NUMERICAL ANALYSIS OF THE RESPONSE OF SOFT FOUNDATION SOILS UNDER TALL MBANKMENTSAND RETAINING WALLS

Abstract

The construction of tall embankments on soft soils requires staged construction, which leads to the consolidation of foundation soils, an increase in their effective stress, reduction in void ratio, and gain in shear strength. However, retaining walls and tall embankments are not fully constrained, which contributes to the generation of lateral movements that magnify vertical settlements of the embankments, potentially leading to global failure of the foundation soil and embankment system. This study systematically presents how material properties and retaining wall geometries influence the safety of the retaining walls-foundation soil system and the relationship between lateral movements to the magnitude of vertical settlement on retaining walls using numerical analyses and analytical methods. PLAXIS, a finite element package, is used for modeling and analyzing deformation of retaining walls and foundations. The methods presented herein are validated using different case studies from cross-sections of a newly constructed STH 29 / USH 41 interchange in the State of Wisconsin in the United States. Parametric studies were conducted that involved combinations of retaining walls and soft soil conditions to assess failure mechanisms and the contribution of lateral deflection to vertical settlement. These results are validated using vertical settlement measurements at the edge of the retaining walls and pore pressure measurements under the foundation soil.