Hybrid A-Frame Micropile-Geosynthetic Reinforced Wall with Impact Barrier: Design Development and Construction Approach

This report presents the results of a comprehensive evaluation of a hybrid A-frame micropiles-geosynthetic reinforced soil (GRS) wall design to support roadways with TL-4 impact road barriers on mountainous roads and its accompanying engineering options in dealing with the foundation stability problems in road widening and construction projects. Extensive numerical simulations of mechanically stabilized earth (MSE) walls were conducted by 3D nonlinear computer modeling using an advanced finite element code and an elastoplastic soil model that has been well calibrated in past National Cooperative Highway Research Program (NCHRP) and Colorado Department of Transportation (CDOT) projects. Collaborated partially by an experimental scaled model study that substantiated the general applicability of the modeling platform, the performance of the hybrid design under self-weight, surcharge and dynamic impacts was investigated in detail and compared with that of a truncated GRS wall with regular construction. The available option of using the A-frame micropile as an integrated solution to the related local slope-foundation stability problem that can be triggered by the wall construction was explored and quantified by the large-deformation analysis with the aid of the new threshold effective strain concept whose validity was demonstrated against ordinary limit-equilibrium slope stability methods in benchmark settings. While there remains engineering details to be explored and more realistic representation of material components to be incorporated, the study has shown that the hybrid wall design offers potential as a new or remedial engineering option in coping with difficult hillside or steep terrain conditions for road expansion or new projects.

• Record URL:
  • https://www.codot.gov/programs/research/pdfs/2018-Research-Reports/2018-11/view
• Supplemental Notes:
  • Cover date: November 2018.
• Corporate Authors:

  University of Colorado, Boulder

  Department of Civil, Environmental and Architectural Engineering
  Boulder, CO  United States  80309-0428

  Colorado Department of Transportation

  Denver, CO  United States  80222

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Pak, Ronald Y S
  • Zhang, Zhichao
• Publication Date: 2018-5-15

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Figures; Photos; References; Tables;
• Pagination: 74p

Subject/Index Terms

• TRT Terms: Barriers (Roads); Deformation; Design; Earth walls; Evaluation and assessment; Finite element method; Geosynthetics; Mechanically stabilized earth; Mountain roads; Road construction; Slope stability
• Uncontrolled Terms: Micropiles
• Subject Areas: Bridges and other structures; Construction; Design; Geotechnology; Highways;

Filing Info

• Accession Number: 01690838
• Record Type: Publication
• Report/Paper Numbers: CDOT-2018-11
• Contract Numbers: 214.03
• Files: TRIS, ATRI, USDOT, STATEDOT
• Created Date: Jan 15 2019 10:42AM