3D seepage under hydraulic structures provided with intermediate filters

Abstract

Seepage flow under hydraulic structures provided with intermediate filters has been investigated. The flow through the banks of the canal has been included in the model. Different combinations of intermediate filter and canal width were studied. Different lengths of the floor, differential heads, and depths of the sheetpile driven beneath the floor were also investigated. It was found that the introduction of an intermediate filter to the floor of hydraulic structures reduced the uplift force acting on the downstream floor by up to 72%. The maximum uplift reduction occurred when the distance of filter location downstream the cutoff to the differential head ratio was 1. Introducing a second filter in the downstream side resulted in a further reduction in the exit hydraulic gradient and in the uplift force, which reached 90%. The optimum locations of the two filters occurred when the first filter was placed just downstream the cutoff wall and the second filter was placed nearly at the mid27 distance between the cutoff and the end toe of the floor. The results showed significant differences between the three-dimensional (3D) and the two-dimensional (2D) analyses.