• Title/Summary/Keyword: Seismic slope stability

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Estimation of amplification of slope via 1-D site response analysis (1차원 지반응답해석을 통한 사면의 증폭특성 규명)

  • Yun, Se-Ung;Park, Du-Hee
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.620-625
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    • 2009
  • The seismic slope stability is most often evaluated by the pseudo-static limit analysis, in which the earthquake loading is simplified as static inertial loads acting in horizontal and/or vertical directions. The transient loading is represented by constant acceleration via the pseudostatic coefficients. The result of a pseudostatic analysis is governed by the selection of the value of the pseudostatic coefficient. However, selection of the value is very difficult and often done in an ad hoc manner without a sound physical reasoning. In addition, the maximum acceleration is commonly estimated from the design guideline, which cannot accurately estimate the dynamic response of a slope. There is a need to perform a 2D dynamic analysis to properly define the dynamic response characteristics. This paper develops the modified one-dimensional seismic site response analysis. The modified site response analysis adjusts the density of the layers to simulate the change in mass and weight of the layers of the slope with depth. Multiple analyses are performed at various locations within the slope to estimate the change in seismic response of the slope. The calculated peak acceleration profiles with depth from the developed procedure are compared to those by the two-dimensional analyses. Comparisons show that the two methods result in remarkable match.

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Development of Novel Method of Seismic Slope Stability Analysis (신(新) 유사정적 사면안정해석 기법 개발)

  • Yun, Seung;Park, Duhee;Lee, Seungho;Hwang, Youngchul
    • Journal of the Korean GEO-environmental Society
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    • v.10 no.1
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    • pp.49-54
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    • 2009
  • The seismic slope stability is most often evaluated by the pseudo-static limit analysis, in which the earthquake loading is simplified as static inertial loads acting in horizontal and/or vertical directions. The transient loading is represented by constant acceleration via the pseudostatic coefficients. The result of a pseudostatic analysis is governed by the selection of the value of the pseudostatic coefficient. However, selection of the value is very difficult and often done in an ad hoc manner without a sound physical reasoning. In addition, the maximum acceleration is commonly estimated from the design guideline, which cannot accurately estimate the dynamic response of a slope. There is a need to perform a 2D dynamic analysis to properly define the dynamic response characteristics. This paper develops a new hybrid pseudostatic method that links the modified one-dimensional seismic site response analysis and the pseudostatic algorithm. The modified site response analysis adjusts the density of the layers to simulate the change in mass and weight of the layers of the slope with depth. Multiple analyses were performed at various locations within the slope to estimate the change in seismic response of the slope. The calculated peak acceleration profiles with depth from the developed procedure were compared to those by the two-dimensional analyses. Comparisons show that the two methods result in remarkable match. The calculated profiles are used to perform pseudostatic analysis. The results show that use of peak or a fraction of acceleration at the surface can seriously underestimate or overestimate the factor of safety, and that the proposed procedure significantly enhances the reliability of a standard procedure.

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Simulation-Based Assessment of Seismic Slope Stability (시뮬레이션 기법을 이용한 지진 시 사면안정 해석)

  • 김진만
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2003.03a
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    • pp.157-164
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    • 2003
  • A simulation-based approach that can be used to systematically model the uncertainties of seismic loading and geotechnical property is presented in the context of reliability analysis of slope stability. The uncertainty of seismic loading is studied by generating a large series of hazard-compatible artificial motions, and by using them in subsequent response analyses. The stochastic nature of spatially varying material properties and also the uncertainty arising from insufficient information are treated in the framework of random fields. The simulation-based analyses indicate that in a seismically less active region, a moderate variability in soil properties has a relatively large effect as much as characterization of earthquake hazard on the computed risk of slope failure and excessive slope deformations.

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Investigation of Effect of Input Ground Motion on the Failure Surface of Mountain Slopes

  • Khalid, Muhammad Irslan;Pervaiz, Usman;Park, Duhee
    • Journal of the Korean GEO-environmental Society
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    • v.22 no.7
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    • pp.5-12
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    • 2021
  • The reliable seismic stability evaluation of the natural slopes and geotechnical structures has become a critical factor of the design. Pseudo-static or permanent displacement methods are typically employed to evaluate the seismic slope performance. In both methods, the effect of input ground motion on the sliding surface is ignored, and failure surface from the limit equilibrium method is used. For the assessment of the seismic sensitivity of failure surface, two-dimensional non-linear finite element analyses are performed. The performance of the finite element model was validated against centrifuge measurements. A parametric study with a range of input ground motion was performed, and numerical results were used to assess the influence of ground motion characteristics on the sliding surface. Based on the results, it is demonstrated that the characteristics of input ground motion have a significant influence on the location of the seismically induce failure surface. In addition to dynamic analysis, pseudo-static analyses were performed to evaluate the discrepancy. It is observed that sliding surfaces developed from pseudo-static and dynamic analyses are different. The location of the failure surface change with the amplitude and Tm of motion. Therefore, it is recommended to determine failure surfaces from dynamic analysis

Reliability Analysis of Seismically Induced Slope Deformations (신뢰성 기법을 이용한 지진으로 인한 사면 변위해석)

  • Kim, Jin-Man
    • Journal of the Korean Geotechnical Society
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    • v.23 no.3
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    • pp.111-121
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    • 2007
  • The paper presents a reliability-based method that can capture the impact of uncertainty of seismic loadings. The proposed method incorporates probabilistic concepts into the classical limit equilibrium and the Newmark-type deformation techniques. The risk of damage is then computed by Monte Carlo simulation. Random process and RMS hazard method are introduced to produce seismic motions and also to use them in the seismic slope analyses. The geotechnical variability and sampling errors are also considered. The results of reliability analyses indicate that in a highly seismically active region, characterization of earthquake hazard is the more critical factor, and characterization of soil properties has a relatively small effect on the computed risk of slope failure and excessive slope deformations. The results can be applicable to both circular and non-circular slip surface failure modes.

