• The Journal of Engineering Geology
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• v.22 no.2
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• pp.157-171
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• 2012

The slope design of an open-pit mine must ensure slope stability and economic feasibility. The overall slope angle of the pit is therefore the main factor of concern because of limited support or reinforcement options available in such a setting. This study examines the optimal measurement system for monitoring the behavior of the slope in an open-pit mine using displacement measurement, data analysis, and numerical simulations for a coal mine at Pasir, Indonesia. The area of slope to be managed is extensive and the maximum displacement, as calculated by numerical analysis, is about 3,000 mm. The displacement data, measured by inclinometer and GPS, were analyzed, and the applicability of SSR (slope stability radar) was reviewed in comparison with other monitoring systems.

• Journal of the Korean Geotechnical Society
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• v.28 no.1
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• pp.5-15
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• 2012

This paper presents the results of an investigation into the pull-out characteristics of screw anchor piles for use in braced excavation and cut-slope. A series of reduced-scale model tests were performed on model screw anchor piles with different geometric characteristics such as screw size and pitch length. The results indicated that the pullout resistance increases with decreasing the pitch length for a given screw size. It was also observed that the pullout capacity of a screw anchor pile increases with the screw size up to a certain size beyond which the increase becomes minimal. The results are presented in such a way that the pullout characteristics of screw piles with different screw geometric characteristics can be identified. Practical implications of the findings are discussed.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.61-71
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• 2005

Cemented Sand and Gravel (CSG) is a material made by simple mixing of rock-based raw materials such as excavated soil and riverbed gravel together with cement and water. The use of CSG material for cofferdam and large dam is gradually increasing in Japan because a quarry and aggregate plants can be diminished. Also, the CSG method can reduce dam construction cost, construction duration and destruction of environment. In this paper, the basic strength characteristics of CSG, such as compressive strength, modulus of elasticity and stress-strain curve were investigated by unconfined compression test and large triaxial compression test. From the results of the experimental study, the correlation equations between elastic modulus and unit cement, age are proposed.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.163-176
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• 2017

The Discrete Element Method (DEM) has been widely used in civil engineering as well as various industrial fields to simulate granular materials. In this study, DEM was adopted to predict the performance of the face plate-type earth pressure balance (EPB) shield TBM (Tunnel Boring Machine). An analysis of the TBM excavation performance was conducted according to two pre-defined excavation conditions with the different rotation speeds per minute (RPM) of the cutterhead. The TBM model which was used in this study has a 6.64 m of diameter and six spokes. Also, 37 precutters and 98 scrapers at an each spoke were modeled with a real-scale specification. From the analysis, compressive forces at the cutterhead face, shield and cutting tools, resistant torques at the cutterhead face, muck discharge rate and accumulated muck discharge by the screw auger were measured and compared.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.113-118
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• 2017

Numerical analysis was carried out using a finite element analysis program to analyze the behavior characteristics of enlarged cylinder type anchor. It was found that the ultimate resistance of enlarged cylinder type anchor increases with the enlargement angle from numerical analysis for various enlargement angle cases. In the case of $30-60^{\circ}$ of enlargement angle, the deformation and stress distribution characteristics in anchor are similar regardless of enlargement angle. However, when the same tensile force is applied, there is a difference in the degree of frictional resistance because of difference of displacement of top of grouting zone. Also, it was found that the maximum compressive force and tensile force were generated at the cone of the upper portion of the grouting zone, and tensile fracture of the upper grouting portion is likely to occur.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.655-666
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• 2013

A number of highway projects are in progress in Korea to accommodate increasing transportation demands. As the highway route becomes more complex, some projects include tunneling through unconsolidated sedimentary rock. Since an unconsolidated sedimentary rock mainly consists of rock and ground mass, the behavior and characteristics in unconsolidated sedimentary rock tunnel are quite different from typical rock tunnel. However, construction case histories and rock classifications method on unconsolidated sedimentary rock tunnel had not been developed or studied domestically. Consequently the case studies and rock classification system for unconsolidated sedimentary rock are required to better understand its behavior for tunneling. In this study, rock mass classification method is proposed to identify unconsolidated sedimentary rock based on point load and slake durability tests. Based on this, the proposed method of unconsolidated sedimentary rock can be applied well through comparisons with the results of convergence measurement.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.259-259
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• 2018

