NUMERICAL SIMULATION OF TWO DIMENSIONAL UNSTEADY STATE SEEPAGE THROUGH EARTH DAMS

Abstract

Earthen dams are widely utilized as water retention structures. In many cases they are the only feasible and reliable structures that are possible at sites where the foundations are relatively weak. However, significant problems as seepage through the foundation and through the earthen dam itself are of serious consideration. The steady state, saturated seepage has been widely studied and discussed among research scientists. But more complex and accurate approaches have been taken on recent times. The study of unsteady state, unsaturated seepage is becoming more popular with the help of modern computers and better instrumentation. Still, up to date, they are unknowns and limited researches done on several aspects influenced by an unsteady state, unsaturated seepage, as the built up of uplift pressure with time at the base of the dam. One of the purposes of this dissertation is to estimate the relationship of uplift pressure built up with time. Is the hope of the author that this effort will contribute to better understanding of this phenomena and will give as basis on further studies on control of seepage below and through earth darns, design of impervious blankets, and serviceable design of earthen dam structures. (iv) The need for understanding the unsteady state, unsaturated seepage through earthen dams is discussed on the Introduction on Chapter one, the Present Work• is reviewed to explain the progress, achieved on this subject. This is followed up by discussion of the different numerical and analytical methods. used. On Chapter two, the formulation of the unsteady state, unsaturated seepage differential equation is explained. This equation will be numerically solved and applied on the body of this study. On Chapter three, the method of finite differences is discussed in details and its application to solve the governing differential equation is given. Details on unsaturated flow conditions, limitations and assumptions are also discussed. On Chapter four, the numerical algorithm, that was applied, is described. The flow chart of the application program is detailed and examined. Flow charts are provide( the utilized variables are also discussed. On Chapter five, the computer Coding in FORTRAN is presented. the logic and linkage of different specific subroutines is discussed. The coded variables are also listed and explained. (v) On Chapter six the computer listing, examples of data files preparation, running of the Program and other details are explained. On Chapter seven, the Results of selected analysis are discussed and observations are prepared. Finally, we intent to draw some conclusions and achievements of this study.