Effect of Seepage Barrier in Steady Seepage Below Earthen Dam by Centrifuge Modeling

Abstract

Modeling of prototype geo-structures such as slopes, embankments, retaining walls, piled foundations, and tunnels have been effectively done in a geotechnical centrifuge. The approaches of centrifuge modeling have facilitated the evaluation of seepage and deformation in the embankments and are also considered a powerful tool to examine the failure mechanisms. In this context, a model dam, made of clayey soil based on cross-sections of an earthen dam, in South 24 Parganas, West Bengal, India, has been studied with experimental modeling by centrifuge. The present study, therefore, has been carried out to analyze steady seepage condition in the case of a waterfront earthen embankment dam. The experimental study has been performed by centrifuge modeling, considering Scale factor N = 100 g, g being acceleration due to gravity. The model has been rotated at a speed of 400 rpm. In the experimental simulation, phreatic line, flow net, and stability against steady-state seepage in terms of factor of safety, have been obtained. The effectiveness of sheet pile as seepage barrier with varying sheet pile length and position for all cases, have been studied, with a variation of sheet pile length of 5, 10, 15, and 20 m varying the sheet pile position at B/8, 2B/8, and 3B/8 positions from the downstream end, B being the width of the dam. It has been observed that sheet pile length has a significant effect on fluid flow vector, a factor of safety along the sheet pile.