Method and apparatus for constructing an underground barrier wall structure

• US 6,357,968 B1
• Filed: 01/12/2000
• Issued: 03/19/2002
• Est. Priority Date: 01/12/2000
• Status: Expired due to Term

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Dwyer, Brian P., Stewart, Willis E., Dwyer, Stephen F.
• Primary Examiner(s): Pezzuto, Robert E.
• Assistant Examiner(s): Addie, Raymond W
• Application Number:
  US09/482,303
• Time in Patent Office: 797 Days
• Field of Search: 405/128.15, 405/128.3, 405/125.45, 405/128.7, 405/128.5, 405/128.75, 405/129.1, 405/129.25, 405/129.3, 405/129.4, 405/129.45, 405/129.6, 405/129.65, 405/129.8, 122/69, 122/67, 122/66, 122/63, 122/64
• US Class Current: 405/269
• CPC Class Codes: E02D 2250/003 Injection of material
• CPC Class Codes: E02D 3/12 Consolidating by placing solidifying or pore-filling substances in the soil making piles E02D5/46; soil-conditioning or soil-stabilising materials C09K17/00; consolidation of ground around boreholes or wells E21B43/025
• CPC Class Codes: E02D 5/18 Bulkheads or similar walls made solely of concrete in situ moulds therefor E02D5/68; making foundation slots E02D17/13; sealing diaphragms other than those made of concrete E02D19/18

Abstract

A method and apparatus for constructing a underground barrier wall structure using a jet grout injector subassembly comprising a pair of primary nozzles and a plurality of secondary nozzles, the secondary nozzles having a smaller diameter than the primary nozzles, for injecting grout in directions other than the primary direction, which creates a barrier wall panel having a substantially uniform wall thickess. This invention addresses the problem of the weak “bow-tie” shape that is formed during conventional jet injection when using only a pair of primary nozzles. The improvement is accomplished by using at least four secondary nozzles, of smaller diameter, located on both sides of the primary nozzles. These additional secondary nozzles spray grout or permeable reactive materials in other directions optimized to fill in the thin regions of the bow-tie shape. The result is a panel with increased strength and substantially uniform wall thickness.

Claims

1. A jet grout injector subassembly, comprising:

a hollow cylinder comprising an open upper end, a closed lower end, a wall, and a longitudinal axis;

exactly six jet spray nozzles penetrating said wall of said cylinder, for spraying slurry from said hollow cylinder in a radially outward direction, said direction being oriented substantially perpendicular to said longitudinal axis;

wherein said six jet spray nozzles further comprise;

a pair of primary nozzles, having an inside nozzle diameter equal to D_p;

four secondary nozzles, having an inside nozzle diameter equal to D_s;

wherein D_p is larger than D_s; and

wherein said pair of primary nozzles further comprise;

a first primary nozzle that penetrates said wall at a circumferential angle equal to zero degrees; and

a second primary nozzle that penetrates said wall at a circumferential angle approximately equal to 180 degrees; and

wherein said four secondary nozzles further comprise;

a first secondary nozzle that penetrates said wall at a circumferential angle θ

approximately equal to θ

_offset;

a second secondary nozzle that penetrates said wall at a circumferential angle θ

approximately equal to −

θ

_offset;

a third secondary nozzle that penetrates said wall at a circumferential angle θ

approximately equal to 180+θ

_offset; and

a fourth secondary nozzle that penetrates said wall at a circumferential angle θ

approximately equal to 180−

θ

_offset; and

wherein said circumferential offset angle, θ

_offset, has a value between about 20 and 40 degrees.

2. The jet grout injector subassembly of claim 1, wherein said primary and secondary nozzles are replaceable.

3. The jet grout injector subassembly of claim 1, wherein said closed lower end has a pointed, conical shape.

4. The jet grout injector subassembly of claim 1, further comprising a drill bit assembly attached to said closed lower end.

5. The jet grout injector subassembly of claim 1, wherein said primary and secondary nozzles are located in close axial proximity to each other on said hollow cylinder.

6. The jet grout injector subassembly of claim 1, wherein said primary and secondary nozzles are located at substantially the same axial location on said hollow cylinder.

7. The jet grout injector subassembly of claim 1, wherein said circumferential offset angle, θ

_offset, is about 30 degrees.

