Field Verification of Undercut Criteria and Alternatives for Subgrade Stabilization-Coastal Plain

Details

• Creators:
  Cowell, Timothy D. ; Pyo, Sang Chul ; Gabr, Mohammed A. ; Borden, Roy H.
• Corporate Creators:
  North Carolina State University. Department of Civil, Construction, and Environmental Engineering
• Corporate Contributors:
  North Carolina. Dept. of Transportation. Research and Analysis Group
• Subject/TRT Terms:
  Cement Cement Stabilization Coastal Engineering Cost Effectiveness Costs Earth Pressure Cells Field Tests Full-scale Testing Geosynthetics Laser Radar LiDAR Performance Cost Performance Tests Plains Soil Stabilization Subgrade (Pavements) Subgrade Materials Testing Undercut

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• Publication/ Report Number:
  FHWA/NC/2008-13
• Resource Type:
  Tech Report
• Geographical Coverage:
  North Carolina
• Edition:
  Final report; Aug. 2010-June 2012.
• Corporate Publisher:
  North Carolina. Dept. of Transportation
• Abstract:
  The North Carolina Department of Transportation (NCDOT) is progressing toward developing quantitative and systematic
  
  criteria that address the implementation of undercutting as a subgrade stabilization measure. As part of this effort, a
  
  laboratory study and numerical analysis were performed from 2008 to 2010 with the results providing proposed criteria for
  
  undercutting under various roadway site conditions and the adequacy of stabilization measures typically employed if
  
  undercut was deemed necessary. These criteria provide provisions for discerning possible rutting and pumping of the
  
  subgrade under construction loading, and provide response and subgrade stiffness under repeated loading of 10,000 cycles.
  
  The work in this report is focused on performing full-scale testing in the field on instrumented unpaved roadway sections to
  
  collect data for the validation of guidelines developed from the laboratory and modeling study. Four 16 feet wide by 50 feet
  
  long stabilized test sections were built on poor subgrade soils encountered in the Coastal Plain region of North Carolina.
  
  One test section encompassed undercutting and replacement with select material (Class II), the second and third test sections
  
  included reinforcement using a geogrid and geotextile, respectively, in conjunction with undercutting and replacement with
  
  ABC (Class IV), and a fourth test section included cement treatment of the soft subgrade soil. Full-scale testing was
  
  conducted on the test pad by applying 1000 consecutive truck passes using a fully loaded tandem-axle dump truck over a
  
  period of four days. During this time visual observations were noted and measurements were collected regarding rut depth,
  
  vertical stress increase at the base/subgrade interface, and subgrade moisture content with truck passes. Once trafficking
  
  was completed, the test pad was re-graded and proof roll testing was performed to look for signs of pumping and rutting.
  
  Based on the field results, the proposed undercut criteria are evaluated in regards to the ability to discern the need for
  
  undercutting as well as predict the performance of the stabilized test sections. Finally, a performance cost analysis is
  
  conducted to illustrate the relative cost of each stabilization measure in relation to the measured performance (rutting) such
  
  that an informed decision on cost-effective subgrade stabilization can be made.
  
  
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:9ee4e08b352d1e16fa53e210f954c609f5b062a64c59fde760f985675a730d09
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/24765/dot_24765_DS1.pdf
• File Type:
  [PDF - 9.72 MB ]