Effects of Soil Lateral Loading on Marine Structures

Pile=supported structures in marine environments such as piers and wharfs are subject to a variety of loading sources, intensities, and frequencies. These include vertical and lateral loading from service "day-to-day" loading, as well as less frequent live loads and environmental loading from wind and waves. The focus of this paper will be on a less frequently encountered loading that is equally important to consider - namely, the effects of soil lateral movement and subsequent lateral loading on existing pile supported marine structures. As older, existing facilities on the U.S. East Coast are repurposed or upgraded to accommodate larger Panamax ships, the phenomena of soil lateral loading may result from two commonly encountered condition states: 1) slope stability failure resulting from berth deepening and 2) seismic slope stability failure and lateral spread, which may not have been evaluated at the time the facilities were originally designed and constructed. Each condition state will be evaluated for an example structure modeled with soils typically encountered in the Charleston, South Carolina, harbor. The soil lateral loading components will be calculated, and a non-linear static structural analysis will be performed considering material and geometric non-linearity and soil-structure-interaction effects. Recommendations are then provided for design considerations for improvements to existing facilities.