Numerical Simulation of Effect of Lateral Spreading Due to Liquefaction on Piles and Estimate Soil Lateral Displacement Pattern by Image Processing

Sayaf, Hiva | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50593 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Haeri, Mohsen
  7. Abstract:
  8. In recent earthquakes piles have been severely damaged due to liquefaction-induced lateral spreading. Liquefaction causes lateral spreading in gently sloped saturated soft granular soils, leading to significant damage in structures and deep foundations. Although in recent years many studies have focused on different aspects of this phenomenon, the complex nature of the dynamic interaction between piles and liquefied soil is not yet fully understood. This potential damages are of high degree of importance in southern and northern coastal areas of Iran where several ports and critical facilities are located. The present study focuses on the behavior of a 2x2 pile group against lateral loads due to lateral spreading with numerical methods using OpenSees software. Laboratory tests of the effect of lateral spreading on pile groups using shake table have been performed at Sharif University of Technology during 2010-11 in a rigid box with dimensions of 3.5m x 1m x 1.5m. The laboratory test used for verification of the numerical model of this study is the test done on 2x2 pile group tested under a sinusoidal motion with a maximum acceleration of 0.3g Soil layers in that experiment included a liquefiable layer with a thickness of 1m which was located between two non-liquefiable layers, an upper layer with a thickness of 25cm and a lower layer with a maximum thickness of 25cm. The inclination of discribed layers was 4o. The numerical model of this research was first verified with the described physical model and then a parametric study in prototype dimensions was performed. Comaprison of the results from numerical model with that of physical model showed that predictions of excess pore water pressure and bending moment of piles using numerical method are acceptable. Parametric studies include the effects of inclination of discribed layers and piles diameter and the effect of pile module and condition of pile cap (fixed/free) on the response of 2x2 pile group to lateral spreading. Increasing liquefiable layer angle increases the maximum displacement of the soil profile and bending moment of the piles. Also reducing pile stiffness causes reduction in bending moment of the piles. The image processing used for estimate of soil lateral displacement. According to the images from physical modeling Kavand et al. (2013) few relations obtained for estimate soil lateral displacement, as the result of that maximum displacement of surface achived
  9. Keywords:
  10. Image Processing ; OpenSees Software ; Numerical Modeling ; Pile Group ; Liquefaction ; Liquefaction-Induced Lateral Spreading

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