Numerical model for seepage flow under floor of irrigation structures

A Finite element study of seepage flow under floor of hydraulicstructure floor with cracks and cracked sheet piles was conducted usingfour-node quadrilateral isoparametric element. An experimental workwas performed using Sand Model Tank. A dimensional analysis wasdone to obtain the dimensionless parameters affecting the seepage flowcharacteristics. Single sheet pile, double sheet piles, single crack anddouble cracks were studied. The effect of the depth of impermeablelayer, relative depths of sheet pile(s), the position of crack(s) in sheetpile(s) and in the floor were presented using dimensionless graphs.Application of the seepage model, using finite element method, wasintroduced on the floor of Esna Barrages using four-node quadrilateralisoparametric element. The effect of possible cracks in the floor and insheet piles were studied and the factor of safety in the uplift pressuresand exit gradients were obtained. It was found that the maximumreduction in the relative uplift pressure occurred due to an increase in therelative depth of crack which ranged from 0.2 to 0.4 measured fromfloor. The presence of sheet pile wall causes a significant reduction inthe relative uplift pressures and the presence of cracks in the sheet pileincreased the relative uplift pressure under the floor part downstream thesheet pile. The increase in the relative crack depth in the sheet pilemeasured from the floor caused an increase in the relative upliftpressures under the floor upstream the sheet pile. But for the floordownstream the sheet pile, the relative uplift pressures was decreased forthe increase in the relative depth of crack.