DISCUSSION OF CAISSON CONSTRUCTION PROBLEMS AND CORRECTION IN CHICAGO

THIS PAPER IS IN KEEPING WITH DR TERZAGHI'S OFTEN REPEATED PLEA FOR THE PUBLICATION OF GOOD CASE HISTORIES FROM FOUNDATION PRACTICE. THE LONG-STANDING REPUTATION OF THE CHICAGO-WELL METHOD OF CONSTRUCTING FOUNDATIONS TO BEDROCK AT MODERATE DEPTHS BENEATH THE SURFACE , AND ITS WIDE USE IN OTHER AREAS, LENDS SPECIAL VALUE TO THE PAPER. IT IS FORTUNATE THAT THE AUTHORS HAVE BEEN ABLE TO SHARE SOME OF THE WIDE EXPERIENCE OF THEIR ORGANIZATIONS. SOME OF THE TERMINOLOGY IN THE PAPER IS, HOWEVER, A LITTLE PUZZLING. HARDPAN IS A TERM WHICH, ONE THOUGHT, HAD HAD BEEN ELIMINATED FROM THE SOIL MECHANICS LITERATURE FOR MANY YEARS, DESPITE ITS REPEATED USE BY NONTECHNICAL WORKERS. MANY WRITERS HAVE POINTED OUT ITS LIMITATIONS. THE WRITER IS CONCERNED WITH THE REPEATED USE OF THE EXPRESSION POURING CONCRETE INSTEAD OF PLACING CONCRETE. IF THE CONCRETE USED FOR CAISSON CONSTRUCTION IN CHICAGO IS REALLY POURED, THEN IT IS NATURAL THAT SOME TROUBLES HAVE BEEN EXPERIENCED. AND IF IT IS REALLY POURED WITH A FREE FALL AND PLACED ON SURFACES WITH STANDING WATER THEREON, THEN THE CONCRETE INDUSTRY'S WORTHWHILE CAMPAIGN TO ENCOURAGE BETTER CONCRETING PRACTICES WOULD APPEAR TO HAVE A GREAT DEAL OF PROGRESS TO MAKE. EVEN MORE SURPRISING IS THE STATEMENT THAT "ONE CAUSE OF DEFECTIVE CAISSONS IS BAD CONCRETE DELIVERED TO THE SITE." THIS IS A DISTURBING STATEMENT. LENGTHY REFLECTION ON THE PAPER SUGGESTS A FUNDAMENTAL QUESTION ABOUT THE PHILOSOPHY OF DESIGN THAT THE AUTHORS MIGHT BE WILLING TO DISCUSS. THE PAPER APPEARS TO BE BASED ON THE ASSUMPTION THAT FAILURES WITH CAISSON FOUNDATIONS IN CHICAGO ARE INEVITABLE. SINCE THE USUAL DIAMETER OF FOUNDATION CAISSONS IN CHICAGO PERMITS VISUAL INSPECTION BEFORE CONCRETING AND REASONABLE INSPECTION DURING CONCRETING---CERTAINLY MORE THAN CAN BE GIVEN TO THE CONCRETING OF A HEAVILY REINFORCED CONCRETE COLUMN ABOVE GROUND---WHY SHOULD THIS ANTICIPATION OF FAILURE BE SO OBVIOUSLY A GOVERNING FEATURE OF DESIGN? ONE HAS YET TO HEAR OF CORE BORINGS BEING USED TO CHECK THE SOUNDNESS OF MAJOR COLUMNS OF REINFORED CONCRETE BUILDINGS. WHAT IS IT THAT MAKES THIS SO ACCEPTED A PRACTICE WITH CAISSONS IN CHICAGO? SURELY A BASIC PRECEPT OF CIVIL ENGINEERING IS THAT DESIGN SHOULD PRODUCE A STRUCTURE, OR COMPONENT, THAT WILL SAFELY AND ECONOMICALLY CARRY ALL DESIGNED LOADS WITH NO POSSIBILITY OF FAILURE OTHER THAN THAT CAUSED BY A MAJOR CATASTROPHE? IF THE AUTHORS COULD GIVE STATISTICS AS TO THE NUMBER OF SUCH FAILURES AS THEY DESCRIBE IN DISCUSSING THIS BASIC QUESTION, THE OVERALL PICTURE MIGHT THEN BE SOMEWHAT CLEARER. /DISCUSSER/

  • Supplemental Notes:
    • Vol 97, No SM 9, PP 1347-1348, 1 REF
  • Authors:
    • Legget, R F
  • Publication Date: 1971-9

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Filing Info

  • Accession Number: 00233215
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 20 1971 12:00AM