• Journal of the Korean Geotechnical Society
• /
• v.16 no.5
• /
• pp.117-127
• /
• 2000

터널 시공과 굴착과정에서 파쇄대, 절리, 연약대, 균열 등 암반에서의 불연속면은 중요한 역할을 한다. 본 연구에서는 지반 고유의 특징인 불확실성에 의한 터널 설계와 시공 과정에서 겪는 많은 시행오차를 최소화하기 위해서 국내의 터널 붕락 현장의 지반조사 자료를 분석하여 터널 붕락 유형 및 규모를 제시할수 있는 Geo-predict 시스템을 개발하였다. Geo-predict 시스템은 총 104개 터널 붕괴/붕락자료(국외84개, 국내20개)를 분석한 자료를 테이터베이스로 인공신경망 학습을 토해서 터널 붕괴 형태와 규모를 추론하는 시스템이다. 본 논문에서는 Geo-predict의 개발과정 및 구성.기능을 소개하였으며 104개 터널 현장 자료를 지반조건별로 분석하고 이를 데이터베이스화하여 인공신경함을 이용한 추론 시스탬을 구축하고, 2개 고속전철 터널현장과 1개 지하철 시공현장에 적용성 평가를 실시하여, 터널의 붕락 가능 및 붕락 규모를 추론하였다.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.5 no.1
• /
• pp.15-20
• /
• 1995

Fuzzy membership functions are some kinds of mapping function for the fuzzification and the defuzzification. Triangle-shaped fuzzy membership functions are widely used in fuzzy controller, for it is easy to implement. In these membership functions, it is known that narrower fuzzy sets permit finer control near the operating point than that far from the operating point. $Supp{\acute{o}}se$ we have a membership function with narrower triangle near zero and wider triangle far from zero. The membership function will make fine control when small input is given and rough control at large input. Therefore the performance of the controller with that membership function will be enhanced. This paper presents how the width of triangle base in the fuzzy membership function has influence on the output using geometrical approaches.

• The Journal of Engineering Geology
• /
• v.12 no.3
• /
• pp.295-303
• /
• 2002

The stability of rock slopes is closely related to the factors such as: type of rock, development of geological structures, weathering, characteristics of rock, and the shape of the geological features. When we design the rock slope, the slope stability is determined by the discontinuity causing the circular, plane or wedge failure. The failure happens when the slope is under the unstable geological condition. But in some cases, slope failure has occurred even though the slope is under stable geological conditions. In this respect, this paper presents the plane failure conditions for domestic rock slopes through research of sites where slope failure has occurred regardless of whether or not it satisfied the stable geological conditions.

• Tunnel and Underground Space
• /
• v.16 no.5 s.64
• /
• pp.368-376
• /
• 2006

After heavy rainfall, It was occurred massive plane failure along bedding plane of shale in the center of rock slope. It was observed filling material and trace of underground water leakage around of the slope. We tried to find the cause for slope failure, and the result of examination showed that primary factors of the failure were low shear strength of clay filling material and water pressure formed within tension crack existed in the top of the slope. In this research, in order to examine the features of shear strength of filled rock joint, shear test of filled rock joint was conducted using of artificial filling material such as sand and clay..Also we made an investigation into the characteristics of shear strength with different thickness of filling materials.

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

• The Journal of Engineering Geology
• /
• v.21 no.2
• /
• pp.125-131
• /
• 2011

The discharge characteristics of the Seodo Mulgol Spring-the only groundwater-producing area in Dokdo-were evaluated by measurements of discharge rate and electrical conductivity (EC) on five occasions. The Seodo Mulgol Spring is fed by rainfall in upstream areas of the Mulgol cave, and the rainwater of the area moves down along cooling joints developed in trachyandesite II and trachyte, finally discharging at the Mulgol cave. The discharge rate of the Seodo Mulgol Spring varied from 1.12 to 7.02 $m^3/d$ during the study period and EC varied from 2,650 to 3,390 ${\mu}S/cm$, showing a sharp increase during heavy rainfall. The observed variations in discharge rate and EC at the Seodo Mulgol Spring are attributed to the relatively short distance between the recharge area and the Mulgol cave, and to the rapid movement of groundwater through columnar joints developed in trachyandesite II and trachyte. Additional discharge measurements, combined with precise rainfall data, are required at Dokdo to elucidate the discharge characteristics of the Seodo Mulgol Spring.

