• Title/Summary/Keyword: 3차원 사면해석

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Parametric Studies of Slope stability Analysis by 3D FEM Using Strength Reduction Method (강도감소법에 의한 3차원 사면안정해석에 대한 매개변수 연구)

  • Kim, Young-Min
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.4
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    • pp.25-32
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    • 2016
  • The two-dimensional (2D) analysis is widely used in geotechnical engineering for slope stability analysis assuming a plane-strain condition. It is implicitly assumed that the slip surface is infinitely wide, and thus three-dimensional (3D) end effects are negligible because of the infinite width of the slide mass. The majority of work on this subject suggests that the 2D factor of safety is conservative (i.e. lower than the 'true' 3D factor of safety). Recently, the 3D finite element method (FEM) became more attractive due to the progress of computational tools including the computer hardware and software. This paper presents the numerical analyses on rotational mode and translational mode slopes using the 2D and 3D FEM as well as 2D limit equilibrium methods (LEM). The results of the parametric study on the slope stability due to mesh size, dilatency angle, boundary conditions, stress history and model dimensions change are analysed. The analysis showed that the factor of safety in 3D analysis is always higher than that in the 2D analysis and the discrepancy of the slope width in W direction on the factor of safety is ignored if the roller type of W direction conditions is applied.

A Study on Shear Resistance Effect along Marginal Region of Sliding Mass using 3D Slope Stability Analysis (3차원 사면안정해석을 이용한 활동지괴 가장자리부의 전단저항에 관한 연구)

  • Seo Yong-Seok;Ohta Hidemasa;Chae Byung-Gon;Yoon Woon-Sang
    • The Journal of Engineering Geology
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    • v.14 no.4 s.41
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    • pp.451-460
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    • 2004
  • The strength of sliding plane is usually assigned on the whole sliding plane with same value in 2D limit equilibrium slope stability method. However, the potential sliding plane is divided into two or three parts which have different sliding resistances. According to the calculation results of 3D slope stability analyses using 4 types of slope cutting models, marginal sliding resistance could affect the safety of slope significantly. In this calculation two kinds of the sliding plane strengths were applied differently to the parts of bottom and margin of the model slope. The effect of marginal resistance was calculated quantitatively. In case of lower sliding resistance of the bottom, the safety factor becomes low in a margin cutting model. However, in case of higher sliding resistance of the bottom, the safety factor decreased slightly in a lower part cutting model and increased in a upper margin cutting model.

Three-dimensional Slope Stability Analysis of a Dual-lithology Slope (이종지질 분포사면에서의 3차원 사면안정해석)

  • Seo, Yong-Seok;Lee, Kyoung-Mi;Kim, Kwang-Yeom
    • The Journal of Engineering Geology
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    • v.21 no.1
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    • pp.57-64
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    • 2011
  • Three-dimensional slope stability analysis was applied to a failed dual-lithology slope containing both granite and an andesitic dyke, taking account of the differences in shear strength of the different lithologies. A direct shear test of the soil-rock boundary was performed to examine the shear strength of two different types of failure surfaces within different lithologies, and a laboratory test was performed on an upper, weathered soil layer. The test results indicate that shear strength was lower at the soil-rock boundary than within the weathered soil layer. A representative geological section was subjected to two-dimensional slope stability analysis using a limit equilibrium method to assess whether the distribution of lithologies upon the slope influences the results of stability analysis. The results were then compared with those of three-dimensional slope stability analysis, for which input parameters can be varied according to the distribution of lithologies upon the slope. The three-dimensional analysis yielded safety factors of 1.26 under dry conditions and 0.55 under wet conditions, whereas the two-dimensional analysis yielded unstable safety factors of 0.92 and 0.32, respectively. These findings show that the results of stability analysis are affected by the distribution of different lithologies upon the slope. Given that the studied slope collapsed immediately after rainfall, it is likely that the results of the three-dimensional analysis are more reliable.

