Innovate Driven Pile Solution for the Rhode Island Route 6/10 Interchange Project-Paper

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The Route 6/10 Interchange reconstruction in Providence, Rhode Island, required foundations in deep granular soils above bedrock more than 200 feet below grade. Drilled micropiles were initially proposed because of limited access and headroom. After reviewing prior local testing and conducting analyses, the project team evaluated driven steel Tapertube piles as a potentially faster, lower-cost alternative.<br /><br />A 2018 test program compared 16-inch Tapertube and steel pipe piles at two sites with differing soil profiles. Piles were monitored during installation and tested dynamically, then subjected to static compression, tension, and lateral loading. Embedded vibrating-wire strain gauges measured load transfer along the piles.<br /><br />Tapertubes outperformed pipe piles in axial capacity. Compression tests measured ultimate capacities of 430 and 560 kips for Tapertubes, versus 350 and 280 kips for pipe piles. Tapertube tension capacities were also about 50% higher, while lateral performance was similar. Measurements showed that Tapertubes mobilized substantial resistance along their tapered sections. Driving stresses remained within allowable limits, and measured vibrations were low.<br /><br />Compared with the proposed micropiles, Tapertubes provided much greater capacity and performed well under uplift and lateral loads. Their use reduced the estimated number of foundation elements per pier from 60–80 micropiles to 20–30 driven piles, and installation time from a budgeted 25–30 days to 2–4 days per substructure. The study concludes that Tapertubes can be an effective, economical option in deep, medium-dense granular soils common across southern New England.

Keywords

Route 6/10 Interchange

Providence Rhode Island

deep granular soils

bedrock

drilled micropiles

driven steel Tapertube piles

foundation reconstruction

static load testing

axial capacity

southern New England