• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2007년도 특별심포지엄 논문집
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• pp.63-79
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• 2007

Several remedial works were attempted to stabilize the collapsed area of the inlet slopes of diversion tunnel, but prevention of any further movement was being only carried out at beginning stage by filling the area with aggregates and rock debris, after several cracks had been initiated and developed around the area. The extra specialty developed folding zone is consisted with highly weathered Greywacke and Black shale. The suggested solution is to improve the properties of the rock mass of failed area by choosing the optimum level of reinforcement through the increment of slope rock support design so as to control the movement of slopes during the re-excavation. The Bakun hydroelectric project includes the construction of a hydroelectric power plant with an installed capacity of 2,520MW and a power transmission system connecting to the existing transmission networks in Sarawak and Western Malaysia. The power station will consist of a 210m height Concrete Faced Rockfill Dam. During the construction of the dam and the power facilities the Balui River has to be diverted of the tunnels is 12m and the tunnel width is 16m at the portal area. This paper describes the stability analysis and design methods for the open cut rock slopes in the inlet area of the diversion tunnels. The geotechnical parameters employed in stability calculations were given as a function of four defined Rock Mass Type (RMT) which were based on RMR system from Bieniawski. The stability calculations procedure of the rock slopes are divided into two stages. In the first stage, it is calculated for the stability of each "global" slope without any rock support and shotcrete system. In the second stage, it is calculated for each "local" slope stability with berms and supported with rock bolts and shotcrete. The monitoring instrumentation was performed continuously and some of the design modification was carried out in order to increase the safety of failed area based on the unforeseen geological risks during the open cut excavation.

• Geomechanics and Engineering
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• 제23권1호
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• pp.85-92
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• 2020

This study adopted soil test and laboratory physical model experiments to simulate the tailings impoundment accumulation process according to the principle of similarity. Relying on the practical engineering, it analyzed the tailings deposition characteristics on dry beach surface during the damming process, as well as the variation rules of dam saturation line. Results suggested that, the tailings particles gradually became finer along the dry beach surface to inside the impoundment. The particle size suddenly changed at the junction between the deposited beach and the water surface, which displayed an obvious coarsening phenomenon. Besides, the deposited beach exhibited the vertical feature of coarse upward and fine downward on the whole. Additionally, in the physical model, the saturation line elevated with the increase in dam height, and its amplitude was relatively obvious within the range of 1.0-4.5 m away from the initial dam. Under flood condition, the saturation line height was higher than that under normal condition on the whole, with the maximum height difference of 4 cm. This study could provide an important theoretical basis for further studies on dam failure experiments and the evolution rules of leaked tailings flow.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1994년도 수공학연구발표회논문집
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• pp.309-315
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• 1994

• 한국대기환경학회지
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• 제8권2호
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• pp.138-145
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• 1992

Dependence of the standard deviation of wind direction fluctuations, ${\sigma}_{\theta}$, on atmospheric stability, averaging time and topography were analysed with the data measured at three sites, Youngjongdo beach of the Yellow Sea, Chuncheon basin and Doam-Dam valley. The results show that the mean value of ${\sigma}_{\theta}$ is large in complex terrain, the Doam-Dam site. It is notable that the large value of ${\sigma}_{\theta}$ at night is associated with the low wind speed and the strong stable condition. In order to study the long-period fluctuations of the wind direction, ${\sigma}_{\theta}$ for longer than 10 minutes averaging time was further analysed using the data obtained at the Chuncheon basin. At the averaging time shorter than 60 minutes, larger ${\sigma}_{\theta}$ is associated with longer averaging time in the strong stable condition. However, ${\sigma}_{\theta}$ was not affected significantly by wind speed and averaging time in neutral conditions. The results of the spectrum analysis for the time series data of wind direction showed that low-frequency fluctuations ranging from 10 to 60 minutes were dominated at the Chuncheon basin in strong stable condition.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.119-126
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• 2002

