Calculating Pile Downdrag: Experimental and Numerical Investigations

The goal of this research is to investigate pile downdrag in consolidating ground using fully instrumented lab-scale pile tests and finite element numerical modeling. Pile foundations embedded in consolidating soil profiles (i.e., soil experiencing settlement due to surcharge loading, groundwater level drop, liquefaction, etc.) are subject to increased axial loads (i.e., drag load) and pile settlements (i.e., downdrag). Downdrag has been reported to have caused extreme foundation movements, differential settlements, and extensive damage to various structures in south-central states. State DOTs are facing a design challenge about inconsistency design codes (i.e., AASHTO LRFD Bridge Design Specifications and FHWA Driven Pile Manual) to predict drag load and downdrag. Although several field monitoring programs in the literature were successfully conducted on piles under downdrag, fully instrumented lab-scale pile tests focusing on the responses at the soil-pile interface is still lacking, which will be investigated in this project. This research focuses on investigating the soil-pile interaction (e.g., downdrag, drag load at the soil-pile interface, and location of the neutral plane) using S3F interface shear stress sensors, strain gauges, and settlement plates. The test results will be used to calibrate a numerical modeling tool that can accurately predict downdrag and drag load along the pile. This research is relevant to Tran-SET’s vision and mission because the investigation of pile behavior under downdrag will help improve the inconsistent design specifications, avoid overly conservative design, reduce the construction cost, and result in more sustainable and resilient geotechnical infrastructure. Downdrag design is ubiquitous in Region 6 states. The test results of this research will update the current design specifications of downdrag calculation. This research will also develop a ready-to-use numerical modeling tool. This modeling tool will be disseminated to state DOTs, consulting firms, and industry communities at the end of this project. The outcome of this research will contribute to workforce development. The research team will focus on educating professional engineers using the short course, webinars, technical publications, and conference presentations. The outcome of this research will also be incorporated into the LSU online Master of Science program in Civil Engineering, which attracts many state DOT engineers and industry professionals.

• Record URL:
  https://transet.lsu.edu/research-in-progress/
• Supplemental Notes:
  • 20GTLSU10

Language

• English

Project

• Status: Completed
• Funding: $ 90042
• Contract Numbers:

  69A3551747106

• Sponsor Organizations:

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Managing Organizations:

  Transportation Consortium of South-Central States (Tran-SET)

  Louisiana State University
  Baton Rouge, LA  United States  70803
• Project Managers:

  Mousa, Momen

• Performing Organizations:

  Louisiana State University

  3660G Patrick F. Taylor Hall
  Civil and Environmental Engineering
  Baton Rouge, LA  United States  70803
• Principal Investigators:

  Lin, Hai

• Start Date: 20200801
• Expected Completion Date: 20220201
• Actual Completion Date: 0
• USDOT Program: University Transportation Centers Program

Subject/Index Terms

• TRT Terms: Axial loads; Drag forces; Finite element method; Laboratory tests; Pile foundations; Settlement (Structures)
• Subject Areas: Bridges and other structures; Design; Geotechnology; Highways;

Filing Info

• Accession Number: 01757496
• Record Type: Research project
• Source Agency: Transportation Consortium of South-Central States (Tran-SET)
• Contract Numbers: 69A3551747106
• Files: UTC, RIP
• Created Date: Nov 10 2020 3:27PM