WATER DRAINAGE FROM HIGHWAY FILLS

One or more layers of poorly graded limestone blocks was found in each fill that was studied in detail. These layers of rocks contained much open space between blocks which acts as a reservoir for water moving into the fill. Water is induced through surface cracks, animal burrows, and bowl or funnel shaped depressions and ends up in the rock layers over a period of time the water gradually soaks the shale and soil used in the fill embankment resulting in unstable fill conditions especially those with steep slopes. This in turn sometimes results in a fillslide. Montmorillonite clay was probably a major factor in one slide but the clay minerals present were likely only one of several additive factors that produced the other slides. The concentration of water in the limestone block layers was an important factor in all of the slides. Vertical and horizontal drains have been used to drain millions of gallons of water from these fills thus improving the stability for as long as four years until the slides could be repaired. Special plantings of trees and shrubs are being tried on reconstructed slopes to aid in removing excess water and help bind the fill material with their root systems. A volunteer growth of trees along with vertical drains have stabilized one slide for several years and no other repair is needed. Inclinometer studies on one repaired slide shows a slow and gradual downward movement of the surface material that is typical of soil creep. Changes have been suggested for the specifications on the use of rock in embankments in Kansas. It was suggested that limestone blocks not be used in the top three feet of fills but should be placed in the base of the fill or on the face of the fill slope. Whenever limestone is placed is a fill the blocks should extend to the outside of the fill to allow positive external drainage. /FHWA/

• Supplemental Notes:
  • Prepared in cooperation with the Federal Highway Administration.
• Corporate Authors:

  Kansas Department of Transportation

  Engineering Services Department, State Office Building
  Topeka, KS  United States  66612
• Authors:
  • Clark, P C
  • Wineland, J D
  • Gilliland, W J
  • Crumpton, C F
• Publication Date: 1978-12

Media Info

• Pagination: 27 p.

Subject/Index Terms

• TRT Terms: Clay; Creep; Drainage; Fills; Highways; Limestone; Montmorillonite; Planting; Rockslides; Slope stability; Slopes; Soil mechanics; Soil stabilization
• Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology;

Filing Info

• Accession Number: 00189486
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Report/Paper Numbers: FHWA-KS-78-4 Final Rpt., FCP 4053-802
• Contract Numbers: Study No. 72-1
• Files: TRIS, USDOT, STATEDOT
• Created Date: Apr 12 1979 12:00AM