Effects of Lateral Spreading on Two 2×2 Pile Groups (with and Without Lumped Mass) Using Shaking Table and Laminar Shear Box

Zangeneh, Milad | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55384 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Haeri, Mohsen
  7. Abstract:
  8. Lateral spreading is the downstream movement of mild slopes or free fronts occurring due to soil liquefaction during a dynamic loading such as an earthquake. The magnitude of this movement can be from a few centimeters to tens of meters depending on parameters such as slope length, soil type, cyclic loading intensity, etc. Large displacements caused by this phenomenon can cause severe damage to some structures and infrastructures located in the direction of their movement. Numerous articles and reports of damage caused by the lateral spreading of soil have been presented during several earthquakes. Understanding this phenomenon and observing and testing its effective parameters can help increase the safety of designing the structures prone to this risk. The design codes of deep foundations against lateral spreading have been published before, but there are still doubts about their efficiency and accuracy. This study, which is part of a larger research project, was conducted to increase the understanding of lateral spreading and how it affects deep foundations (piles) and to investigate several primary variables in this topic using physical modeling in a laminar shear box. In this study, which is part of a large study consisting of several experiments with the participation of several doctoral and master students, two groups of 2×2 piles were installed and tested in a 3-layered soil profile. Input shaking was applied to the model using the shaking table of the Sharif University of Technology. The input loading had 30 sinusoidal cycles with a maximum acceleration amplitude of 0.3g and three initial and final cycles with lower amplitude. Strain gauges were installed on 6 piles to obtain bending moment data. Also, to better understand the soil-pile interaction, the displacement and acceleration at various depths of the soil and the pile were measured using multiple sensors. The results of this experiment were compared to the results of another study that was performed with similar loading to the present study but using a rigid box to measure the extent and effect of boundary conditions in the experiment. The use of two groups of piles, one of which had a lumped mass, made it possible to investigate the effects of a lumped mass in this phenomenon. Additionally, the results show that the position of the piles in the group is crucial and can affect the design process. Also, the effect of lumped mass on the pile groups should be considered in the design. The comparison of the results of this study with the results of the study performed using a rigid box whose liquefied layer soil had a higher relative density, showed that two factors of wave reflection in the rigid box and higher relative density can lead to an increase in the bending moment and the force applied to the piles
  9. Keywords:
  10. Liquefaction ; Lateral Spread ; Pile Group ; Shaking Table ; Soil-Pile Interaction ; Boundary Conditions ; Laminar Shear Box

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