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Master thesis at University of Technological discusses the behavior of water tanks during sudden filling and sudden discharge of soil dams

Master thesis at University of Technological discusses the behavior of water tanks during sudden filling and sudden discharge of soil dams

A graduated student Mohammed Aaed Hassan obtained master's degree in water resources engineering from the department of construction and building engineering / university of Technology with the degree very good for his thesis entitled:
"The behavior of water tanks during sudden filling and sudden discharge of soil dams
in the discussion that was held at the Hall of the deceased Prof Dr. Nema Hamad Aumara.
The discussion committee consisted of professors: Assistant Prof. Dr. Jafar Sadiq Matouk from the Department of Building and Construction Engineering at the University of Technology (as apresident) and Assistant Prof. Dr. Thaer Jabbar Mezher from the Faculty of Engineering at the University of Babylon, Assistant Prof. Dr. Falah Hassan Raheel(as members) ,Assistant Prof. Dr. Mohamed Yousif Fatah and Assistant Prof. Hassan Ali Omran, from the Department of Building and Construction Engineering at the University of Technology(as supervisors).
This study use the method of specified elements to study the leakage through the soil dam body. So Geostudio program 2007 was used in its two branches W / SEEP and W / SLOPE. The water levels on both sides of the tank , downstream, the material properties and the specific conditions of the dam are the variable inputs, while the amount of water exuding and gradient exist and pore water pressure are the required outputs of the program. The output results were compared W/SEEP with calculated data. It has been verified from the program by the way of analyzing two models that have been previously analyzed using the method of (flow net).
Eight nodes elements were used to analyze the dam and its foundations, while an infinite elements have been used to specify the limited conditions of the studied case.
In this study, An analysis was made for many heterogeneous soil dams and analysis of each case in several periods of emptying the tank, included Al-Wand Dam, Mandawa Dam, Al-Ethaem Dam. Accurate results were found by the use of Mandawa Dam and AL-Ethaem Dam in that it was found that the best case was made during the original discharge period of the tank. It was concluded that when the tank was emptying rapidly, the pore pressure of water in the body of the dam was declining for two reasons:
First, there is the slow dissipation of pore water pressure due to the discharge.
Second, there is a flexible immediate effect due to the removal of water pressure.
During the sudden fall in the level of the tank, the pore water pressure at all points within the body of the dam is lowered linearly which prove that the steady-state appeared in clear picture through this down. Some points in the body of the dam in the background area of the dam may be affected because of the negative pore water pressure during the descent of water, which shows that the water level becomes less than these points.
The (exit gradient) in the back of the dam was decreased during the descent of water, which means that the safety factor against seepage will increase with the passage of time. When the emptying period of the tanks was long(about 10 days), the value of (exit gradient) will become higher than the previous one.
The flow rate in the back of the dam will increase with time, this increase occurred because of the rapid flow of water caused by emptying the tank in a short period. Overall water flow decreases linearly with time and with the water level in the tank which shows that the flow rate in the body of the dam appears regularly .
The factor of safety against sliding of the dam slopes decreased little in short period of time after the start of the sudden drop in the water tank, then begins to increase. This occurs because the pore water pressure dissipation after the start of discharge which leads to increase the effective pressure in the soil, thereby increasing the shear power inside the soil. Saturated slope of weight produces shearing stresses while shear strength significantly reduced due to the growth of pore water pressure that does not dissipate rapidly .


Source: Uot Media

Date :05/01/2015