NEGATIVE SKIN FRICTION ON PILES

STRUCTURES FOUNDED ON LONG END-BEARING PILES THROUGH EMBANKMENT FILLS AND UNDERLYING SOFT, COMPRESSIBLE SOILS MUST BE THOROUGHLY STUDIED FOR THE POSSIBLE REDUCTION IN LOAD CAPACITY OF THE PILES DUE TO "DRAG" LOADS. THESE "DRAG" LOADS, WHICH ARE ADDITIONAL FORCES TO THE NORMAL DEAD AND LIVE STRUCTURE LOADINGS, WILL DEVELOP WITH THE CONTINUED COMPRESSION OF THE FOUNDATION SOILS DUE TO THE EMBANKMENT FILLS OR DUE TO GROUNDWATER LOWERING. AS THE FOUNDATION SOIL COMPRESSES, SHEAR STRESSES ARE INDUCED BETWEEN THE ESSENTIALLY "FIXED" PILE AND THE CLAY WHICH MOVES VERTICALLY DOWNWARD RELATIVE TO THE PILE. IN PARTICULAR, (1) 100 PERCENT OF THE CALCULATED NEGATIVE SKIN FRICTION MUST BE TAKEN INTO ACCOUNT WHERE ANY SETTLEMENT IS EXPECTED FOLLOWING INSTALLATION OF FOUNDATION PILES UNLESS FULL SCALE FIELD TESTS ALLOW REDUCTION; (2) PILE DRIVING OPERATIONS SHOULD COMMENCE ONLY AFTER ALL SURCHARGE FILLS HAVE BEEN REMOVED AND THE EMBANKMENTS HAVE ACHIEVED MAXIMUM STABILITY; (3) PIPE PILES SHOULD BE INSTALLED OPEN-ENDED AND CLEANED OUT AS THEY ARE ADVANCED; AND (4) IF PIPE PILES MUST BE INSTALLED CLOSE-ENDED OR PRIOR TO THE REMOVAL OF SURCHARGE FILLS, THEY SHOULD BE PRE-AUGERED THROUGH THE CLAY LAYER TO ELIMINATE THE POSSIBILITY OF LOCAL SHEAR FAILURES CAUSED BY EXCESSIVE PORE PRESSURES DEVELOPED IN AREAS ADJACENT TO PILE DRIVING OPERATIONS. /AUTHOR/

  • Authors:
    • Gedney, D S
  • Publication Date: 1971-8

Media Info

  • Features: References;
  • Pagination: p. 29-33
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00233255
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 29 1972 12:00AM