• The Journal of Engineering Geology
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• v.10 no.3
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• pp.273-275
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• 2000

Engineering Geology를 필자는 지질공학(地質工學)이라 한다. 지질공학은 지반(地盤)의 토질 및 암석의 거동을 역학적인 관점에서의 지질역학(地質力學, Mechanical Geology)과 공학적 판단을 가하여 실제의 공사 등에 응용되는 기초학문이다. 이 분야에서의 중요 부분은 토목 시공 과정 또는 시공후에 발생할수 있는 지질적 문제(지질약선대의 문제 및 지질역학적 문제)등 에 대한 조사연구인 것이다. 따라서 지질공학자는 암반의 기계적인 응답에 대한 요소들을 지질도에 표시하여 시공상의 문제점을 검토, 연구하여 착공여부를 결정하고 지반보강 또는 지질개선을 실시케한다. 문제 중 지반의 거동은 물질 자체의 성질과 불연속성면에 있다. 물질자체의 성질은 입자의 크기에 있고 구조적 집합성에 있는 것이다. 불연속성면은 미세한 균열에서 거대한 단층면에 이르기까지 존재하며, 구조지질역학적 성격에 있다. (중략)

• Tunnel and Underground Space
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• v.7 no.4
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• pp.299-309
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• 1997

Soil and rock improvement and reinforcement techniques are applied to achieve safe tunnel excavation in difficult geological conditions. The Umbrella Arch Method(UAM), one of the auxiliary techniques, is used to reduce ground permeability and improve stabtility of the tunnel by inserting a series of steel pipes into ground around the crown inclined to the longitudinal axis of the tunnel. Additionally, multi-step grouting is added through the steel pipes. UAM combines the advantages of a modern forepoling system with the grouting injection method. This technique has been applied in subway, road and utility tunneling sites for the last few years in Korea. This paper presents the results of analysis of the case studies on ground movements associated with UAM used in the Seoul Subway line 5 constructon site. Improvement of tunnel stability and decrease of ground settlement expected with pipe insertion are also discussed. Finally, the method to minimize ground settlements caused by NATM tunnelling are suggested.

• Tunnel and Underground Space
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• v.6 no.4
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• pp.298-305
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• 1996

Grouting technique is frequently used where a tunnel structure is passing through the shallow overburden area or where the thickness of hard rock above the tunnel is rather thin. However, engineering background on design process of the grout reinforcement does not seem to be fully understood until now. Mechanics of composite material is, therefore, introduced in this study to investigate the orthotropic material properties of the composites containing soil(or rock) and grouting material. These orthotropic material properties can be used to represent the reinfocement effects quantitatively. The model developed in this study is next applied to a typical tunnel structure and the grouting effect is analyzed numerically. The idea used in this study can be expanded to a situation where a pipe roofing or a forepoling technique is adopted and a simplified design procedure, similar to the model model introduced in this study, can be developed.

• Tunnel and Underground Space
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• v.27 no.6
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• pp.393-405
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• 2017

This report is intended to be used as a reference in the project being conducted by MIRECO for preventing ground subsidence in mining district. For this purpose, the procedure of the project for preventing ground subsidence mining district was described and cases of design, construction, and study were introduced.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.424-430
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• 2001

현대건설(주)는 사업 주관사로서 해외 업체와 대만고속전철 턴키 공사를 2000 년 1 월에 공동으로 수주하였다. 고속전철의 총 연장 길이는 약 326 km 이며, 정거장 10 개소, Depot 및 야적장으로 구성되어 있다. 이번에 수주한 공구는 2 개의 연속된 공구 (C230, C240) 이며, 본 논문은 총 연장 23.6km 인 C230 공구에 대한 설계 과정을 수록하였다. C230 공구는 NATM 터널 (6.2km), Cut-and-Cover 터널 (0.5km), 교량 (7.8km) 및 토공 구간 (9.1km)으로 구성되어 있다. 전 구간의 지반조건은 "매우" 취약한 매질로 구성되어 있으며, 층리나 절리는 거의 발달되어 있지 않다. 따라서 화약발파에 의한 터널 굴착은 기계식 굴착 (Back-hoe Excavation) 방법에 비하여 현실성이 없는 것으로 분석되었다. 취약한 지반에서 계측 결과를 기준으로 굴착 공간을 안전하게 유지할 수 있는 NATM 보강 설계가 현지 암반조건에 가장 이상적인 방법으로 제시되었다. 특히, NAT설계는 대형 아파트 지역과 파쇄대 및 지하수 침투 예상지역을 통과하기 위하여 계측에 의한 Feed-back 과정을 탄력적으로 적용하도록 계획하였다.

