Shielded tamper and method of use for making aggregate columns
View Patent ↗A tamper device includes a shaft for driving a tamper head. A tamper head is attached to the end of the shaft for tamping a lift of aggregate in a cavity formed in a ground surface. A shield extends upwardly a predetermined height from the tamper head an amount sufficient to prevent sidewalls of the cavity from failing and collapsing. Methods of constructing aggregate columns with thicker lifts are also disclosed.
1. A tamper device in combination with a preformed generally cylindrical elongate cavity, the device comprising:
a) a shaft for driving a tamper head;
b) a tamper head attached at the end of the shaft for tamping a lift of aggregate in the generally cylindrical elongate cavity formed in a ground surface, said tamper head having a generally flat, blunt bottom face; and
c) a shield extending upwardly a predetermined height from said tamper head an amount sufficient to prevent sidewalls of a cavity in soft soil in which the tamper device is used from failing and collapsing into the cavity.
2. The tamper device of claim 1 , wherein said tamper head further comprises a tapered surface extending circumferentially from said bottom face to an edge thereof.
3. The tamper device of claim 2 , wherein said tapered surface extends upwardly from the blunt bottom face at an angle of about 45 degrees.
4. The tamper device of claim 1 , wherein said shield is of a width wherein it is in abutment at a bottom edge thereof with the tamper head at a top surface about an edge thereof.
5. The tamper device of claim 4 , wherein said shield rests on the tamper head and has an opening for allowing passage of said shaft having said tamper head attached thereto.
6. The tamper device of claim 1 , wherein said predetermined height of said shield is in the range of about 3 to 5 feet.
7. The tamper device of claim 6 , wherein said width of the tamper head is in the range of about 12 to 36 inches.
8. The tamper device of claim 7 , wherein said tamper head is shaped substantially circular.
9. The tamper device of claim 8 , wherein said tamper head has a generally flat, blunt bottom face and a tapered surface extending from said bottom face to an edge thereof.
10. The tamper device of claim 1 , wherein said shield comprises a hollow cylinder.
11. The tamper device of claim 10 , wherein said hollow cylinder is filled with lightweight foam.
12. The tamper device of claim 1 , wherein said shield comprises synthetic belting wrapped around the shaft.
13. A method of constructing aggregate columns, comprising the steps of:
a) preforming an elongate cavity in a ground surface, said cavity having a generally uniform cross-sectional area;
b) placing a lift of aggregate into the cavity; and
c) tamping the lift with a tamper device having a tamper head attached at the end of a shaft, said tamper head having a generally flat, blunt bottom face, and having a shield extending upwardly a predetermined height from said tamper head an amount sufficient to prevent sidewalls of the cavity from failing and collapsing into the cavity.
14. The method of claim 13 , wherein said tamper head further comprises a tapered surface extending circumferentially from said bottom face to an edge thereof.
15. The method of claim 14 , wherein said tapered surface extends upwardly from the blunt bottom face at an angle of about 45 degrees.
16. The method of claim 13 , wherein said shield is of a width wherein it is in abutment at a bottom edge thereof with the tamper head at a top surface about an edge thereof.
17. The method of claim 16 , wherein said shield rests on the tamper head and has an opening for allowing passage of said shaft having said tamper head attached thereto.
18. The method of claim 13 , wherein said tamping is conducted by driving the tamper head with said shaft extending upwardly therefrom, said shield extending upwardly a predetermined height sufficient to prevent said side walls of the elongate cavity from failing and collapsing into the cavity during tamping operations, and said shield having an opening at the top allowing said shaft to pass therethrough to connect to said tamper head.
19. The method of claim 13 , wherein said predetermined height of said shield is in the range of about 3 to 5 feet.
20. The method of claim 19 , wherein said width of the tamper head is in the range of about 12 to 36 inches.
21. The method of claim 20 , wherein said tamper head is shaped substantially circular.
22. The method of claim 13 wherein the thickness of the lift of aggregate is approximately equal to two to three times the distance across the cavity.
23. The method of claim 13 , wherein said tamping is conducted in a cavity formed in soft soil.
24. The method of claim 13 , wherein said shield comprises a hollow cylinder.
25. The method of claim 24 , wherein said hollow cylinder is filled with lightweight foam.
26. The method of claim 13 , wherein said shield comprises synthetic belting wrapped around the shaft.