DISCUSSION OF SKIN FRICTION FOR STEEL PILES IN SAND

THE AUTHORS ARE COMMENDED FOR THEIR PRESENTATION OF LABORATORY AND FIELD TESTS THAT HAVE PROVIDED BETTER INSIGHT INTO THE AREA OF PILE-SOIL INTERACTION. WHEN THE RATIOS OF SKIN FRICTION TO SOIL SHEAR STRENGTH FOR THE FIELD TEST ARE PLOTTED VERSUS DEPTH IN A PRESENTED FIGURE, AN INTERESTING RELATIONSHIP IS SHOWN. BASED ON THE RELATIONSHIP SHOWN FOR THIS PARTICULAR PILE GEOMETRY, SURFACE ROUGHNESS AND SOIL TYPE, IT CAN BE SAID THAT THE RATIO DECREASES WITH DEPTH TO ABOUT 40 FT BELOW WHICH IT BECOMES QUASI-CONSTANT. THE AUTHOR PRESENTED FIGURES WHICH SHOW THAT THE PEAK VALUES OBTAINED FOR THE LOOSE SATURATED SAMPLES COMPARE FAVORABLY WITH THE PEAK VALUES OBTAINED WITH THE DENSE SATURATED SAMPLES. THIS MIGHT INDICATE THAT THE LOOSE SAND STRUCTURE COLLAPSED AND DENSIFIED AS IT WAS BEING SATURATED. THE EFFECT OF SATURATION ON THE PEAK LOADS IN THE DENSE SPECIMENS IS NOT READILY APPARENT. THE LATTER PORTIONS (BEYOND 0.05-IN. DISPLACEMENT) OF THE SATURATED SPECIMEN CURVES ARE PARALLEL. THIS IS ALSO THE CASE FOR THE DRY SPECIMENS. THE RATE OF GAIN OF SKIN FRICTION IN THIS REGION IS GREATER FOR THE SAMPLES THAT WERE SATURATED. THIS SEEMS CONTRARY TO THE AUTHORS' CONCEPT OF WATER LUBRICATING THE PILE-SOIL INTERFACE. OTHER STUDIES USING MODEL PILES IN CLAY HAVE SHOWN THAT AFTER THE PEAK LOAD WAS MOBILIZED, THE LOAD DECREASED SLIGHTLY BUT REMAINED CONSTANT THEREAFTER. COMMENT IS REQUESTED BY THE AUTHORS ON WHY THE SKIN FRICTION IN SAND CONTINUED TO INCREASE LINEARLY WITH DISPLACEMENT AFTER THE PEAK LOAD WAS ACHIEVED. THE RESULT OF THE SATURATED- UNDRAINED TEST IS SOMEWAHT DUBIOUS. IT SEEMS LOGICAL TO BELIEVE THAT THE LOOSE SATURATED-UNDRAINED PILE-SOIL SYSTEM SHOULD HAVE TESTED LOWER THAN THE LOOSE SATURATED-DRAINED TEST BECAUSE OF THE DIALATANT NATURE OF SAND. OTHER THINGS MAY HAVE COMPLICATED THE TEST AS MENTIONED. ANOTHER ASPECT OF A PILE DRIVEN INTO SAND TO BE CONSIDERED IS THE INTERACTION OF THE PILE POINT. WHILE IT IS GENERALLY ACKNOWLEDGED THAT THE LOAD CARRIED AT THE POINT INFLUENCES THE SKIN FRICTION MOBILIZED ON THE SHAFT, IT IS NOT KNOWN FOR WHAT DISTANCE. REFERENCES: SKIN FRICTION FOR STEEL PILES IN SAND, H. M. COYLE AND I. H. SULAIMAN, ASCE, (PROC. PAPER 5590), NOVEMBER 1967.

  • Supplemental Notes:
    • Vol 95, No SMI, PP 371-374, 1 FIG, 4 REF, 2 APP
  • Corporate Authors:

    N/A

    ,   United States 
  • Authors:
    • Raba, C F
    • Garner, C W
    • Davisson, M T
  • Publication Date: 0

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  • Accession Number: 00232675
  • Record Type: Publication
  • Report/Paper Numbers: No SM5, Proc Paper 490
  • Files: TRIS
  • Created Date: Aug 15 2004 2:44AM