Numerical Analysis of Pile-Supported T-Walls Subject to Large Settlements and Flood Loading-Paper

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The study uses two-dimensional FLAC numerical analyses to examine how soil settlement and flood loading affect the piles supporting concrete T-walls in levees. Three otherwise identical cross-sections were modeled, with the T-wall base at the levee foundation, 10 ft above it, or atop the 15-ft levee embankment. Each wall was supported by two fixed-connected batter piles extending through compressible clay layers. Analyses simulated consolidation under levee construction, followed by a 25-ft flood load.<br /><br />Settlement alone caused inward pile bending and significant downdrag. The wall installed atop the levee fill experienced the largest settlement-induced bending moments and axial loads; placing the wall at the foundation level produced the smallest. Flood loading substantially changed pile responses: it increased maximum flood-side pile moment magnitudes by an average of about 34%, shifted their locations, and reduced flood-side axial loads—sometimes putting a pile in tension. Protected-side pile responses varied among configurations, demonstrating that the interaction of settlement and flooding is complex.<br /><br />The authors conclude that settlement-induced forces can reduce a pile’s capacity to resist flood loads. Designers should analyze settlement and flood loading together rather than combine peak values from separate analyses, and should minimize settlement-driven pile bending where feasible. A key recommendation is to install T-walls directly on foundation soils, rather than within or on top of newly placed fill.

Keywords

FLAC numerical analysis

pile settlement

flood loading

T-wall levees

concrete levee walls

batter piles

consolidation settlement

downdrag

pile bending moments

levee design