LABORATORY EVALUATION OF MATERIALS AND DESIGN CHARACTERISTICS OF PENNDOT UNDERDRAIN SYSTEM

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