Standardizing Rigid Inclusions for Transportation Projects — Phase I

Details

• Creators:
  Han, Jie ; Lamsal, Sameep ; Chen, Haohua ; Parsons, Robert L. ; Ye, Yuqiu
• Corporate Creators:
  University of Kansas. Dept. of Civil & Environmental Engineering
• Corporate Contributors:
  Kansas. Dept. of Transportation. Bureau of Research ; Idaho Transportation Department ; Louisiana. Department of Transportation and Development ; Maryland. Department of Transportation ; Minnesota Department of Transportation ; Pennsylvania. Department of Transportation ; Texas Department of Transportation
• Subject/TRT Terms:
  Columns Design Embankments Rigid Structures Soil Stabilization Standardization State Of The Practice Structural Supports
• Publication/ Report Number:
  FHWA-KS-25-02
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Kansas ; Iowa ; Minnesota ; Pennsylvania
• Edition:
  Final Report: June 2023 – November 2025
• Corporate Publisher:
  Kansas. Dept. of Transportation. Bureau of Research
• Abstract:
  Rigid inclusions (RIs) have increasingly been used in ground improvement technology in the United States because they effectively reduce settlement, increase bearing capacity, and enhance stability. Several design methods have been developed to analyze RI-supported embankments based on various assumptions for transportation applications. This study assessed the state of the practice of RIs for embankment and structure support in transportation projects, including construction specifications, installation effects, slope stability, and design methods for vertical load transfer. An internet survey was conducted to gather opinions from owners, engineers, and researchers in the United States. Evaluation of the design methods involved a comparison of results calculated from the popular design methods BS 8006- 1, EBGEO, CUR226, and the Federal Highway Administration (FHWA) for three key design parameters (load efficacy, differential settlement and reinforcement strain). The measured data were available in the literature, including 24 full-scale experiments and four model tests. The comparison results revealed variations and inconsistencies of the calculated results among the design methods. Numerical analyses were also performed for two case studies, and their results were compared with the results from the design methods. Methods CUR226 and FHWA comparatively more accurately predicted all three design parameters, while BS 8006-1 overestimated all these parameters. This study also utilized the Column-Wall Method (CWM), Equivalent Strength Method (ESM), Stress Reduction Method (SRM), and Pile Support Method (PSM) to evaluate the stability of RIS embankments. The results showed that the ESM led to a high strength of the equivalent area that prevented deep-seated failure. The SRM overestimated the factors of safety (FS) by more than 10% compared to those from the CWM while the PSM significantly overestimated the FS as compared to the CWM. This study reviewed the effects of RI installation on existing adjacent structures based on a limited number of documented case studies. This study also summarized the special provisions for RI projects of four state departments of transportation, identified the knowledge gaps in the current practice, and developed a plan for second-phase field evaluation of RIs for embankment/wall supports.
• Format:
  PDF
• Funding:
  C2218
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:2e3d87facb3bb73c7a28aedf134a402697ffa8b83f7470fc56f3df92cebc03c585489dca120ddac7e284bd6d8d519146243683fe6b9f250bce47656a33d60caa
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/88385/dot_88385_DS1.pdf
• File Type:
  [PDF - 6.60 MB ]