Loading...

Numerical modeling of The Deformation of Rockfill Dams (Case Study: Masjed-soleyman Dam)

Baratinia, Amir | 2019

385 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51746 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. Rockfill dams are a kind of gravity dams that a major part of the dam’s body is made of rock particles. The specific feature of these dams is the high settlement of rockfill layers so, numerical simulation of the behavior of these dams for predicting their settlement is of prime importance. However, the normal procedure of numerical modeling and the analysis of stresses and deformations using common engineering softwares usually does not work because the behavior of rockfills is not well understood. Evaluating the mechanical behavior of rockfill layers is not usually possible in the laboratory because of the large dimensions of these particles which are sometimes larger than one meter. Therefore, laboratory studies require special devices of very large scale. For this reason, explaining the complicated behavior of rockfills, its numerical modeling, and prediction of rockfill dams’ behavior is one of the challenges of geotechnical engineers. In the current research, Masjed-Soleiman dam, one of the highest embankment dams in Iran that has experienced significant settlement during construction and reservoir infilling, is studied. In this study, FLAC software and Strain-Hardening/Softening constitutive model (SS) are used. To achieve appropriate parameters for the chosen constitutive model, large scale triaxial tests carried out on the dam’s rockfill materials at the University of Karlsruhe in Germany were modeled. In this regard, the equation proposed by Rowe is modified to bring numerical modeling results closer to the experimental results as much as possible. However, it was observed that, despite the use of appropriate constitutive model and precise parameters, the deformations predicted by numerical modeling, especially in the dam’s downstream shell had a significant difference comparing to the recordings carried out by the instrumentation installed in the dam body. By investigating the results of the instrumentation of the dam along with the study of the history of atmospheric precipitations in this area, it was observed that the collapse settlement was owing to high rainfalls in the area and this has been the cause of the large deformations of the Masjed-Soleiman Dam’s downstream shell. The result showed that the rockfill layer of the dam body is affected not only by inundation but also by the humidity change. Therefore, using the proposed Jasto method, the rockfill collapse settlement was introduced into the FLAC model. By this, numerical modeling results were significantly improved and came close to the measured values. The present study showed that rockfill layer behavior and its large deformation follow the changes of rockfill humidity. Therefore, in addition to the collapse settlement of rockfill layer which occurs in dam’s upstream shell during inundation, it is also necessary that collapse settlement of dam’s downstream shell because of the change in humidity due to atmospheric precipitations is modeled using the correct parameters and more advanced constitutive models that can take collapse settlement into account. The other conclusion is that during the construction of rockfill dams, the more the moisture is used while compacting the rockfill shell, the less the settlement will occur after construction
  9. Keywords:
  10. Numerical Modeling ; Rockfill Dam ; Collapse Settlement ; Saturation ; Humidity Change

 Digital Object List

 Bookmark

No TOC