall, things falling off the desk, and rock falling from the mountains. In order to get fault plane solutions, grid searches were performed by fitting distributions of P-wave first-motion polarities and SH/P amplitude ratios for each event. The results showed that the main shock represented right-lateral strike-slip sense and two aftershocks, reverse sense. It seems that the seismogenic fault may be the NNE-SSW trending Weoljeongsa fault near the epicenter based on the distribution of epicenters (foreshock, main shock, and aftershocks), damage area, and fault plane solution. The distribution of the epicenters indicates that the length of the subsurface rupture is estimated to be about 2 km.

• Proceedings of the Speleological Society Conference
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• 1996.09a
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• pp.77-78
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• 1996

카르스트는 특이한 수문학적 용식지형이며, 암석의 높은 용식성으로 인해 발달된 암석의 공극(1차적 삼투)과 암석의 구조적 변형인 절리면, 균열면, 단층면, 층리면 등(2차적 삼투)의 확장으로 인하여 발생되어진 경관을 총칭한 것이다. 암석의 용식성만으로 카르스트가 형성된다는 것을 설명하기는 쉽지 않다. 왜냐하면 암석의 구조적인 특성이 중요한 인자이기 때문이다.(중략)

• Tunnel and Underground Space
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• v.21 no.4
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• pp.251-263
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• 2011

The geomechanical characteristics of rock and the structural geological feature of the fault should be studied and examined for the successful construction of large-span tunnel. In this case study, that is a important case for the tunnel collapse and reinforcement during the construction for the waterway tunnel at large thrust fault zone in schist, we carried out geological and geotechnical survey for make the cause and mechanism of tunnel collapse. Also, we have designed the reinforcement and re-excavation for the safe construction for collapse zone and have carried out successfully the re-excavation and finished the final concrete lining.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.403-411
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• 2016

A three-dimensional finite element analysis was conducted to analyze the predictable distances of a fault zone by using longitudinal displacement on tunnel face, trend line, L/C ratio, and C/C₀ ratio at tunnel crown. The analysis used 28 numerical models with various fault attitudes. As a result, those faults that have drives with dip could be predicted earliest in L/C and C/C₀ ratio analysis. And those faults that have drives against dip could be predicted earliest in L/C ratio and longitudinal displacement analysis. In addition, the fault zone ahead of tunnel was predicted in most models by using longitudinal displacement, trend line, L/C ratio, and C/C₀ ratio. However, the longitudinal displacement among these methods may be most usefully predict a fault zone since it is displacements can be measured immediately after tunnel excavation.