Role of Stratigraphy in Cut Slope Design for Horizontally-Bedded Sequences of Competent and Incompetent Rocks of Eastern Ohio

In this paper the authors will discuss that geology in Ohio is characterized by horizontally‐bedded sequences of competent and incompetent rock units (limestones, sandstones, siltstones, shales, claystones, and mudstones) that are highly prone to differential weathering and undercutting of the competent units by the incompetent units. Eighteen sites along eastern Ohio’s highways were selected to investigate the factors that need to be considered for cut slope design aimed at minimizing undercutting‐induced failures. The stratigraphy, slope geometry, and joint characteristics were investigated in the field, and slake durability index values for selected rock units from each site were determined in the laboratory. The stability of cut slopes subject to differential weathering was investigated with respect to three aspects: 1) the maximum amount of undercutting, 2) amount of rockfalls, and 3) fate and volume of rockfalls. Bi‐variate statistical analysis shows that the factors influencing the maximum amount of undercutting include distance of the undercut rock from the slope crest, joint spacing within the undercut rock unit, and slake durability index of the undercutting rock unit. The amount of rockfalls is influenced by the joint spacing within the undercut unit. Bedding thickness and joint spacing, which depend on lithology, jointly affect the fate as well as the volume of rockfalls. Shale units have higher slake durability index values. These lithological associations suggest the need for basing the cut slope design on stratigraphic details of rock sequences.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; Maps; Photos; References; Tables;
  • Pagination: pp 141-157
  • Monograph Title: Proceedings of the 60th Highway Geology Symposium

Subject/Index Terms

Filing Info

  • Accession Number: 01142311
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 20 2009 5:24PM