Construction Sequence for Settlement Control at Bridge End Bents and Reducing Drag Load on HP Piles-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes a construction sequence used to control settlement at bridge end bents and reduce downdrag on HP piles for the NCDOT U-5026/R-5720 project near the Atlantic Seaboard Fall Line. Local soils include terrace deposits of soft-to-medium-stiff silts and clays and loose-to-medium-dense sands over Piedmont residual soils and weathered rock.<br /><br />Under conventional construction, the estimated downdrag cutoff depth was 40 feet and pile drag load was 95 kips. The reported RnR values were 620 kips with limited PDA testing and 500 kips with sufficient PDA testing. With stage construction, the cutoff depth decreased to 20 feet and drag load to 12 kips; reported RnR values decreased to 440 and 350 kips, respectively.<br /><br />Settlement monitoring tracked an abutment wall and a roadway embankment. The presentation concludes that Piedmont residual silts and clays consolidate quickly, and that stage construction combined with pile restriking can reduce drag load. A pile restrike was recorded on December 21, 2022.

Keywords

bridge end bents

settlement control

downdrag reduction

HP piles

stage construction

NCDOT

PDA testing

pile restrike

Piedmont residual soils

abutment settlement