최근 우리나라는 기후변화에 따른 태풍발생빈도 증가 및 이상강우, 유역내 토지이용의 고도화로 인한 유역특성 변화로 유역내 홍수량은 증가하고 홍수 도달시간이 짧아지는 양상을 보이고 있다. 이로 인해 홍수에 따른 치수방어 대책으로 하천의 제방축조 및 보강방법이 주로 채택되었으나, 최근에는 홍수시 직접적인 하천내 수위 저감을 위한 방안으로 하도내 저류효과를 확대하기 위한 보 설치 및 하도정비를 통한 하도준설을 시행하고 있다. 그러나 본류 하상저하에 따른 지류하천의 하상변동(두부침식)으로 하도내 세굴 침식에 의한 하천시설물 피해 사례가 늘게 되면서 과거 홍수에 의한 제방월류 피해에서 하상변동에 의한 하천시설물 붕괴로 하천피해 양상이 바뀌게 되었다. 이와 같은 피해를 방지하기 위해 지류하천 합류부에 하상변동 방지책으로 하상유지공을 설치하고 있지만 국내에는 이와 관련된 구체적 설계기준 및 연구가 미비하여 일선에서는 아직도 하천구조물의 용도가 다른 보나 낙차공의 설계기준을 준용하는 등 하상유지공 용도에 특성화된 설계기준(최적 위치선정 및 형식 등)이 없는 실정이다. 본 연구에서는 감천(낙동강 지류하천)유역내 하도준설 및 홍수로 인한 하상유지공의 유실에 따른 지류하천의 피해사례를 통해 수치해석결과 및 실측자료를 바탕으로 하상유지공 계획의 중요성을 검증하고자 하였다. 또한 하도준설로 생성된 지류합류부의 단차구간에 안정성을 확보한 최적의 하상유지공 위치 및 형식 등을 선정 검토하고 설치 유 무에 따른 유수흐름 및 하상변화양상을 비교 분석하였다. 본 연구의 결과를 토대로 향후 하도굴착 및 하상유지공 계획시 고려해야할 사항(지형현황 및 수리특성 등)을 인지하고 극한상황에서도 안전한 하상유지공의 위치 및 형식 등을 선정하는데 활용 가능할 것으로 판단된다.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.313-324
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• 2004

The finite element method and statistics of the convergence measurement are useful method of the stability analysis of the tunnel adjacent to the pier. It is the purpose of the this case study to certificate of validity of the application of those methods. The safety of the pilot tunnel method and LW pre-grouting has been evaluated from the FEM analysis. The three-dimensional finite element method is carried out for the decision of the level of stress redistribution at the two-dimensional numerical analysis. An analysis of the convergence is carried out by the estimation of preceding convergence at tunnel excavation. F-examination is applied for this estimation. As results of that analysis, The F-value is from 10.81 to 158.74 and the coefficient of determination is from 0.82 to 0.99. An analysis of convergence is carried out by using regression analysis. Consequently, it is shown that the convergence can be modeled as following function C(t) = a[1-exp(-bt)].

• Explosives and Blasting
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• v.38 no.4
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• pp.26-36
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• 2020

With the increase of expansion and use of the underground space, the possibility of an underground explosion by terrorists is increasing. In this study, after modeling a circular tunnel excavated at a depth of 50m, an explosion load was applied to the inside of the tunnel. As for the explosion load, the explosion load of the maximum explosive amount for six types of vehicle booms proposed by ATF (Bureau of Alcohol, Tobacco, and Firearms) was calculated. For the rock mass around the circular tunnel, three types of rock grades were selected according to the support pattern suggested in the domestic tunnel design. Nonlinear dynamic analysis was performed to evaluate the influence of the ground structure by examining the surface displacement using the explosion load and rock mass characteristics as parameters. As a result of the analysis, for grade 1 rock, the influence on the uplift of the surface should be considered, and for grade 2 and 3 rocks, the influence on a differential settlement should be considered. In particular, for grade 3 rocks, detailed analysis is required for ground-structure interaction within 40m. Also, it is considered that the influence of Young's modulus is the main factor for the surface displacement.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.21-25
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• 2011

This study was performed to evaluate characteristics of illegally dumped wastes in the riversides of Nakdong river found during dredging of Nakdong river. Precise classification of the wastes found in the riversides is essential to proper treatment of the wastes. We tried to determine whether these wastes contained toxic compounds and stabilized. Wastes were found at 27 sampling points out of 159 segments investigated and these wastes were not classified as toxic wastes. In addition, clay soils were found at 60 sampling points, and these soils were not classified as wastes. Thus, these soils are thought to be recycled as construction materials. Some samples were not stabilized, which means biodegradation was still progressed in these areas.