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Numerical Modeling of Unsaturated Soils Behavior (Wheeler Model) in Flac Software

Foroughi, Sina | 2015

2011 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47015 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ahmadi, Mohammad Mehdi
  7. Abstract:
  8. The mechanical behavior of unsaturated soils is much more complex than saturated soils and the effective stress principle cannot be initially applied to them. The soils found in most parts of Tehran, Iran, are unsaturated and this underlines the importance of having access to softwares capable of analyzing such soils; despite the fact that most available softwares are unable to do so. This thesis aims at adding one of the common unsaturated soil models to a geotechnical software and use that to model and analyze earth structures such as earth dams, foundations, embankments, etc. The Wheeler model (2003) for unsaturated soils is used in this study. This model takes advantage of two independent stress variables to model a soil’s behavior. The most prominent characteristic of this model is coupling the mechanical and hydraulic behaviors of soils in addition to considering the effect of saturation on the mechanical behavior. The geotechnical software used in this study is Flac 2D which uses the Finite Difference Method (FDM) to solve the problems. In this study, the Wheeler model is first added to the software as the constitutive model of unsaturated soils, and then the results are compared to lab data and the implemented code is thus verified. Eventually, the software is used to model an embankment and an earth foundation and the results are analyzed. The comparison of the lab results and the basic BBM model results in the literature with those of this study shows that considering the coupling of the mechanical and hydraulic behavior results in a more accurate modeling and analysis. In addition, it was observed that considering the unsaturated behavior in soils results in a lower amount of settlement. In the end, the effect of climate condition on soil settlement, the most important of which is soil collapse during the wetting process, is investigated
  9. Keywords:
  10. Unsaturated Soil ; FLAC Software ; Numerical Modeling ; Wheeler Model

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