Fractures, especially faults have most significant influence on the difficulties encountered in various engineering and mining works, because they can give rise to inevitable reductions in shear strength as well as large increase in permeability. Thus, before underground access is possible, it is desirable to estimate the distribution and geometry of fractures in advance, if reliable structural data from e.g. Televiewer tool are available. To this end, fracture face mapping is just the evaluation method used to form a fracture image determined by intersecting of each fracture plane with a selected plane section of a rock mass, assuming that all fractures be planar with fixed-aperture. Although many fractures are geometrically complex and others are altered chemically, according to the abundant experiments in recent years, it would seem that the technique could be applied to benefit the design of numerous engineering works such as slope stability, tunnel excavations, dam foundation and diverse environmental works. This paper presents at first an evaluation algorithm for fracture face mapping and then concludes with various representative examples of applications.

• Geomechanics and Engineering
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• 제6권6호
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• pp.545-560
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• 2014

For slope stability analysis, an alternative to the classical limit equilibrium method (LEM) of slices is the shear strength reduction method (SRM), which can be integrated into finite element analysis or finite difference analysis. Recently, probabilistic analysis of earth slopes has been very attractive because it is capable to take the soil uncertainty into account. However, the SRM is less commonly extended to probabilistic framework compared to a variety of probabilistic LEM analysis of earth slopes. To overcome some limitations that hinder the development of probabilistic SRM stability analysis, a new procedure based on recursive algorithm FORM with sensitivity analysis in the space of original variables is proposed. It can be used to deal with correlated non-normal variables subjected to implicit limit state surface. Using the proposed approach, a probabilistic finite element analysis of the stability of an existing earth dam is carried out in this paper.

• 지질공학
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• 제30권3호
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• pp.279-288
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• 2020

샌드댐이란 하천의 횡단에 보 등을 설치하고 확보된 공간에 모래와 같은 투수성 재료와 물을 함께 채운 후, 공극내의 물을 저장하여 사용하기 위한 구조물이다. 주로 아프리카 케냐를 중심으로 많은 사례가 보고되고 있는 샌드댐에 관해 본 연구에서는 샌드댐의 구조적 안전과 취수량 증대를 위한 설계 방안을 제시하였다. 첫째, 샌드댐의 콘크리트 벽체의 안정성을 확보하기 위해 철근을 가시철근으로 연결, 시공의 편리함을 제시했다. 둘째, 지오텍스타일을 이용하여 증발을 45%에서 8%로 감소시킬 수 있었고 수평방향 투수배출량도 크게 줄일 수 있어 취수량은 기존대비 약 2.4배 증가되는 것을 알 수 있었다. 이 밖에도 수질개선을 위한 침사지 설계로 여과효율을 높였고, 토양수분장력계를 통한 모니터링 방법도 제시하였다.

• 한국지반신소재학회논문집
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• 제12권1호
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• pp.63-72
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• 2013

필댐의 안정성은 댐 축조시 주재료로 활용되는 조립재료인 암석존(rock zone)의 공학적 거동에 의존하므로 조립재료인 rockfill 재료의 전단강도 뿐만 아니라 하중-변형 특성(stress-strain characteristics)을 보다 정확히 이해하여야 한다. 또한, 댐 제체의 거동을 예측하고 수치해석적으로 분석하기 위해서는 조립재료의 거동을 모사하기에 적합한 구성모델을 활용하기 위한 물성값 분석 및 모델 파라미터의 캘리브레이션 연구가 필요하다. 본 논문에서는 부항댐 제체 재료에 대한 대형삼축압축 실험결과를 분석하고 이를 기반으로 조립재료에 대한 구성모델 파라미터들을 분석하였다. 부항댐 제체 재료를 고밀도와 저밀도로 구분하여 시료를 제작하고 다양한 구속압으로 수행된 실험결과와 캘리브레이션 된 구성모델 시물레이션 결과를 상호 비교한 결과 MD 모델이 조립재료의 응력-변형률 거동을 효과적으로 모사할 수 있음을 파악하였다.

