Helical Pile Use as Foundation Support for High Speed Profiler Equipment-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes foundation design for high-precision manufacturing equipment at Philadelphia’s Navy Yard, including high-speed profilers. Because the machines require extremely tight foundation tolerances, estimated settlement of shallow mat foundations—about 2.4 to 3.2 inches through thick silt deposits—made deep foundations necessary.<br /><br />Subsurface investigations at nine foundation locations identified variable silt thicknesses, influencing pile lengths. The selected systems were 16-inch-diameter Stelcor drilled-in displacement micropiles (DDMs) at Buildings 20 and 1029, and 16-inch-diameter auger-cast piles at Building 546. DDMs were chosen in part for their smaller installation rig and practical installation rate.<br /><br />Full-scale pile load tests established allowable DDM capacities of 40 tons at 25- and 30-foot bond lengths, and 55 tons at a 35-foot bond length. Additional piles at Buildings 1029 achieved 55-ton allowable capacity at embedments of 39 and 41 feet. Foundation-base deflection testing at six locations applied loads of up to 130 tons. Measurements met the specified tolerance of 0.04 mm per meter at that load.<br /><br />Key lessons included the importance of representative load-test conditions, which were best achieved by testing at the existing slab grade. DDMs performed successfully in both uniform grids and load-based layouts. Gross settlement ranged from approximately 0.5 to 2 inches at twice design loads. Dense gravel occasionally obstructed installation, and locations with thicker silt required longer piles.

Keywords

foundation design

high-precision manufacturing

Navy Yard Philadelphia

micropiles

drilled-in displacement micropiles

auger-cast piles

settlement tolerance

load testing

silt deposits

deep foundations