Soil Nail Coupler Projections for Centering and Bonding
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Solution Overview
Problem
Current soil nail installations face challenges with mobile centralizers that can become jammed, are limited in size, and may cause galvanic corrosion due to dissimilar metals, leading to inefficient centering and increased costs, especially in varying geological layers.
Innovation Solution
A coupler with radially extending projections that serve as a centralizer and drill bit, allowing for adjustable hole diameters and improved grout bonding, reducing the need for oversized bearing plates and minimizing corrosion risks by using the same metal type as the soil nails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mobile centralizers are used to center soil nails in drilled holes, then centering function is provided, but they become jammed and are limited in size
Solution Approach 1:
The patent combines the centralizer function with the coupler body by integrating radially extending projections directly into the coupler structure. This eliminates the need for separate mobile centralizer components that can become jammed, while maintaining the centering function through the fixed projections that guide the coupler within the drilled hole during installation.
2Ease of operation
If mobile centralizers are used, then centering is provided, but dissimilar metals cause galvanic corrosion
Solution Approach 1:
The patent ensures material homogeneity by constructing the coupler (including its integrated centralizer projections) from the same metal type as the soil nail sections. This eliminates galvanic corrosion risks that arise from using dissimilar metals between mobile centralizers and soil nail components, while maintaining structural integrity and corrosion resistance throughout the assembly.
3Strength
If oversized bearing plates are used to compensate for poor bond strength, then support capacity is increased, but installation complexity and costs increase
Solution Approach 1:
The patent creates preliminary grout bonding surfaces by forming enlarged diameter sections in the drilled hole using the coupler's radially extending projections before grout injection. This preliminary action enlarges the bond surface area between grout and geo-material, improving pullout resistance and reducing the need for oversized bearing plates to compensate for insufficient bond strength, thereby simplifying the overall installation.
4Reliability
If casings are used to support drilled holes in caving ground, then hole stability is improved, but installation speed decreases and costs increase
Solution Approach 1:
The patent creates preliminary stabilization by forming enlarged diameter sections in the drilled hole using the coupler's radially extending projections during the drilling process itself. This preliminary action provides immediate structural support in caving ground conditions without requiring separate casing installation, thereby maintaining hole stability while preserving installation speed and reducing costs.
Data Source
AI summary
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.