Analysis On Isotropic Earth Dam Of Unsteady Seepage When The Reservoir Water Falling

Earth dam is one of the most important constructions of the reservoir pivot and its function is to impound flood water. Earth dam has the advantages of lower requirement to terrain conditions and less cost, as the result, it receives wide applications. The security of earth dams is always the hot top and the serious seepage is the most important influence factor in all factors resulting in the earth dam destruction. In this paper, the change of the hydraulic grade line in the dam is studied based on the basic theory of seepage. The following is included:1. Explaining the basic concept and deducting the basic equation of seepage based on the soil-water motion equation. Further, clarify the concept of steady-unsteady seepage and its initial and boundary conditions. Also, differential equation of steady-unsteady seepage had deducted.2. Expatiating the solution methods of the seepage and stress on the numerical solution, furthermore, the theory and methods and solution process of finite element is particularly studied. The finite element format of differential equation is deduced based on Galerkin method of weighted residual.3. The classical counting model is compared with measured value to verify the feasibility of UNSST2 program which base on the theory of finite element. Further, the seepage field of engineering case Sang jian reservoir dam of Ding yuan county An hui province is calculated applied of this program.4. Analyzing the change of the hydraulic grade line in the dam in different conditions when the water level falling. Also, the experience formula is obtained about the highest point of the hydraulic grade line. In this paper, the change of the hydraulic grade line in the earth dam and the gradient ratio are discussed when the water level falling, which offer feasible and appropriate references for the design and run and administer of reservoir.