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Numerical Analysis of Buried Pipelines Subjected to Normal-Oblique Faulting

Razavi, Omid | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41879 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofooei, Fayyaz
  7. Abstract:
  8. In existing societies, transportation of water, oil, gas and other liquids in great amounts between distant locations is economically feasible only through pipelines. Design of buried pipelines against static loads is an established and straight forward process. On the other hand, because of difficulties in predicting the behavior of buried pipelines under seismic loads and also lack of sufficient studies in this field, there is no specific code oriented approach for performance analysis of buried pipelines under seismic loads. Due to insufficient three dimensional numerical analyses on the behavior of buried pipelines crossing active normal and normal-oblique faults for different dip angles and also lack of necessary parametric studies in this field, there is a need for more precise evaluation of the problem. This study focuses on the numerical analysis of buried pipelines subjected to normal and normal-oblique faulting. In order to investigate the effect of interacting soil-pipe system, 3-D finite element analyses using shell elements for modeling the pipe and solid (brick) elements for the soil are performed. Faulting effects on the sandy soil is applied through using a static, displacement control method. Various parametric studies on the behavior of buried pipelines subjected to normal and normal-oblique faulting are conducted. The results show that tensile rupture is the major failure mode of the pipe in the case of normal and normal-oblique faulting. Furthermore it is observed that unlike steel pipes which bear tension stress in the whole length of the pipe, High Density Poly Ethylene (HDPE) pipes are subjected to compressive stress in certain parts of the pipe length. Extensive parametric studies are performed using parameters such as the pipe diameter, burial depth, diameter to thickness ratio of the pipe, soil friction angle and fault dip angle, and the results are presented in terms of axial strain and Von-Mises stress diagrams and contours for the soil and the pipe system. Considering the effect of normal-oblique faulting on buried pipelines, It is shown that (except minor differences in the failure region) the behavior and failure mode of the pipes subjected to normal and normal-oblique faults with equal fault displacement, are the same
  9. Keywords:
  10. Buried Pipline ; Permanent Ground Deformation (PGD) ; Normal Oblique Faulting ; Soil-Pipe Interaction

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