3-Dimensional Analysis of Slope Behavior with Varying Safety Factor (안전계수 변화를 고려한 사면거동의 3차원 분석기법 연구)

  • Han, Heuisoo;Baek, Yong;Jo, Jaeho;Hwang, Changu
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.4
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    • pp.19-24
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    • 2010
  • Generally, slope behavior is analyzed by 2-dimensional creep model. Creep behavior shows the deformation variation as time goes by without stress increment. Convention 2-dimensional creep analysis does not have the term of stress variation, it means creep analysis could not figure out the relationship of shear strength variation according to the stress variation and displacement. The slope weight and shear strength is directly related and interlocked to the safety variation and displacement of slope, therefore, this phenomenon could be treated and analyzed as combining the hysteresis and creep, the iteration of this process will result in the slope safety. Furthermore, the combined analysis will be the slope analysis considering shear stress, displacement and shear strength with time variation. In real case, because the variation of shear stress and strength happen at the same time, they should be changed into safety factor which is function of them. This paper shows the 3-dimensional variation of unit weight of soil with hybrid analysis considering creep and hysteresis on the seepage and drainage of rainfall, futhermore variations of shear stress and strength which make the safety factor change.

Rockfall and Toppling Failure Simulation of Rock Slopes using 3-Dimensional Discontinuous Deformation Analysis (3차원 불연속변형해석법을 이용한 암반사면의 낙석과 전도 파괴 시뮬레이션)

  • Hwang, Jae-Yun;Ohnishi, Yuzo
    • Tunnel and Underground Space
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    • v.22 no.3
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    • pp.181-187
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    • 2012
  • Many researches on disaster prevention using computer simulation methods can be performed to minimize the damage of property and to protect human life. Discontinuous deformation analysis (DDA) is a new computer simulation method to analyze the behavior of discontinuous rock masses. Since most rock slope problems are 3-dimensional in nature, 2-dimensional deformation analysis has limited application. In this study, the basic principles of 3-dimensional discontinuous deformation analysis are described. The newly developed 3-dimensional discontinuous deformation analysis method is proposed as the computer simulation method for discontinuous rock masses. Then, the failure behavior of rock slopes are simulated using 3-dimensional discontinuous deformation analysis. The simulation results are compared and examined with the failure behavior at the rock slopes. The results show the applicability of 3-dimensional discontinuous deformation analysis to analyze the deformation and failure mechanisms of rock slopes.

A Short Note on 3-Dimensional Slope Stability Analysis (3차원 사면안정해석에 관한 소고)

  • 서용석;윤운상
    • The Journal of Engineering Geology
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    • v.14 no.2
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    • pp.235-241
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    • 2004
  • 사면활동은 삼차원적인 토괴 혹은 암괴의 입체적 움직임의 산물이며 여러 가지 복잡한 지질학적 요인에 의하여 발생하고 있다. 하지만 사면안정해석은 일반적으로 이차원적으로 수행됨으로써 해석모델을 극히 단순화시키고 있다.(중략)

Three-dimensional Finite Element Studies of the Behavior of Short Pile Subjected to Lateral Load near a Sandy Slope (모래사면에 설치된 수평하중을 받는 짧은 말뚝의 거동에 관한 3차원 탄소성 유한요소해석)

  • ;Ugai Keizo;Wakai Akihiko
    • Journal of the Korean Geotechnical Society
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    • v.17 no.3
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    • pp.41-50
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    • 2001
  • 본 연구는 모래사면의 언덕근처에 설치된 짧은 말뚝의 수평하중의 영향에 관한 것이다. 3차원 탄소성 유한요소법해석과 실내 모형실험의 결과를 비교하였다. 경사 30$^{\circ}$의 사면에 시공된 짧은 말뚝의 특성을 파악하기 위해, 사면언덕에서 모형말뚝까지의 거리를 3종류로 상이하게 하여, 모형실험을 실시하였다. 사용된 모래의 지반특성은 배수조건하의 삼축압축실험으로 결정하였다. 동시에 3차원 탄소성 유한요소법에 의한 수치해석결과와 모형실험결과를 비교하였다. 본 유한요소법의 해석에 있어서 모래지반을 탄성완전소성모델(Elastic-perfectly plastic model)로 가정하여, 파괴기준으로 Mohr-Coulomb 식과 소성 포텐셜에 대해서는 Drucker-Prager 식을 적용한 MC-DP 모델로 하였다. 이러한 MC-DP 모델의 구성식은 유한요소법에서 있어 계산치의 수렴에 유익하다. 3차원 탄소성 유한요소법에 의한 수치해석이 사질토 사면의 언덕 부근에 설치된 단하의 수평거동에 대한 파악에 유효하다는 것을 확인하였다.