• 한국안전학회지
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• 제35권5호
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• pp.30-38
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• 2020

In order to construct a dam, the diversion facility such as cofferdam and a diversion tunnel should be installed in advance. And size of a cofferdam depends on type of a main dam. According to the Korea Dam Design Standard, if the main dam is a concrete dam, design flood of the cofferdam is 1~2 years flood frequency. This means that overflow of the cofferdam occurs one time for 1 or 2 years, therefore, stability of the cofferdam should be secured against any overflow problem. In this study, failure probability analysis for the concrete cofferdam is performed considering the overflow. First of all, limit state function of the concrete cofferdam is defined for overturning, sliding and base pressure, and upstream water levels are set as El. 501 m, El. 503 m, El. 505 m, El. 507 m. Also, after literature investigation research, probabilistic characteristics of various random variables are determined, the failure probability of the concrete cofferdam is calculated using the Monte Carlo Simulation. As a result of the analysis, when the upstream water level rises, it means overflow, the failure probability increases rapidly. In particular, the failure probability is largest in case of flood loading condition. It is considered that the high upstream water level causes increase of the upstream water pressure and the uplift pressure on the foundation. In addition, among the overturning, the sliding and the base pressure, the overturing is the major cause for the cofferdam failure considering the overflow.

• 환경생물
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• 제37권4호
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• pp.664-671
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• 2019

낙동강 상류의 지류이며, 국내 대표적인 모래하천으로 잘 알려진 내성천 상류에 위치한 영주댐을 기준으로 하류 지점과 상류 지점을 선정하여, 2015년과 2016년동안 담수화에 따른 저서성대형무척추동물의 서식유형 및 군집구조의 변화 양상에 대한 분석을 실시하였다. 조사는 댐의 건설이 저서성대형무척추동물에 미치는 영향을 파악하고자 2015년, 2016년 총 4회에 걸쳐 실시하였다. 조사 결과, 댐에 의한 내성천의 담수화가 2016년 7월부터 진행됨에 따라 전체 출현 종수가 감소하였다. 특히 댐에서 가까운 상류 지점인 St.2와 St.3에서 감소 폭이 크게 나타났다. 유수성 환경과 입자가 큰 하상구조를 선호하는 E.P.T. 분류군의 종조성 비율은 감소하고, 정수역 환경을 선호하는 O.C.H. 분류군의 종조성 비율은 증가한 것으로 확인되었다. 서식기능군은 담수가 진행됨에 따라 붙는무리(CL; Clinger)의 종수 및 개체수 비율이 모든 지점에서 감소하였고, 굴파는무리(BU; Burrower), 기어오르는무리(CB; Climber), 기는무리(SP; Sprawler), 헤엄치는 무리(SW; Swimmer)의 종수 및 개체수 비율이 증가하였다. 또한 서식환경 변화에 따른 군집안 정성을 비교 결과, group I (높은 저항력, 높은 회복력)의 종분포는 크게 변화하지 않았으나 St.2와 St.3에서 group II(높은 저항력, 낮은 회복력)의 종 출현율이 현저히 감소하는 것으로 나타났다. 본 연구를 통해 댐 건설로 인해 담수가 진행됨에 따라 저서환경변화와 유속에 영향을 직접적으로 받는 저서성대형 무척추동물의 서식유형과 군집구조에 대한 시간적, 공간적 변화 양상을 확인할 수 있었다. 또한 향후 내성천 수계의 지속적인 모니터링을 통해 댐 건설과 이로 인한 담수의 진행 정도에 따라 저서성대형무척추동물 군집구조 변화와 서식기능군은 물론 섭식기능군의 변화 양상에 대한 체계적인 연구가 요구된다. 그리고 댐 조성이 하천생태계 저서성대형무척추동물의 분포 및 서식양태 변화에 미치는 영향에 대한 추가적인 조사 및 연구가 필요할 것으로 판단된다.