Soil Nail Coupler Projections Centering Grout Distribution
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Solution Overview
Problem
Current soil nail installations face challenges with mobile centralizers that can jam, are limited in size, and made of dissimilar metals, leading to corrosion issues and inefficient grout distribution, 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 distribution, made of the same metal as the soil nails to prevent corrosion, and featuring frangible joints for breaking away under excessive force.
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 can jam and are limited in size
Solution Approach 1:
The coupler is divided into a body portion and multiple removable projections. The projections can be detached from the body to prevent jamming during drilling operations, while still providing centering functionality when attached. This segmentation allows the centralizer to adapt to different drilling conditions without jamming.
Solution Approach 2:
The coupler transitions from a static mobile centralizer to a dynamic system where projections can be added or removed based on drilling conditions. The projections extend radially outward to provide centering when needed, but can be detached to avoid jamming in restrictive geological formations.
2Ease of manufacture
If dissimilar metals are used in coupler construction, then manufacturing flexibility is improved, but galvanic corrosion occurs
Solution Approach 1:
The coupler body and projections are made from the same metal or substantially similar metals, eliminating galvanic corrosion between dissimilar metals. This homogeneity in material composition prevents electrochemical reactions while still allowing for varied geometric configurations to meet manufacturing needs.
3Productivity
If grout is pumped at high pressure through hollow core soil nails, then grout distribution is improved, but grout may not adequately cover coupler surfaces
Solution Approach 1:
The coupler includes radially extending projections that increase the surface area in the radial dimension. This dimensional addition provides more surface area for grout adhesion without interfering with the axial flow of grout through the hollow core soil nail, thus maintaining grout distribution efficiency while improving coverage.
Solution Approach 2:
The coupler serves multiple functions: it connects soil nail sections, provides centering via projections, and enhances grout coverage through the same projection structure. The projections act as both mechanical connectors and grout retention features, eliminating the need for separate bearing plates.
4Force
If oversized bearing plates are used to distribute load, then load distribution is improved, but installation complexity and cost increase
Solution Approach 1:
The coupler merges the functions of connection, centering, and load distribution into a single component. The radially extending projections eliminate the need for separate bearing plates by providing sufficient surface area for load distribution directly at the coupler location, simplifying the overall system.
Solution Approach 2:
The coupler is designed as a multi-functional component that replaces multiple separate elements: it connects soil nail sections, provides centering during drilling, enhances grout coverage, and distributes structural loads. This consolidation reduces the number of components and simplifies installation procedures.
Data Source
AI summary
A coupler interconnects adjacent sections of soil nails to extend the lengths of the nails. The coupler includes 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 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 may include a plurality of ports or openings formed in the body of the coupler enabling injected material such as grout to be further mixed by the rotating action of the coupler during use. The invention further includes a soil nail assembly and a method for installing a soil nail assembly including couplers with projections.