Self-centralizing soil nail and method of creating subsurface support

Abstract

A subsurface support is provided comprising a soil nail having an outer member and an inner member placed within the outer member. The soil nail includes features that maintain a uniform spaced relationship between the inner and outer members. The soil nail may be installed by drilling or launching through a launching device. The spaced relationship between the inner and outer members may be achieved by crimping the outer member, or by use of an insert installed between the inner and outer members. In other embodiments, the support is made of composite construction materials, and having a self-drilling capability. The soil nail has two primary members, namely, an outer threaded member, and an inner threaded member that is placed through the outer member The outer member is made from fiberglass, and a metallic drill bit is secured to a distal end of the soil nail. The inner member is preferably steel. The dual piece construction provides superior tensile and compressive strength, particularly for applications in which a coupler is used to join outer members to extend a length of the soil nail. A method is also provided to improve pull-out capacity by galvanizing the inner and outer members

What is claimed is: 
     
         1 . In combination, a soil nail and a spacer placed over the soil nail, comprising:
 a soil nail having proximal and distal ends; and   a spacer placed over said soil nail, said spacer having an inner portion with an opening through which said soil nail is received, and a plurality of radial projections connected to an outer surface of said inner portion, said radial projections spaced from one another around said outer surface and extending radially away from said inner portion.   
     
     
         2 . A soil nail comprising:
 a tubular outer member having a length, proximal and distal ends, an exterior surface, and an interior surface defining a central bore extending through said tubular outer member;   a crimped feature formed on at least one portion of said outer member, said crimped feature creating a smaller diameter area within said central bore of said outer member and creating at least one groove on said exterior surface of said outer member; and   an inner member placed longitudinally through said bore of said outer member and passing through said crimped feature.   
     
     
         3 . A soil nail, as claimed in  claim 2 , wherein:
 said crimped feature is formed on at least one pair of opposing sides of said outer member.   
     
     
         4 . A soil nail, as claimed in  claim 2 , wherein:
 said crimped feature is formed on two pair of opposing sides of said outer member.   
     
     
         5 . A soil nail, as claimed in  claim 2 , wherein:
 said crimped feature includes a plurality of crimped features, a first crimped feature formed at a distal end of said outer member, a second crimped feature formed at a proximal end of said outer member, and a third crimped feature formed between said proximal and distal ends of said outer member.   
     
     
         6 . A soil nail, as claimed in  claim 2 , further including:
 a self-drilling bit secured to a distal end of said outer member.   
     
     
         7 . A soil nail, as claimed in  claim 2 , wherein:
 said outer member includes a pair of outer members placed end to end, and a threaded coupler interconnecting abutting ends of the pair of outer members, thereby providing an extended length for a continuous outer member.   
     
     
         8 . A soil nail, as claimed in  claim 2 , wherein:
 said inner member extends beyond both said proximal and distal ends of said outer member.   
     
     
         9 . A soil nail, as claimed in  claim 2 , wherein:
 said inner member comprises a metallic cylindrical shaped bar.   
     
     
         10 . A soil nail, as claimed in  claim 2 , wherein:
 said inner member maintains a uniform concentric spaced relationship with an interior surface of said outer member.   
     
     
         11 . A method of installing a subsurface support comprising:
 providing a tubular outer member having a length, and proximal and distal ends;   creating crimped features on the outer member to narrow a diameter of an interior bore extending through the outer member;   emplacing the outer member into the ground;   filling the outer member with cementious material;   inserting an inner member through the bore of the outer member such that said inner member maintains a substantially uniform concentric relationship with an interior surface of said outer member by said crimped features.   
     
     
         12 . A soil nail, as claimed in  claim 10 , wherein:
 said inner member maintains a uniform concentric spaced relationship with an interior surface of said outer member.