Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

The safety of buried pipelines during earthquakes has involved a great deal of attention in last few years. Important characteristics of buried pipelines are that they cover large areas and can be subjected to a variety of geotectonic hazards. Earthquake damages to buried pipelines can be attributed to transient ground deformations (TGD), permanent ground deformations (PGD) or both. PGD occurs as a result of surface faulting, liquefaction, landslides, and differential settlement from consolidation of cohesionless soil. To evaluate seismic behavior of buried pipelines subjected to large values of permanent ground deformations, appropriate non-linear cyclic stress-strain relationship should be implemented in any numerical method. Among the phenomena, which cause permanent ground deformations, the settlement and lateral spreading induced by liquefaction are considered as the main cause of damage in buried structures. Therefore, this study is aimed to take into account the potential of liquefaction during an earthquake into the numerical analysis of buried pipelines using FEM. During the earthquake, the soil volume and also pore-pressure water is changed and therefore as saturated loose sands undergo simple shear deformations, the stiffness at any time is changed as the function of mean normal effective stress. In this study, a hypo-elastic model is adopted for the soil to evaluate changes in the pore pressures and also effective stresses during the excitation. In a finite element modeling, for the areas not expecting the liquefaction to occur, the pipe is modeled using beam elements and soil is modeled by some bi-linear springs; while for liquefied areas, the pipe is modeled by shell elements and solid elements are used to model the surrounding soil.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

Share

 
COinS
 
Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Nonlinear Seismic Analysis of Buried Pipelines During Liquefaction

Arlington, Virginia

The safety of buried pipelines during earthquakes has involved a great deal of attention in last few years. Important characteristics of buried pipelines are that they cover large areas and can be subjected to a variety of geotectonic hazards. Earthquake damages to buried pipelines can be attributed to transient ground deformations (TGD), permanent ground deformations (PGD) or both. PGD occurs as a result of surface faulting, liquefaction, landslides, and differential settlement from consolidation of cohesionless soil. To evaluate seismic behavior of buried pipelines subjected to large values of permanent ground deformations, appropriate non-linear cyclic stress-strain relationship should be implemented in any numerical method. Among the phenomena, which cause permanent ground deformations, the settlement and lateral spreading induced by liquefaction are considered as the main cause of damage in buried structures. Therefore, this study is aimed to take into account the potential of liquefaction during an earthquake into the numerical analysis of buried pipelines using FEM. During the earthquake, the soil volume and also pore-pressure water is changed and therefore as saturated loose sands undergo simple shear deformations, the stiffness at any time is changed as the function of mean normal effective stress. In this study, a hypo-elastic model is adopted for the soil to evaluate changes in the pore pressures and also effective stresses during the excitation. In a finite element modeling, for the areas not expecting the liquefaction to occur, the pipe is modeled using beam elements and soil is modeled by some bi-linear springs; while for liquefied areas, the pipe is modeled by shell elements and solid elements are used to model the surrounding soil.