Caissons in Cohesionless Soils Considering 3D Wedge under Earthquake Loading

Abstract

Ultimate soil resistance that acts on a seismically induced caisson foundation and its distribution along the caisson height have been formulated by considering passive wedge failure analysis for both dry and submerged conditions. The method for limiting the equilibrium of forces acting on a three-dimensional idealized passive wedge developed due to seismicity has been adapted in this study. Using this process, seismic inertia forces will be computed by considering the surrounding soil as a viscoelastic material that overlays a rigid stratum subjected to a harmonic shaking. For a very large value of caisson width, the comparison of this analysis with a 2D seismic earth pressure problem illustrates the compatibility of this methodology in the plane strain condition. Variation in earth pressure coefficients and their distribution for different seismic acceleration coefficients, soil properties, excess pore pressure ratios, and caisson aspect ratios will be discussed in this analysis. The reasonable agreement of the distribution of total passive pressure along the wedge height under the submerged condition with the experimental results shows the applicability of the proposed formulations as a design approach for caissons in sandy soil.