Physical modeling of settlement induced bending moments on pile founded floodwalls

Abstract

T-walls are pile-supported concrete floodwalls that are part of the New Orleans flood protection system. They are typically founded on long concrete or steel battered piles and include a sheet pile cut off for seepage and gradient control. The lack of sufficient lateral support from the compressible foundation soil, accompanied by relatively large expected lateral loads from storm surge, require that these support piles be battered. Since the soils in Southern Louisiana contain soft and compressible silt and clay, these floodwalls need to be designed to resist not only flood loads but also loads produced by consolidation of soft foundation soil under the weight of new fill placed on or near a T-wall during construction. This is commonly referred to as downdrag and induces additional bending moments on the piles. Currently, the effects of settlement and flood loads are analyzed separately and the maximum bending moments developed on the battered piles are superimposed, without accounting for the nonlinearities associated with the analysis of the system.