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Analysis of Talus Slope Stability using 2D FEM and 3D Limit Equilibrium Method (2차원 유한요소법과 3차원 한계평형법을 이용한 테일러스 사면안정성 해석)

  • Lee, Kyoung-Mi;Kim, Sung-Kwon;Seo, Yaung-Seok;Lee, Sun-Bok;Kim, Dong-Hyun;Kim, Do-Sik
    • The Journal of Engineering Geology
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    • v.17 no.3
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    • pp.381-391
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    • 2007
  • A series of talus slope stability analyses were carried out using 2D FEM and 3D limit equilibrium methods for this study. The FEM analyses on Phase 2 were performed to delineate failure depths based on stress distributions for each slope. The results revealed that the failure surface exist in the colluvium layer of about 3-10 m thickness. Three dimensional models, derived from the FEM analyses and geological field survey, were made for the use in a 3D limit equilibrium analysis. The result shows that all the talus slopes are stable under dry condition, but unstable under saturated condition due to heavy rain.

A Study on the Factor of Safety for Rock Slopes Based on Three Dimensional Effects (3차원 효과를 고려한 암반사면의 안전율 변화에 관한 연구)

  • Seo, Og-Geon;Lee, Seung-Ho
    • Journal of the Korean Geotechnical Society
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    • v.31 no.1
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    • pp.47-52
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    • 2015
  • In the slope stability analysis and design, Limit Equilibrium Method (LEM) and Shear Strength Reduction technique (SSR) are mainly used. Both methods are able to perform two and three dimensional analysis. SSR is considered to be more sensitive and more reasonable than LEM by many researchers. However, in practice LEM is still widely used because of the increase of analysis time and complexity of the model in SSR. In this study, three dimensional analysis of the protruding rock slope is performed by SSR in order to study the effects of protruding length using rock slope FLAC 3D. In this study, as results of analysis variations of the safety factor have been studied according to slope angle, slope height, the soil strength, protruding slope length projected variables. The results show that the factor of safety as more affected by the shapes of the protruding rock slope than the rock strength.

A Reliability Analysis of Slope Stability of Earth-Rockfill Dam (Earth-Rockfill Dam사면파괴에 대한 신뢰도 연구(I))

  • 박현종;이인모
    • Geotechnical Engineering
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    • v.7 no.3
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    • pp.21-32
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    • 1991
  • The purpose of this paper is to develop a reliability model for slope stability of Earth-rockfill dams which accounts for all uncertainties encountered. The uncertain factors of the design variables include the cohesion, the angle of internal friction, and the porewater Pressure in each zone. More specifically, the model errors in estimating those variables are studied in depth. To reduce the uncertainties due to model errors, updated design variables are obtained using Bayesian Theory. For stability analysis, both the two-dimesional stability analysis and the three-dimensional stability analysis where the end effects and the system reliability concept are considered are used for the reliability calculations. The deterministic safety factor by the three-dimensional analysis is lager than that by the two-dimensional anlysis. However, the probability of failure by the three-dimensional analysis is about 3.5 times larger that by the two-dimensional analysis. It is because the system reliability concept is used in the three-dimensional analysis. The sensitivity analysis shows that the probability of failure is more sensitive to the uncertainty of the cohesion than that of the angle of internal friction.

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