1. SPIRAL NAILS FOR REPAIRING BULGING FACE OF WELDED WIRE WALL _________________________________
ITD Project Development Conference
Boise, Idaho
April 2005
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By Tri Buu, P.E.
Geotechnical Engr.
Idaho Transportation Dept.

2. 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.

3. 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.

6. SPIRAL NAILS
BULGED WALL FACE

8. SPIRAL NAILS
SPIRAL NAILS

9. SPIRAL NAILS
NAIL END

10. SPIRAL NAILS
NAIL TIP

11. SPIRAL NAILS
NAIL SHAFT

12. SPIRAL NAILS
BEARING PLATE

13. SPIRAL NAILS
NAIL IN HAMMER

14. SPIRAL NAILS
POSITION NAIL FOR DRIVING

15. SPIRAL NAILS
DRIVING NAIL

16. SPIRAL NAILS
NAILED WALL FACE

17. SPIRAL NAILS
NAILED WALL FACE

18. SPIRAL NAILS
SEVERE BULGING WALL FACE

19. 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