SPIRAL NAILS FOR REPAIRING BULGING FACE OF

WELDED WIRE WALL

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ITD Project Development Conference

Boise, Idaho

April 2005

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By Tri Buu, P.E.

Geotechnical Engr.

Idaho Transportation Dept.

SPIRAL NAILS

MICA CREEK BRIDGE WAS CONSTRUCTED IN 2002, ON US-95, SOUTH OF C.D’.ALENE, IDAHO

HILFIKER WELDED WIRE WALLS WERE USED TO CONTAIN THE APPROACH EMBANKMENTS ON BOTH ENDS OF THE BRIDGE.

SOON AFTER THE WALLS WERE CONSTRUCTED, BULGING FACE PROBLEMS DEVELOPED IN SEVERAL LOCATIONS NEAR THE TOP OF SOUTHWEST AND NORTHEAST WINGWALLS, WHICH HAVE A 3 FEET HIGHT GABION WALL SITTING ON TOP OF THEM. IT IS BELIEVED THAT THE PROBLEMS WERE CAUSED BY THE EXCESSIVE VERTICAL SPACING OF WALL BACKFILL REINFORCEMENTS (OVER 3 FEET, WHILE TYPICAL SPACING IS 2 FEET)

THE WALL MANUFACTURER, HILFIKER, WAS CONTACTED REGARDING THESE FACING PROBLEMS AND THEY SUGGESTEDTHAT SPIRAL NAILS BE USED TO CORRECT THE PROBLEM.

SPIRAL NAILS

SPIRAL NAIL IS A HOLLOW NAIL HAVING A SPIRAL SHAPE SHAFT, ABOUT 10 FEET LONG WITH A 5” SQUARE PLATE AT THE END.

THE NAILS WERE DRIVEN THROUGH THE WELDED WIRE WALL FACES AND INTO WALL BACKFILL WITH A HYDRAULIC IMPACT HAMMER. THE HAMMER WAS MOUNTED AT THE BOTTOM OF AN EXCAVATOR’S BUCKET.

THE NAILS WERE DRIVEN IN BETWEEN TWO LAYERS OF WALL BACKFILL REINFORCEMENTS, AT A DOWNWARD ANGLE OF ABOUT 5 DEGREES. NAIL SPACINGS WERE ABOUT 3 FEET. THEY WERE DRIVEN ABOUT 2 TO 3 INCHES INTO THE WALL FACE. COULD BE DRIVEN DEEPER BUT STOPPED TO AVOID POTENTIAL DAMAGES TO WIRES AT WALL FACE. IT TOOK ABOUT 1.5 MINUTES TO DRIVE IN THE 10 FEET LONG NAIL.

MAIN APPLICATION OF NAILS IS TO KEEP THE BULGING PROBLEM FROM GETTING WORSE.

SPIRAL NAILS

BULGED WALL FACE

SPIRAL NAILS

SPIRAL NAILS

SPIRAL NAILS

NAIL END

SPIRAL NAILS

NAIL TIP

SPIRAL NAILS

NAIL SHAFT

SPIRAL NAILS

BEARING PLATE

SPIRAL NAILS

NAIL IN HAMMER

SPIRAL NAILS

POSITION NAIL FOR DRIVING

SPIRAL NAILS

DRIVING NAIL

SPIRAL NAILS

NAILED WALL FACE

SPIRAL NAILS

NAILED WALL FACE

SPIRAL NAILS

SEVERE BULGING WALL FACE

SPIRAL NAILS

DON’T KNOW ????? PULL OUT CAPACITY OF NAIL HOW LONG THE NAILS WILL LAST

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NEXT IS A VIDEO OF THE NAIL INSTALLATION