الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Despite modern advantages in technology, dam failures continue to occur.
About forty percents of earth dams failed because of overtopping and about thirty-three percents of earth dams failed because seepage through and under dam bodies.
In December 4, 1991, the left side embankment of west Nobaria drain at Zawiat Abdoul Kadder village failed.
That failure initiated this study on failures of earth dams due to overtopping and/or seepage.
In the present study new models are developed for overtopping dam failures.
The proposed models are derived depending on hydrodynamic principles (Broad crested weir) and on erosion equations.
Breach erosion is assumed as linear and nonlinear functions of the outflow mean velocity. The models are developed for rectangular, triangular and trapezoidal breach cross-sections.
The derived models are tested and compared with other models using the available data collected from previous works.
The new models results show that the nonlinear breach model for a rectangular cross-section gives more accurate results than any other model.
Also, in the present study, a computer program involving the finite element method is designed to solve the three-dimensional steady seepage through a homogeneous isotropic earth dam founded on an impervious base.
The phreatic surface is determined and then, the other seepage characteristics such as exit head, exit velocities gradients and quantity of seepage discharge are determined.
The 3-D finite element model and the design program results are verified with some exact mathematical 2-D models.
The results are presented in dimensionless form and can be used as design curves.
The effect of blockage in the dam body, due to any reason, is also studied using the same model and computer programs. The effect of blockage position and dimensions on the exit head, seepage velocity and quantity of seepage discharge is studied.
The blockage causes a significant effect on the exit velocities and the velocity gradient. The blockage in earth dams is a typical reason of dam failure and the dam materials should be designed so as to prevent any blockage.