• Tunnel and Underground Space
• /
• v.29 no.6
• /
• pp.508-522
• /
• 2019

Because of the slope failure, not only property damage but also human damage can occur, slope stability analysis should be conducted to predict and reinforce of the slope. This paper, defines the ground areas that can be characterized in terms of slope failure such as Rockmass jointset, Rockmass fault, Soil, Leakage water and Crush zone in sloped images. As a result, it was shown that the deep learning instance segmentation network can be used to recognize and automatically segment the precise shape of the ground region with different characteristics shown in the image. It showed the possibility of supporting the slope mapping work and automatically calculating the ground characteristics information of slopes necessary for decision making such as slope reinforcement.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.2
• /
• pp.23-37
• /
• 2002

Failure of the cut slope is triggered by combination of internal and extemal failure factors. Internal failure factors are related to geological and geometrical conditions of slope itself, and natural and/or artificial loadings on slope can be the external failure factors. Influences of these failure factors show different intensity according to the ground condition and are controlled by behavior characters of the slope. In this study, the soil depth ratio(SR), block size ratio(BR) and rock strength are used as the criteria to divide ground condition based on behavior characteristics. Ground condition of the slope is divided into discontinuous jointed rock mass and continuos soil-like mass, highly fractured rock mass and massive rock mass by the criteria(SR and BR). The SFi-system is a rating system to determine the slope failure index(SFi) by analyzing internal and external factors based on classification of the ground condition. The results of the SFi-system application to the real cut slopes show close relationship between the SFi value and potential or dimension of the failure. Therefore, the SFi-system can be used as a useful tool to predict and analyze the characteristic of the slope failure.

• Explosives and Blasting
• /
• v.27 no.1
• /
• pp.47-52
• /
• 2009

Blasting is necessary for excavation processes since more than 70% of korean land is consist of mountains. The vibration and noise accompanied by blasting processes usually bring about public complaints. Blasting patterns are chosen by economical efficiency, stability and construction conveniency. However, there are many alternatives without control to settle the popular complaint. To prevent those alternatives, standard blasting method for design and construction were suggested by MLTM (Ministry of Land, Transport and Maritime Affairs) in 2006. However, standard blasting pattern of MLTM was designed in a lump irrespective of types of rocks. Economical loss may occur by ignoring the characteristics of rocks for the applications to the rocks with low intensity, such as shale, or containing many joint. We deduced some economical progresses by performing test blasting with adjusted drilling spacing and length of burden considering the characteristics of local rock. This paper suggests the start of case studies for different applications. Economic improvement can be expected by applying those results deduced from case studies to design and construction.

• Tunnel and Underground Space
• /
• v.8 no.4
• /
• pp.296-306
• /
• 1998

Ongoing huge Bakun Hydropower project is including the construction of a 210 m height hydroelectric rockfill dam with an installed capacity of 2,520 MW and a power transmission system connecting to the existing networks between Sarawak and peninsula Malaysia. In order to allow the main dam construction during the dry season, the Ballui river will have to be detoured through 3 concrete lined diversion tunnels with an internal diameter of 12 m and a length of 1,400 m each. The geology of Bakun site belongs to the several thousand meters thick Belaga formation deposited from the late Cteteceous to the early Teriary in the Northwest Borneo geosyncline. The orientation of the bedding plane, strike at N55$^{\circ}$E to N70$^{\circ}$E and dip at 50$^{\circ}$SE to 70$^{\circ}$SE, is developed uniformly in Bakun sedimentary rocks. Rock mechanical characteristics of Bakun site have been classified into 4 rock mass types(RMT) depending on the degree of weathering and the occurrence of rock jointing with RMR. Graywacke(Sandstone) as well as Shale can take place together in the same rock mass type if their rock mass properties are similar. It was summarized the rock support type and support system design of underground diversion tunnels in view of rock mechanics.