PROTECTION OF THE SUBGRADE AGAINST THE EDGE EFFECT BY MEANS OF VERTICAL CAPILLARY SCREENS

PROTECTION DES SOLS DE FONDATION DES CHAUSSEES CONTRE L'EFFET DE BORD AU MOYEN D'ECRANS CAPILLIAIRES VERTICAUZX.

In most parts of Belgium where frost damage is not controlled, the winter edge effect is the main cause of pavement deterioration due to the weakness of the subgrade which has been saturated. The vertical capillary screen is a method of preventing this effect, particularly in the case of main and secondary roads too narrow to enable the stabilized shoulders to be waterproofed over a sufficient width. The vertical screen takes up very little room since it consists of a narrow trench, approximately 1M deep under the level of the roadbase. At its base a drainage pipe is inserted and filled with an appropriate material, which separates the subgrade from the stabilized shoulder. The material used for the screen is characterized by a suction and permeability variation curve which makes it practically impervious to water when it is operating under normal conditions, while remaining permeable to free water that can accidentally saturate the subgrade; the free water is evacuated by means of the pipe at the bottom of the trench. The effectiveness of the capillary screen was demonstrated using a laboratory two-dimensional model and on an experimental stretch of road where observations are still in progress. The latter experiment showed the need for protecting the screen against free water by means of edge joints. /TRRL/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00401277
• Corporate Authors:

  Association Permanente des Congres Belges de Route

  49 avenue d'Auderghem
  Brussels 4,   Belgium 
• Authors:
  • Brull, A
• Publication Date: 1974-12

Language

• Undetermined

Media Info

• Features: Figures; Photos; References; Tables;
• Pagination: p. 1-34
• Serial:
  • Technique Routiere
  • Volume: 19
  • Issue Number: 4
  • Publisher: Association Permanente des Congres Belges de Route
  • ISSN: 0040-1277

Subject/Index Terms

• TRT Terms: Building materials; Capillarity; Drainage; Durability; Experimental roads; Frost damage; Highway capacity; Laboratories; Mathematical models; Moisture content; Pavements; Permeability; Pipe; Pits; Prevention; Soil suction; Strength of materials; Subgrade (Pavements)
• Uncontrolled Terms: Models; Two dimensional; Vertical
• ITRD Terms: 5901: Capillarity; 2937: Drainage; 5509: Edge effect; 5702: Excavation pit; 2778: Experimental road; 6237: Laboratory (not an organization); 4555: Material (constr); 6205: Model (not math); 5920: Moisture content; 5921: Permeability; 9149: Prevention; 2950: Subgrade; 5771: Suction; 9083: Two dimensional; 9087: Vertical
• Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology; Pavements; Security and Emergencies; I26: Water Run-off - Freeze-thaw;

Filing Info

• Accession Number: 00157419
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Report/Paper Numbers: Analytic
• Files: ITRD, TRIS
• Created Date: Oct 13 1977 12:00AM