Conceptual analysis of seepage control for Senggarang Coastal Embankment with chemically-stabilized backfill

Abstract

One of the common problems of coastal embankments is water seepage. The Senggarang Coastal Embankment (SCE) is examined in the present work, with the objective of proposing the improvement of the earth structure via chemical stabilization. The stabilized soil embankment was simulated and analyzed with PLAXIS 8 to identify a conceptual proposition of solution using a conventional and innovative stabilizer, i.e., lime-ZnO and cement-CSP (cockle shell powder). The base of the embankment was assumed to be bedrock, in order to eliminate the passage of water below the embankment. Stabilization was taken as 100 % for the embankment, i.e., a homogeneous earth structure made entirely of stabilized soil for seepage mitigation. Input parameters for the simulations were acquired from both field samples and past studies. Varying water levels due to tidal effect were applied in the model to determine the changes of pore pressure distribution which could potentially lead to instability of the embankment. As water level increases with the rising tide, total displacement of the original earth embankment was found to increase as the soil weakened, with decreasing effective shear stress. Replacement of the embankment backfill with cement-CSP and lime-ZnO were both observed to significantly reduce the displacements. The use of both stabilizers not only improves the SCE’s engineering performance in terms of reduced water seepage and displacement, accompanied by increased strength, but the ‘green’ nature of the former, as derived from organic waste, also enhances the appeal of the stabilization technique.