A Case Study to Evaluate the Capacity of H-Pile Reinforced Auger Cast Pile Utilizing Bi-directional Load Testing-PPT Presentation

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The case study evaluated H-pile-reinforced auger-cast piles for the DART Silverline Project, a 26-mile regional rail line connecting seven cities. Auger-cast piles were being considered for six bridges, representing a new foundation type for DART.<br /><br />The site consists of alluvial soils—primarily lean and fat clay, with sandy clay and occasional clayey sand—over Eagle Ford bedrock, with a shallow groundwater table. Compared with drilled shafts, auger-cast piles can be faster and more cost-effective, avoid open-hole construction, and require no casing, though installation is more complex and depends on suitable ground conditions.<br /><br />The project had three objectives: demonstrate that auger-cast piles could be properly installed in the site geology, verify that H-piles could be installed with adequate alignment, and assess pile ultimate capacity. Two test piles were installed at Bridges 11 and 17 and evaluated using bi-directional static load testing. The tests examined load and displacement over time, load distribution, unit side resistance, and end bearing. Thermal integrity testing was also conducted.<br /><br />The study concludes that bi-directional load testing can effectively assess pile axial capacity and determine unit side resistance and end bearing, supporting more confident and efficient foundation design. Compared with conventional static testing, this approach requires less space, does not need multiple reaction piles, and avoids heavy equipment for the test setup. The document provides no numerical test results.

Keywords

H-pile

auger-cast piles

DART Silverline Project

bi-directional static load testing

foundation design

axial capacity

unit side resistance

end bearing

alluvial soils

thermal integrity testing