SMOOTH LANDINGS FOR GIANT HOVERCRAFT

THE SRN 4 HOVERCRAFT WHICH CROSSES THE CHANNEL BETWEEN FRANCE AND BRITAIN CARRIES 250 PASSENGERS AND 30 CARS AND WEIGHS 170 TONS WHEN LOADED AND MOVED ON A CUSHION OF AIR RETAINED BY A FLEXIBLE SKIRT. THE DESIGN OF THE LANDING APRONS AND PARKING AREAS FOR THE HOVERCRAFT WAS THE RESULT OF STUDIES CARRIED OUT BY THE FRENCH BITUMES SERVICE AND MARITIME SERVICE. TWO SLIPWAYS WERE NEEDED, EACH 90 YARDS LONG AND 100 YARDS WIDE. THESE WERE BUILT OF SAND, WITH AN ASPHALT REVETMENT. ONE OF THE MOST IMPORTANT FEATURES OF AN ASPHALT REVETMENT IS THE TOE SUPPORT. THE TOE MUST RESIST EROSION AT LOW TIDE, AND THE CONSTRUCTION CHOSEN CONSISTS OF STEEL SHEET PILING 8 FEET HIGH, TOPPED BY A CONCRETE INTER-TIE. A FLEXIBLE REVETMENT 14 FEET WIDE WAS PLACED IN FRONT OF THE SHEET PILING. THIS REVETMENT CONSISTED OF LARGE STONES GROUTED WITH ASPHALT MASTIC. TO WITHSTAND THE ACTION OF THE SEA AND TO BALANCE ANY HYDROSTATIC PRESSURE, IT WAS DECIDED THAT THE REVETMENT SHOULD BE OF IMPERVIOUS ASPHALTIC CONCRETE. THE THICKNESS OF THIS LAYER WAS DETERMINED BY THE DUTCH METHOD WHICH GIVES THE THICKNESS OF ASPHALT REVETMENT NEEDED TO RESIST THE BENDING STRESSES AT THE MOMENT OF IMPACT OF WAVES CORRESPONDING TO MAXIMUM SWELL. BASED ON EXPERIENCE GAINED ON DUNKIRK HARBOUR WORK, IT WAS DECIDED TO USE A DISCONTINUOUS (GAP) GRADING FOR THE ASPHALTIC CONCRETE MIX, BECAUSE THIS OFFERED A NUMBER OF ADVANTAGES OVER A CONTINUOUSLY GRADED MIX. THE GAP GRADING PROVIDES A VERY SMOOTH, CLOSE-TEXTURED SURFACE, IDEAL FOR HOVERCRAFT OPERATIONS BECAUSE IT REDUCES WEAR ON THE SKIRTS. THE MIX WAS LAID IN TWO LAYERS. AS A FINAL SURFACE, A 4 INCH LAYER OF MIX WAS LAID, USING NORMAL PAVERS, AND THIS WAS COMPACTED BY STEEL-TIRED ROLLERS.

  • Supplemental Notes:
    • pp 10-12, 1 FIG, 2 PHOT
  • Corporate Authors:

    National Asphalt Pavement Association (NAPA)

    5100 Forbes Boulevard
    Lanham, Maryland  United States  20706
  • Publication Date: 1970-1

Subject/Index Terms

Filing Info

  • Accession Number: 00211471
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 4 1970 12:00AM