Parametric Study of Shallow Foundations Settlement Due to Liquefaction Phenomenon on a Two-Layered Soil

Ayoubi, Peyman | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46658 (09)
  4. University: Sharif University Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. Settlement and tilt of structures due to liquefaction of subsoil layers is a major cause of damage during earthquake. Among different soil profile type, two layered soil is very common which was reported many times in differen earthquakes. Settlement of structures was measured by means of empirical methods before which were not viable because they do not consider different effective parameters. Consequently, different experimental studies performed to shed light on different aspects of liquefaction phenomena. In these studies, researchers consider some of the main parameters which have effect on the soil, otherwise, they neglected some important factors. So, numerical procedure is more attractive for researchers to take into account wide variety of parameters. Because of lack of numerical procedures by which settlement of structure could be measured, the numerical study presented in this research, addresses the effects of different parameters which have effect on liquefaction in saturated sand deposits underlying foundation of structures. In this regard, a 3D finite element model for fully coupled dynamic analysis of saturated porous media has been utilized. For constitutive modeling of sand behavior, a well-calibrated bounding-surface plasticity model which is capable of accounting for the monotonic and cyclic response of saturated sand in a wide range of densities and confining pressures, has been used. Another main feature of the proposed numerical model is the taking of the variation of permeability into account during liquefaction. The numerical simulations of this study have been performed using OpenSees which is an open-source software framework. In this research, two 3D u-p elements with novel variable Petmeability functions have been used which was implemented by others in OpenSees.
    The numerical model has been verified by simulation of a series of centrifuge experiments performed on models of footing on liquefiable and the analysis results are compared with the experimental measurements. After verification of the numerical model, comprehensive parametric studies have been conducted and based on the obtained results effects of parameters were reported
  9. Keywords:
  10. Liquefaction ; Numerical Modeling ; Parametric Study ; Settlement ; Two-Layered Soil

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