Guidelines for Use and Design of Deep Foundations for Three-Sided Structures

Details

• Creators:
  Wang, Yao ; Salgado, Rodrigo ; Prezzi, Monica
• Corporate Creators:
  Purdue University. Joint Transportation Research Program
• Corporate Contributors:
  Indiana Department of Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Backfill Soils Finite Element Method Guidelines Live Loads Structures Support Piles Surveys Three-sided Structure
• Publication/ Report Number:
  FHWA/IN/JTRP-2026/07
• DOI:
  https://doi.org/10.5703/1288284318615
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Edition:
  Final Report
• Corporate Publisher:
  Purdue University. Joint Transportation Research Program
• Abstract:
  Buried three-sided structures are widely used for roadway crossings and underpasses. Whereas spread footings are common, deep foundations are required when weak soils, scour risk, or site constraints exist. This study aimed to improve understanding of load-transfer mechanisms and develop guidance for the design of deep foundations supporting buried three-sided structures. A nationwide survey of 34 state DOT engineers and 12 three-dimensional finite element analyses were conducted. Results show that greater stem wall height and thicker earth cover lead to a more uniform live-load distribution between piles. The most critical condition occurs when the design truck is placed near the roadside, where piles beneath the loaded segment carry the greatest loads. When the truck is centered, the load distribution becomes nearly uniform, and the superposition principle approximately holds for well-designed to conservatively designed piles. Comparison with the traditional moment-of-inertia method indicates that the method overpredicts live loads by about 10%–50%. The study confirms that live-load moments are small enough to be neglected and that current design practice is conservative. These findings provide a rational basis for improved design guidance for pile-supported three-sided structures.
• Format:
  PDF
• Funding:
  SPR-4732
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:65c6ef9d51c05b33bb18c2430dc4f0843aeaff3ec01e0267a962c44e2b863b428733c26f5ce7e37fcd83062f14c5cb5344a65c260d4f34aa09a1809b81260644
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/92350/dot_92350_DS1.pdf
• File Type:
  [PDF - 6.80 MB ]