Sheet Pile Tensions in Cellular Structures

Cellular structures constructed of interlocking steel sheet piles are used in marine environments as cofferdams, bulkheads, mooring dolphins, and lock guide walls. In addition to providing safety against sliding, bearing failure, overturning, and tilting, cellular structures must also be designed to prevent sheet pile interlock rupture, which can lead to catastrophic failure if the cell fill is lost. Methods commonly used to estimate sheet pile interlock tensions were developed in the 1940ʹs, 1950ʹs, and 1970ʹs. These methods are based on empirical observations, and they do not explicitly account for soil–structure interactions. This paper presents the results of finite element analyses and instrumentation measurements performed to examine soil–structure interaction effects on sheet pile tensions. The finite-element analyses were used to compute sheet pile tensions at five instrumented cells, and the results are compared with measurements. The calibrated finite-element model was then used to investigate the effects of varying cell geometry, interlock behavior, sheet pile penetration depth, and foundation stiffness on sheet pile tensions. The instrumentation measurements provide data for estimating changes in sheet pile tensions due to cell fill densification, cofferdam unwatering, and bulkhead backfilling.