A Cofferdam Design with Finite Element Modeling Verification

In this paper, the stability and performance of a modified rectangular cofferdam under the altered design conditions are assessed using both conventional limit equilibrium and finite element analyses. The conventional analyses were first applied to evaluate wall stability and structural demands using apparent active earth pressures and passive resistance pressures determined by the soil wedge method. Finite element soil-structure-interaction analyses were then performed to verify the results under different seepage and structural stiffness scenarios. Studies show that seepage would reduce the stability of the cofferdam and wall/strut stiffness significantly affects the computed earth pressures, bending moments, and safety factors. When structural components are assumed to be very stiff, finite element modeling produces similar results to conventional analyses. However, with realistic stiffness, the finite element analysis provides more reliable predictions of cofferdam performance. Finite element verification analyses provide more insights into the performance behaviors of the modified cofferdam and support safe and economical design with an accelerated construction schedule.