The Seismic Design of Waterfront Retaining Structures

This technical report deals with the soil mechanics aspects of the design of waterfront retaining structures built to withstand the effects of earthquake loadings. It addresses the stability and movement of gravity retaining walls and anchored sheet pile walls, and the dynamic forces against the walls of drydocks and U-frame locks. The effects of wall displacements, submergence, liquefaction potential, and excess pore water pressures, as well as inertial and hydrodynamic forces, are incorporated in the design procedures. Several new computational procedures are described in this report. The procedures used to calculate the dynamic earth pressures acting on retaining structures consider the magnitude of wall displacements. For example, dynamic active earth pressures are computed for walls that retain yielding backfills, i. e., backfills that undergo sufficient displacements during seismic events to mobilize fully the shear resistance of the soil. For smaller wall movements, the shear resistance of the soil is not fully mobilized and the dynamic earth pressures acting on those walls are greater because the soil comprising the backfill does not yield, i.e., a nonyielding backfill. Procedures for incorporating the effects of submergence within the earth pressure computations, including consideration of excess pore water pressures, are described.