Stability of Earthen Embankment with Clay Core Under Tidal Fluctuation

Seepage through and below earth dam plays an important role in determining the stability of earthen embankment. Stability analysis during rapid drawdown is an important aspect in earthen embankment. Reducing porewater pressure through improved drainage could possibly ensure longer life of embankments. Introduction of filters, drains, clay blankets, clay core, and flatter side slopes are the potential remedial measures to avoid the failure of embankment, due to seepage. Out of these provision of an embankment core is an economic solution. The embankment core is usually installed at the center of the embankment, has significance in controlling the seepage through embankment body. In the present investigation stability analysis of an embankment using clay core under tidal fluctuation has been studied. The current study has been done by seepage and stability analysis of a typical section of an embankment with base width of 17 m and side slope 2(H):1(V) made of homogeneous soil, under rapid drawdown condition. The study has been done by finite element method using SEEP/W software varying thickness of thin clay core of embankment. Pore pressure variations, Flownet, and Phreatic surface have been obtained for the numerical models by SEEP/W software. In this study the pore pressure development of the embankment, by a mixed clay core of different thicknesses, is investigated and evaluated. The stability of the slope during water level drawdown conditions has also been analyzed, considering the variation of porewater pressures calculated from the transient seepage analysis. It has been observed that, factor of safety against slope failure, decreases when river side slope of the embankment is subjected to drawdown condition. The paper brings out the effect of variation on thickness of thin clay core on improvement of stability of earthen embankments through numerical modeling.