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ECI 281A Term Project Analyses of Seismic Slope Stability

ECI 281A Term Project Analyses of Seismic Slope Stability. Seoung Hyun Rho. Contents. 1. Introduction 2. Evaluation of Slope Stability 3. Static Slope Stability 3.1 Limit Equilibrium Analysis 3.2 Stress-Deformation Analysis 4. Seismic Slope Stability

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ECI 281A Term Project Analyses of Seismic Slope Stability

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  1. ECI 281A Term ProjectAnalyses of Seismic Slope Stability Seoung Hyun Rho

  2. Contents 1. Introduction 2. Evaluation of Slope Stability 3. Static Slope Stability 3.1 Limit Equilibrium Analysis 3.2 Stress-Deformation Analysis 4. Seismic Slope Stability 4.1 Analysis of inertial Instability 4.1.1 Pseudostatic Analysis 4.1.2 Newmark Sliding Block Analysis 4.2 Analysis of Weakening Instability 4.2.1 Flow Failure Analysis 4.2.2 Deformation Failure Analysis

  3. Intorduction • Landslide occurs in both natural slopes and man-made slopes. • Earthquake-induced landslides have caused great amounts of damage and loss of life throughout history. • Earthquake-induced ground shaking is one of the most frequent causes of landslides. • Thus, evaluation of seismic slope stability is one of the most important activities of the geotechnical earthquake engineer.

  4. Evaluation of slope stability • The collection of information on geological, hydrological, topographical, geometrical, and material characteristics • Field reconnaissance • Monitoring of slope movement • Subsurface investigation • Laboratory tests

  5. Static Slope stability • Slopes become unstable when the shear stress on a potential failure surface reach or exceed the shearing resistance of soil. • In the case of slopes when shear stresses on the potential failure are high, the additional earthquake-induced stresses need to trigger failure are low. • Hence the seismic stability of a slope is strongly influenced by its static stability.

  6. Limit Equilibrium Analysis • The force or moment equilibrium of a mass of soil above a potential failure surface • Assume that the soil is rigid-perfectly plastic • Thus, no information on slope deformation Stress-deformation Analysis • Performed using the finite-element method • Consideration of the stress-strain behavior of soil and rock • Offer the advantages of being able to identify the mode of failure by predicting slope deformations up to the point offailure • The accuracy of stress-deformation analyses is stronglyinfluenced by the accuracy with which the stress-strainmodel represents actual material behavior

  7. Seismic slope stability→Analysis of the seismic stability of slope is complicated by the need to consider the effects of (1) dynamic stresses induced by earthquake shaking(2) the effects of those stresses on the strength and stress-strain behavior of the slope materials 1. Analysis of Inertial instability →The shear strength of the soil remains relatively constant, but slope deformations are produced by temporary exceedances of the strength by dynamic earthquake stresses 2. Analysis of Weakening instability →occurs when the earthquake induced stresses and strains result in a substantial reduction of shear strength

  8. Pseudostatic Analysis

  9. Newmark Sliding Block Analysis(1) Figure 1. Analogy beween (a) potential landslide and (b) block resting on inclined Figure 2. Forces acting on a block resting on an inclined plane: (a) static conditions; (b) dynamic conditions.

  10. Newmark Sliding Block Analysis(2)

  11. Flow Failure Analysis • Flow failures produce large deformations and severe damage. • Developed to estimate the extent of the damage produced by flow failures • Performed in two steps 1. Analysis of Stability 2. Analysis of Deformations

  12. Deformation Failure Analysis • Hamada et al. Approach • Youd and Perkins Approach • Byrne Approach. • Baziar et al. Approach.

  13. Thank you & Any question?

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