A DIFFERENT APPROACH TO BRIDGE APPROACH SLABS

DESIGN, CONSTRUCTION, AND MAINTENANCE OF BRIDGE APPROACH SLABS ARE A PROBLEM WHERE THERE ARE RECENT FORMATIONS OF NORMALLY LOADED SOFT CLAYS AND ASSOCIATED COMPRESSIBLE DEPOSITS. IF THE BEARING CAPACITY AND SHEAR STRENGTH OF THE COMPRESSIBLE DEPOSITS ARE VERY LOW, THEN EMBANKMENT STABILITY AND NONUNIFORM SETTLEMENT PROBLEMS BECOME APPARENT FOR ALL TYPES OF HIGHWAY EMBANKMENTS, NOT NECESSARILY LIMITED TO BRIDGE APPROACH SLABS. RECENTLY THE LOUISIANA DEPARTMENT OF HIGHWAYS DECIDED TO APPROACH THIS PROBLEM WITH A DIFFERENT METHOD OF ATTACK: IF SETTLEMENT CANNOT BE PREVENTED, IT CAN POSSIBLY BE KEPT UNDER CONTROL. TO ACCOMPLISH THIS, IT WOULD BE NECESSARY TO HAVE A STRUCTURAL TRANSITION FROM ONE MEDIUM INTO ANOTHER ALONG WITH A GEOMETRIC TRANSITION IN THE ROADWAY PROFILE. USING A 150-FOOT APPROACH SLAB SUPPORTED ON PILES OF DIMINISHING PENETRATION INSTEAD OF THE USUAL 20-FOOT APPROACH SLAB APPEARS TO BE A VERY PROMISING METHOD OF ACCOMPLISHING THE NECESSARY TRANSITION FROM A SOIL EMBANKMENT TO A BRIDGE DECK. IT IS BELIEVED THAT THE NEW APPROACH SLAB WILL BEHAVE JUST AS A BRIDGE DECK SITTING ON LONG PILES AT THE STRUCTURE END. BY GRADUALLY SHORTENING THE PILE PENETRATION TOWARDS THE EMBANKMENT END, THE LOAD WILL GRADUALLY SHIFT FROM THE PILES TO THE EMBANKMENT UNDER THE SLAB. AT THE EMBANKMENT END, THE APPROACH SLAB WILL BEHAVE JUST LIKE A CONCRETE ROADWAY SLAB FOLLOWING ANY DISPLACEMENT OR SETTLEMENT OF THE EMBANKMENT. THE LOUISIANA DEPARTMENT OF HIGHWAYS HAS FOUR PILE-SUPPORTED APPROACH SLABS UNDER CONSTRUCTION. THE APPROACH TO DESIGN AND CONSTRUCTION IS DESCRIBED VERY BRIEFLY.

  • Authors:
    • Kemahli, A S
  • Publication Date: 1971-8

Media Info

  • Features: Figures;
  • Pagination: p. 23-8
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00233254
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 29 1972 12:00AM