Results of an investigation of the adequacy of Pennsylvania's current design for highway underdrains and of specific materials used in the design are reported. Fine aggregate filter media, types A and B, were examined for their functional capabilities under relatively low hydraulic pressure gradients. Woven and nonwoven synthetic fabrics were investigated to detemine the feasibility of using them as a filter medium in the underdrain system. Perforated underdrain pipe was investigated to determine the minimum cross-sectional area of pipe to allow adequate outflow of anticipated inflow. Filter fabric materials appear to have a practical use in drainage systems. Recommendations include (a) further testing to evaluate the optimal combination of filterability versus permeability, the long-range effects on the permeability of filter fabric of contact with fine silt subgrade soils, and the most practical and effective installation procedures; (b) a minimum perforation area and a minimum pipe diameter; and (c) further investigation into changing subbase gradation specifications to make the material more permeable and eliminating fine aggregate backfill as a filter medium where heads of less than 0.3 m (less than 1 ft) are anticipated. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 32-43
  • Monograph Title: Moisture and frost-related soil properties
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00193798
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 11 1979 12:00AM