A MODEL INVESTIGATION OF FRICTION PILE CAPACITIES IN SILTS

A SERIES OF MODEL WOOD PILES AND PILE CLUSTERS WERE DRIVEN INTO COMPACTED BINS OF VERMONT SILT. THE PILES WERE INSTALLED AT A SLOW CONSTANT RATE OF PENETRATION WITH A CONTINUOUS RECORD OF PILE RESISTANCE VS PENETRATION DEPTH. LINEAR, TRIANGULAR AND RECTANGULAR GROUPS OF 2,3,4, AND 5 PILES WERE TESTED AT VARIOUS PILE SPACINGS. THEORETICAL METHODS WHICH CONSIDER THE STATIC EQUILIBRIUM OF THE PILE WITH WORKING LOADS AND ULTIMATE SOIL FORCES ARE OFTEN USED FOR PREDICTING PILE CAPACITIES. A REVIEW OF EARLIER WORK RELATED TO THE APPLICATION OF THIS STATIC EQUILIBRIUM METHOD TO PILE FOUNDATION DESIGN IS PRESENTED. THE RESULTS INDICATE THAT THIS THEORY, ALTHOUGH NOT WITHOUT ERROR, IS ACCEPTABLE FOR USE IN VERMONT SILT PROVIDED THAT DESIGN VALUES OF ADHESION AND SIDE FRICTION COEFFICIENT ARE SELECTED EMPIRICALLY. THESE DESIGN PARAMETERS DEPEND UPON FACTORS SUCH AS THE STRENGTH OF THE SOIL, PILE MATERIAL, TAPER, AND VOLUME DISPLACEMENT, AND IN-SITU EFFECTIVE STRESSES. EMPIRICAL VALUES OF ADHESION AND THE SIDE FRICTION COEFFICIENT FOR THE MODEL WOOD PILES IN VERMONT SILT COMPACTED AT VARIOUS WATER CONTENTS HAVE BEEN DETERMINED. THE MODEL PILE GROUP TESTS INDICATE THE SIGNIFICANT EFFECTS OF GROUP SIZE AND GEOMETRY AND PILE SPACING. THE RELATIVE IMPORTANCE OF SINGLE PILE STRESS BULB OVERLAP, AND UNIT OR BLOCKING ACTION AS DETERMINED BY THE GROUP SIZE, GEOMETRY AND PILE SPACING, INFLUENCES THE BEHAVIOR OF ALL PILE GROUPS. GROUP EFFICIENCIES GREATER THAN 100 PERCENT WERE OBSERVED. LINEAR PILE GROUPS DEVELOPED THE SMALLEST EFFICIENCIES. THE RECTANGULAR 5 PILE GROUP DEVELOPED LARGE EFFICIENCIES EVEN AT LARGE PILE SPACING. THE CAPACITY OF A TYPICAL FULL-SCALE WOOD PILE IN VERMONT SILT HAS BEEN CALCULATED USING THE THEORETICAL STATIC EQUILIBRIUM METHOD AND THE ADHESION AND SIDE FRICTION COEFFICIENT AS DETERMINED BY THE MODEL TESTS. THE INCREASE IN PILE CAPACITY DUE TO THE PLACEMENT OF HIGHWAY EMBANKMENT PRELOADS HAS ALSO BEEN CONSIDERED. /AUTHOR/

• Supplemental Notes:
  • 124 Pp, 49 FIG, 5 TAB, 80 FIG, 4 APP
• Corporate Authors:

  Tufts University

  /Civil Engineering Dept
  ,   United States 
• Authors:
  • Edgars, L
• Publication Date: 1970-3

Subject/Index Terms

• TRT Terms: Adhesion; Compaction; Design; Forecasting; Friction; Friction piles; Geometry; Mathematical models; Pile driving; Pile foundations; Pile groups; Silts; Spacing; Structural tests; Support piles; Theory
• Uncontrolled Terms: Capacity; Models
• Old TRIS Terms: Pile spacing; Pile tests
• Subject Areas: Bridges and other structures; Design; Geotechnology; Highways;

Filing Info

• Accession Number: 00209399
• Record Type: Publication
• Files: TRIS
• Created Date: Apr 18 1971 12:00AM