8. A method of constructing a underground barrier wall comprising the steps of:

inserting the jet grout injector subassembly of claim 1 down a first hole in the ground;

rotating said jet grout injector subassembly about its longitudinal axis until a proper angular alignment of said subassembly relative to the surrounding ground is achieved;

supplying slurry under pressure to said jet grout injector subassembly; and

spraying said slurry radially outwards through a pair of primary nozzles in substantially diametrically opposed directions to a greater radial depth of penetration, and simultaneously spraying said slurry through a plurality of secondary nozzles in directions other than said diametrically opposed directions to a lessor radial depth of penetration, while simultaneously withdrawing, without rotation, said jet grout injector subassembly from said first hole;

whereby a first barrier wall panel is formed having a substantially uniform wall thickness and having two edges defined by said greater radial depth of penetration of slurry sprayed from said primary nozzles.

9. The method of claim 8, further comprising the steps of:

selecting a hole spacing distance equal to S_hole;

providing a second hole drilled into the ground, wherein said second hole is located at a distance S_hole from said first hole;

moving said jet grout injector subassembly from said first hole to said second hole;

inserting said jet grout injector subassembly down said second hole;

rotating said jet grout injector subassembly about its longitudinal axis until a proper angular alignment of said subassembly relative to said proper angular alignment of said subassembly in said first hole is achieved;

supplying slurry under pressure to said jet grout injector subassembly; and

spraying said slurry radially outwards through a pair of primary nozzles in substantially diametrically opposed directions to a greater radial depth of penetration, and simultaneously spraying said slurry through a plurality of secondary nozzles in directions other than said diametrically opposed directions to a lessor radial depth of penetration, while simultaneously withdrawing, without rotation, said jet grout injector subassembly from said first hole;

whereby a second barrier wall panel is formed having a substantially uniform wall thickness and having two edges defined by said greater radial depth of penetration of slurry sprayed from said primary nozzles; and

repeating all of these steps as many times as necessary to create an interconnected underground barrier wall structure having multiple panels;

wherein said step of selecting said hole spacing distance further comprises selecting said hole spacing distance so that one edge of said first barrier wall panel approximately touches an edge of said second barrier wall panel.

10. The method of claim 8, further comprising the step of using a drill bit assembly attached to a jet grout injector subassembly, wherein said drill bit assembly drills a hole in the ground while simultaneously carrying said attached jet grout injector assembly down said hole.

11. The method of claim 9, further comprising the step of using a drill bit assembly attached to a jet grout injector subassembly, wherein said drill bit assembly drills each hole in the ground while simultaneously carrying said attached jet grout injector assembly down said hole.

12. The method of claim 8, wherein said circumferential offset angle, θ

_offset, is about 30 degrees.

13. The method of claim 8, wherein said slurry comprises a substantially impermeable material.

14. The method of claim 13, wherein said substantially impermeable material comprises a cement-based grout mixture.

15. The method of claim 8, wherein said slurry comprises at least one permeable reactive material.

16. The method of claim 15, wherein said permeable reactive material is a material selected from the group consisting of:

active agents used in chemical precipitation treatment methods,

active agents used in oxidation-reduction reaction treatment methods,

active agents used in zero-valent metal dehalogenation treatment methods,

active agents used in biological degradation treatment methods,

active agents used in sorption of organics treatment methods, and

active agents used in sorption of inorganics treatment methods.

17. The method of claim 9, wherein the orientation of each adjacent panel is aligned substantially parallel to, and substantially in-line with, each other.

18. The method of claim 9, wherein the orientation of each adjacent panel is alternatively angled back and forth to create a folded, accordion-like pattern, wherein each panel intersects each adjoining panel.

19. The method of claim 8, wherein the orientation at least one portion of said first hole is angled less than 90 degrees with respect to the ground'"'"'s surface by using directional drilling techniques.

20. The method of claim 8, wherein the orientation of said first hole is substantially perpendicular to the ground'"'"'s surface.

21. The method of claim 9, wherein the orientation at least one portion of said second hole is angled less than 90 degrees with respect to the ground'"'"'s surface by using directional drilling techniques.

22. The method of claim 9, wherein the orientation of said second hole is substantially perpendicular to the ground'"'"'s surface.

23. A method of constructing an underground wall structure having a substantially uniform wall thickness, comprising:

inserting a jet grout injector subassembly into a hole in the ground;

supplying slurry under pressure to said subassembly;

spraying said slurry radially outwards into a cone-shaped primary zone;

filling-in the thin regions adjacent to the primary zone by simultaneously spraying said slurry radially outwards into a plurality of smaller, cone-shaped secondary zones located on both sides of the primary zone; and

withdrawing the subassembly from the hole during grout spraying.