ANCHORS FOR UNSTABLE GROUND

GROUND ANCHORS CAN PROVIDE ONE OF THE MOST RELIABLE SOLUTIONS TO CONSTRUCTION IN UNSTABLE GROUND. DRILLING DOWN TO ANCHOR INTO SOUND STRATA ALLOWS A SERIES OF STRUCTURES OF KNOWN LOAD-BEARING CAPACITY TO BE PLACED AND TESTED, ALLOWING POSITIVE DESIGN PARAMETERS TO BE SET AND MAINTAINED. GUESSWORK ON SOIL STABILITY IS ELIMINATED, AND THE ECONOMIES ARE THOROUGHLY FAVORABLE COMPARED WITH BORED PILING, DEEP EXCAVATION, OR MASS CONCRETE. ANCHORAGE IS EQUALLY SUITABLE FOR PERMANENT OR TEMPORARY STRUCTURES. MADE UP GROUND ON AN EMBANKMENT, CUTTING OR ABUTMENT CAN BE TIED BACK INTO SOLID STRATA, OR ANCHORS CAN BE USED IN PLACE OF STRUTS TO RETAIN SHEET PILE WALLS ONLY DURING THE CONSTRUCTION PERIOD. CONSIDERABLE ECONOMICS ARE POSSIBLE IF, FOR INSTANCE, ANCHORS ARE COMBINED WITH SHEET PILE OR DIAPHRAGM WALLS, WHEN A SERIES CAN BE USED TO ASSURE LONG-TERM STABILITY DESPITE THE PRESENCE OF SLIP PLANES BELOW THE WALL. A MAJOR ADVANTAGE OF TEMPORARY ANCHORS IS A COMPLETELY CLEAR SITE, FREE OF PROPS AND TIMBER, WHICH ALLOWS EXCAVATION TO BE CARRIED ON RIGHT UP TO THE PILE FACE, THE SIZE OF AN EXCAVATION CAN BE MINIMIZED, AND THE TECHNIQUE IS PARTICULARLY VALUABLE ON TIGHT AREA SITES. AT THE OPPOSITE END OF THE SCALE, ANCHORAGE CAN BE USED AS A FOUNDATION METHOD IN ITS OWN RIGHT. AT ORFORD NESS, SUFFOLK, THE LARGEST ANCHORAGE CONTRACT OF ITS TYPE IN THE WORLD WAS COMPLETED TO PROVIDE LOAD CARRYING POINTS FOR ANTENNA GUYS. MORE THAN 750 ANCHORS WERE PLACED IN EXCEPTIONALLY DIFFICULT STRATA, RANGING FROM WET SAND TO VERY SOFT CLAY, WITH A BASIC DESIGN REQUIREMENT THAT MOVEMENT AT THE GUY/ ANCHOR JUNCTION SHOULD NOT EXCEED 1 IN. IN 10 YEARS. DESPITE THE GROUND CONDITIONS, TEST ANCHORS ACCEPTED LOADS UP TO 105 TONS IN SAND, AND 95 TONS IN CLAY. PARTICULARLY RIGOROUS INSPECTION AND TESTING WAS APPLIED TO EVERY PRODUCTION ANCHOR, AND OVER THE ENTIRE SITE ONLY FOUR WOULD NOT CARRY THE FULL TEST LOAD. RECENT DEVELOPMENTS IN THE THEORY AND PRACTICE OF GROUND ANCHORAGE SUGGEST THAT IT CAN BE USED CONSIDERABLY MORE WIDELY THAN AT PRESENT, AND IS CAPABLE OF GIVING SIGNIFICANT SAVINGS IN CONSTRUCTION TIME AND COST. THE ABILITY TO TEST EACH UNIT SEPARATELY IS PARTICULARLY VALUABLE IN POOR GROUND CONDITIONS, AND ALLOWS SPECIFICATIONS TO BE MET WITHOUT ALLOWING OVER-GENEROUS AND EXPENSIVE SAFETY MARGINS AS AN INSURANCE AGAINST FUTURE MOVEMENTS. /AUTHOR/

  • Corporate Authors:

    Universal Anchorage Co Ltd

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  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00236251
  • Record Type: Publication
  • Source Agency: Civil Eng & Public Works Review /UK
  • Files: TRIS
  • Created Date: Jan 31 1972 12:00AM