Coupler for soil nail and method of emplacing same
A coupler interconnects adjacent sections of soil nail members to extend a length for a soil nail to be installed. The coupler includes a plurality of projections extending from the exterior surface of the coupler. The projections serve multiple purposes. One purpose is to center the soil nail within a drilled hole. Another purpose is to provide mixing for selected amounts of drilled material to remain within the hole, and/or evacuation of drilled material to be removed from the hole. Another purpose is to create a drilled hole with varying diameters in response to different geological layers encountered during drilling. The coupler with projections therefore serves as a secondary drill bit implement. The size of the projections can be altered to selectively enlarge a desired portion of a drilled hole. The invention further includes a soil nail assembly and a method for installing a soil nail assembly including couplers with projections.
1. A coupler especially adapted for use in interconnecting of soil nails, said coupler comprising:
a body having a threaded opening formed through the body, said body having first and second opposite ends, a length and a longitudinal axis, said threaded opening extending along said longitudinal axis;
a plurality of projections mounted to an exterior surface of said body between said first and second ends, said projections each having a first end connected to said exterior surface and a second end extending radially outward from said longitudinal axis;
each projection having a selected length extending substantially parallel with said longitudinal axis, and said projections connected to said body along their respective lengths;
said projections being made from corresponding sections of solid metallic stock material; and
wherein said plurality of projections each have a frangible joint, each said frangible joint breaking at a predetermined stress or torque separating said plurality of projections from said body; and each said frangible joint being formed along a line extending with said longitudinal axis.
2. The coupler, as claimed in claim 1 , wherein:
said projections are substantially evenly spaced about a periphery of said body.
3. The coupler, as claimed in claim 1 , wherein:
said projections include at least two projections substantially evenly spaced about a periphery of said body.
4. The coupler, as claimed in claim 1 , wherein:
said projections include at least three projections substantially evenly spaced about a periphery of said body.
5. The coupler, as claimed in claim 1 , having at least one section that has a length that extends along at least one-half of the length of said body.
6. The coupler, as claimed in claim 5 , wherein: each section has a substantially same length.
7. The coupler, as claimed in claim 1 , wherein:
said coupler and said plurality of projections are integrally formed in a casting process.
8. The coupler, as claimed in claim 1 , wherein:
said coupler and said plurality of projections are integrally formed in a forging process.
9. The coupler, as claimed in claim 1 , wherein:
said projections are welded to said exterior surface of said body.
10. The coupler, as claimed in claim 1 , wherein:
at least one of said plurality of projections has a cross sectional shape in the form of a quadrilateral.
11. The coupler, as claimed in claim 1 , wherein:
at least one of said plurality of projections has a forward oriented edge especially adapted for cutting or drilling as said coupler is advanced into a hole in the ground.