Pyramidal or conical shaped tamper heads and method of use for making rammed aggregate piers

• US 20070077128A1
• Filed: 09/28/2006
• Published: 04/05/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Geopier Foundation Company Incorporated (Tensar International Corporation)
• Original Assignee: Geopier Foundation Company Incorporated (Tensar International Corporation)
• Inventors: Wissmann, Kord
• Granted Patent: US 7,488,139 B2
• Time in Patent Office: Days
• US Class Current: 405/232
• CPC Class Codes: E02D 3/046 by tamping or vibrating, e.g. with auxiliary watering of the soil E02D3/026, E02D3/08 take precedence; generating or transmitting mechanical vibrations for performing mechanical work in general B06B; tamping or vibrating apparatus for working ballast or railways E01B27/00, for consolidating paving materials E01C19/30, for consolidating concrete in general E04G21/06
• CPC Class Codes: E02D 3/08 by inserting stones or lost bodies, e.g. compaction piles sand drains for soil compaction E02D3/10; stressing soil while forming foundations E02D27/28
• CPC Class Codes: E02D 3/123 and compacting the soil E02D3/126 takes precedence
• CPC Class Codes: E02D 5/44 with enlarged footing or enlargements at the bottom of the pile

Abstract

A tamper head having an elongated pyramidal or conical shape is used to construct rammed aggregate piers. The pyramidal or conical shape of the tamper head is more efficient at building up lateral earth pressure and provides for greater economy in the construction of the piers than available with existing methods that rely on tamper heads with flat bottoms and beveled sides.

Claims

1. A method of constructing aggregate piers comprising the steps of:

forming an elongated cavity in a ground surface, said cavity having a generally uniform cross-sectional area;

placing a lift of aggregate into the cavity with a lift thickness approximately equal to a distance across the cavity;

tamping the lift with a pyramidal or conically shaped tamper head having a top or base approximately equal to said cross-sectional area of the cavity to increase the lateral stresses in the sidewall of the hole; and

repeating the placing and tamping steps with successive lifts.

2. The method of claim 1 wherein the step of tamping includes using a tamper head having an inclination that varies from 45 degrees to 75 degrees from horizontal.

3. The method of claim 1 wherein the step of tamping includes using a tamper head that has a conical shape.

4. The method of claim 1 wherein the step of tamping includes using a tamper head that has a pyramidal shape.

5. The method of claim 1 wherein the elongated cavity is generally cylindrical and the step of tamping includes using a tamper head having a top cross-wise dimension approximately equal to a diameter of the cavity.

6. The method of claim 5 wherein said tamper head top dimension is no less than about 90% and no more than about 110% of the diameter of the cavity.

7. The method of claim 1 wherein the step of placing a lift of aggregate includes using aggregate having at least one of stone with fine materials, recycled concrete, recycled asphalt, slag, and cement treated base.

8. The method of claim 5 wherein the step of forming the cavity is by drilling.

9. The method of claim 1 wherein the step of forming the cavity is by penetrating and extracting an elongated tube or mandrel.

10. A tamper head for forming a rammed aggregate pier in a generally vertical hole in a ground surface, said hole having a generally circular cross-section, said tamper head comprising a generally pyramidal or conical body tapering toward a point at its lower end and having a cross-section at its upper end which is at least about 90% of said hole cross-section.

11. The tamper head of claim 10, further comprising a circular confinement plate mounted at an upper end of said pyramidal or conical body, said confinement plate having a diameter substantially equal to or greater than a longest dimension of an upper end of said pyramidal or conical body.

12. The tamper head of claim 10 wherein said lower end is blunted, having a blunted area no more than 20% of an area of its upper end.

13. The tamper head of claim 10, wherein said upper end of the generally pyramidal or conical body has a greatest dimension equal to between about 90% and about 110% of a diameter of said hole.

14. The tamper head of claim 10, wherein said generally pyramidal or conical body tapers at an angle to the horizontal of about 45 degrees to about 75 degrees.

15. The tamper head of claim 14, wherein said generally pyramidal or conical body tapers at an angle to the horizontal of about 60 degrees.

16. The tamper head of claim 10 wherein the tamper head has a conical shape.

17. The tamper head of claim 10 wherein the tamper head has a pyramidal shape.

18. The tamper head of claim 17 wherein said pyramidal shape is hexagonal in cross-section.

19. The system of claim 17 wherein said pyramidal shape is octagonal in cross-section.

20. The tamper head of claim 10 wherein the tamper head upper end has approximately the same diameter as the diameter of the cavity.