The Formation Mechanism And Numerical Simulation Of Piping Central Seepage Flow Channel In Embankment

With the rapid development of the hydro-electric industry, a lot of hydro-electric projects are built, the earth rock dam and embankment projects hold the main proportion, and the seepage deformation and the seepage failure of the levee construction are one of the key researches, especially the piping research. In the process of levee seepage, the problem of the small grain migration is often occurred. For the layer of small grain, the process of seepage is equal to seep-out of muddle water, so the piping problem is the most typical problem of muddle water seep, but all of the methods used in the solving the muddle water seep are based on the theory of the rinsing seep which ignores the effect of the sand and mud migration, this do not completely match with the fact so that the result has great windage. Based on the essential of the piping problem is the same as the muddle water problem ,the piping phenomenon of the levee dam is researched by researching the process of seep-out of muddle water.In this paper, according to the seep-out of muddle water which is a representative problem, we have a new idea to solve the problem. We now consider that bed load which is taken way by seepage in the process of muddle water seep courses the changes of pervasion coefficient and porosity coefficient. At the same time the increase of pervasion coefficient and porosity coefficient has also strengthened the ability of carrying away bed load of muddle water seep. This is an inter-action and stimulative process. According to this idea, we have based on Darcy law, cited with current flow stream taking sand ability classical expressions and used mathematical method deducing a theoretic expression of the seep-out of muddle water, giving difference of the seep-out of muddle water differential equation. We have also used FORTRAN to calculate the process of the seep-out of muddle water with definite volume and we can also get disciplinarian curve of pervasion coefficient, porosity coefficient and quantity of seepage.In this paper, based on the deep analysis of mechanism of seepage channels when dams occurs piping, we used Geo-Studio to calculate the influencing area of piping beginning and used program of the seep-out of muddle water to calculate the process of osmotic damage in the piping influencing area, so that to get the curve of pervasion coefficient, porosity coefficient and quantity of seepage, then get the results back to Geo-Studio in order to carry throughiterative calculation. According to this method, we can simulate the forming process of piping concentrating in the seepage channels, calculate the direction of piping concentrating in the seepage channels in order to provide some reference to rush to repair and pin up the dyke.