• Korean Journal of Agricultural Science
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• v.35 no.2
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• pp.213-223
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• 2008

The instability of rock slopes caused by heavy rainfall and soil mass sliding needs the preventable and reinforcing method. The most important factor for the stability is the shear strength available in the planar part of the failure surface, which shows that a progressive failure takes place and a reinforcing of rock slope using FRP grout is effectively available. In this study, a grouting bolting interval predictions by limit equilibrium analysis and Matlab mathematical computer codes in several cases is presented for FRP reinforced rock slope. The proposed mathematical computer code can be easily applied for seeking properly FRP grout intervals prior to design and execute a reinforcement of a rock slope in practice.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1369-1375
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• 2006

This study analyzes stability and the reason of slope failure about cut slope on stony mountain in Acheondong, Guri and suggests the reasonal reinforce method. Based on the results of the subsurface exploration, laboratory tests, and the numerical analysis of finite element method, the potentials of plane and wedge failure are highly estimated. The safety factor was 1.2 under dry and 1.06 wet condition. The most proper reinforce method to raise the safety factor more than 1.5 was the way to control displacement by using step retaining wall, earth anchor, wire mesh, and rock anchor.

• Tunnel and Underground Space
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• v.20 no.4
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• pp.267-276
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• 2010

In modern rock engineering practice, fully grouted rock bolting is actively employed as a major supporting system, so that understanding the behavior of fully grouted rock bolts is essential for the precise design of rock bolting. Despite its importance, the supporting mechanism of rock bolts has not been fully understood yet. Since most of existing analytical models for rock bolts were developed by drastically simplifying their boundary conditions, they are not suitable for the bolts of in-situ condition. In this study, 3-D elastic FE analysis of fully grouted rock bolts has been conducted to provide insight into the supporting mechanism of the bolt. The distribution of shear and axial stresses along the bolt are investigated with the consideration of different boundary conditions including three different displacement boundary conditions at the bolt head, the presence of intersecting rock joints, and the variation of elastic modulus of adjacent rock. The numerical result reveals that installation of the faceplate at the bolt head plays an important role in mobilizing the supporting action and enhancing the supporting capabilities of the fully grouted rock bolts.

• Journal of Conservation Science
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• v.17 s.17
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• pp.83-94
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• 2005

Host rock or the standing sculptured Buddha in the Yongamsa temple is macular porphyritic biotite granite, which has gone through mechanical and chemical weathering. The rock around the Buddha statue is busily scattered with steep inclinations that are almost vertically discontinuous planes with the strikes of $N8^{\circ}E$. Especially the development of the joints that cross the major joints causes the structural instability of the rock. The rock of the Buddha statue is separated into several rock blocks because of many different discontinuity. Thus it is estimated that the bed rock has not only plane and toppling failure but also wedge failure in all the sides. Since the differential pressure is imposed on the body of the Buddha in the host rock, it is urgent to give a reinforce treatment of geotechnical engineering for the safe of its structural stability. Very contact area of joints have turned into soil, which promotes the growth of weeds and plant roots, then aggravates the mechanical weathering of the rock. Thus conservational treatments should also be considered to get rid of secondary contaminants and vegetation along the discontinuities and to prevent further damages.

• Journal of Conservation Science
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• v.26 no.2
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• pp.121-132
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• 2010

The Bukjiri Maaeyeoraejwasang (National Treasure No. 201) consists of two-mica granite in medium size, which was the simbol of power in the region of the Silla period. Magnetic susceptibility of the host rock was measured as 0.41(${\times}10^{-3}$ SI unit), which has the similar range with surrounding outcrop. The Buddha developed parallel discontinuous plane of NE to SW strike and damaged seriously by exfoliation, granular disintegration and brown discoloration as 41.5%, 16.7% and 40.0%, respectively. As a result of the ultrasonic velocity, which was relatively weak values as 1,629m/s (Buddha area) and 1,549m/s (surrounding outcrop), improved about 900m/s compared to last treatment. From the results of the evaluation for slope stability, identified the possibility of toppling failure in the Buddha, and planar and wedge failure in host rock. Therefore, we suggest for the safely conservation of the Buddha, continuance monitoring for understand behavior of discontinuity system of the surface, and necessitate foundation reinforcement method for the rock which has the danger of collapse.