Advancing Foundations: Augered Cast-in-Place Bridge Foundations-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes replacing part of a bridge foundation in Canton, Ohio, with auger cast-in-place (ACIP), or continuous flight auger (CFA), piles. The site lies in a deep, highly permeable buried glacial valley with groundwater, loose gravelly soils, and complex existing foundations. Earlier construction and subsequent observations included seepage, pile-installation difficulties, and significant movement and damage to bridge components.<br /><br />The original design for one structure included 86 drilled shafts. After installation problems and a differing subsurface conditions claim, 38 pier shafts were replaced with 176 CFA piles. The alternative had to be economical, produce low vibration near existing structures, work in difficult soils and restricted headroom, and avoid penetrating a lower aquitard.<br /><br />A proof-of-concept program tested vertical and battered piles, including static load and thermal integrity tests. Early cage installation proved difficult, but results showed that grout consistency and admixtures were critical, spiral reinforcement could improve cage rigidity, and full-length cages could be installed in battered piles. A 380-kip static test demonstrated the required capacity.<br /><br />The completed work comprised 176 piles, each 55 feet long, installed in two phases. Forty-five were installed under low headroom, and 36 were battered. Testing included two static tests, six dynamic tests, and thermal integrity profiling on 58 piles. Successful delivery depended on experienced operators and inspectors, and accurate calibration of the grout pump and installation monitoring equipment.<br /><br />The presentation concludes that the testing program validated the design methods and calculated capacities. CFA piles proved to be an economical and viable bridge-foundation alternative under challenging ground and construction conditions, and should be considered in future foundation-type evaluations.

Keywords

bridge foundation

CFA piles

auger cast-in-place

continuous flight auger

drilled shafts

groundwater

glacial valley

static load test

thermal integrity profiling

battered piles