Review of earthquake-induced landslide modeling and scenario-based application

  • Lee, Giha;An, Hyunuk;Yeon, Minho;Seo, Jun Pyo;Lee, Chang Woo
    • Korean Journal of Agricultural Science
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    • v.47 no.4
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    • pp.963-978
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    • 2020
  • Earthquakes can induce a large number of landslides and cause very serious property damage and human casualties. There are two issues in study on earthquake-induced landslides: (1) slope stability analysis under seismic loading and (2) debris flow run-out analysis. This study aims to review technical studies related to the development and application of earthquake-induced landslide models (seismic slope stability analysis). Moreover, a pilot application of a physics-based slope stability model to Mt. Umyeon, in Seoul, with several earthquake scenarios was conducted to test regional scale seismic landslide mapping. The earthquake-induced landslide simulation model can be categorized into 1) Pseudo-static model, 2) Newmark's dynamic displacement model and 3) stress-strain model. The Pseudo-static model is preferred for producing seismic landslide hazard maps because it is impossible to verify the dynamic model-based simulation results due to lack of earthquake-induced landslide inventory in Korea. Earthquake scenario-based simulation results show that given dry conditions, unstable slopes begin to occur in parts of upper areas due to the 50-year earthquake magnitude; most of the study area becomes unstable when the earthquake frequency is 200 years. On the other hand, when the soil is in a wet state due to heavy rainfall, many areas are unstable even if no earthquake occurs, and when rainfall and 50-year earthquakes occur simultaneously, most areas appear unstable, as in simulation results based on 100-year earthquakes in dry condition.

A Study on the Estimation of Slope Stability under the Influence of the Vertical Direction Seismic Coefficient Using Lower Bound Analysis (하계해석을 이용한 수직방향 지진계수 영향에 따른 비탈면의 안정성 평가 연구)

  • Choi, Sang-Ho;Kim, Jong-Min;Kim, Yong-Soo
    • Journal of the Korean Geotechnical Society
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    • v.28 no.12
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    • pp.123-131
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    • 2012
  • Recent earthquake records indicate that the vertical component of earthquake loading, generally neglected in seismic slope stability analysis, has a significant influence on the stability. This is particularly true for the earthquakes originating inside the continent, not from its boundaries. Therefore the design of geotechnical structures without consideration of vertical component of earthquake loading may result in unsafe design. In this study, with a consideration of the effect of vertical seismic loading, the horizontal yield seismic coefficients under various slope conditions are estimated, using the lower bound limit analysis. In addition, the equation for the determination of the critical direction (either upward or downward) of vertical seismic loading is proposed.

Earthquake Resistant Design Methods on the Slopes (지진을 고려한 비탈면 설계 방안)

  • Kim, Ju-Hyong;Lee, Yong-Su;Cho, Sam-Deok
    • Journal of the Korean Society of Hazard Mitigation
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    • v.5 no.1 s.16
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    • pp.23-32
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    • 2005
  • A significant development has been made on earthquake resistant designs on many structures since the Korean government has begun modern earthquake hazard reduction programs after recognizing potential disastrous consequences of seismic events following the Kobe earthquake in 1995. However, some structures such as slope structures still haven't get ready for their own seismic design guidelines in Korea. Therefore, only a few organizations of Korea adopt seismic design for slopes relying on designers' judgments at present. This paper introduces domestic and foreign research activities on seismic slope stability and an idea of Korean earthquake resistant design method for slopes including alternatives of earthquake resistant design application according to designers' judgment considering construction budget, importance, restoration and so on. Afterwards, seismic data accumulation on slope stability of Korea is necessary to induce a more definite Korean earthquake resistant design method.

Development of Permanent Displacement Model for Seismic Mountain Slope (지진 시 산사면의 영구변위 추정식 개발)

  • Lee, Jong-Hoo;Park, Duhee;Ahn, Jae-Kwang;Park, Inn-Joon
    • Journal of the Korean Geotechnical Society
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    • v.31 no.4
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    • pp.57-66
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    • 2015
  • Empirical seismic displacement equations based on the Newmark sliding block method are widely used to develop seismic landslide hazard map. Most proposed equations have been developed for embankments and landfills, and do not consider the dynamic response of sliding block. Therefore, they cannot be applied to Korean mountain slopes composed of thin, uniform soil-layer underlain by an inclined bedrock parallel to the slope. In this paper, a series of two-dimensional dynamic nonlinear finite difference analyses were performed to estimate the permanent seismic slope displacement. The seismic displacement of mountain slopes was calculated using the Newmark method and the equivalent acceleration time history. The calculated seismic displacements of the mountain slopes were compared to a widely used empirical displacement model. We show that the displacement prediction is significantly enhanced if the slope is modeled as a flexible sliding mass and the amplification characteristics are accounted for. Regression equation, which uses PGA, PGV, Arias intensity of the ground motion and the fundamental period of soil layer, is shown to provide a reliable estimate of the sliding displacement. Furthermore, the empirical equation is shown to reliably predict the hazard category.