Pretensioning Anchor Segmented Coupling Free Play
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Solution Overview
Problem
The existing technologies for installing prestressing anchors are labor-intensive due to the need for separate drilling and removal of drill pipes, and the use of cladding tubes often results in unintended force transfer and cement penetration, making it difficult to achieve a sufficient free play section for tensioning.
Innovation Solution
A prestressing anchor design where the cladding tube is rotated and forcibly coupled with the anchor rod during drilling, allowing for a free play section to be created within the cladding tube, enabling tensioning and load transfer without being tensioned itself, using a coupling mechanism that decouples in the longitudinal direction to prevent force transfer during tensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If cladding tubes are used to create a free play section in prestressing anchors, then the free play distance can be realized, but the cladding tube itself gets tensioned during the tensioning process and unintentionally dissipates forces into the subsurface
Solution Approach 1:
The cladding tube is segmented into multiple sections along its length, with coupling mechanisms positioned at specific intervals. These couplings connect the cladding tube to the anchor rod at discrete locations, creating a segmented force transfer system. This allows the cladding tube to provide lateral support and define the free play section while preventing unintended force dissipation along its entire length, as forces are transferred only at the coupling points to the anchor rod which then transfers to the adhesive section.
Solution Approach 2:
The coupling mechanism acts as an intermediary element between the cladding tube and the anchor rod. It selectively transfers forces from the cladding tube to the anchor rod at specific locations, mediating the force transfer process. This intermediary coupling allows the cladding tube to maintain its structural integrity and define the free play section without directly transferring forces along its entire length to the subsurface, thereby improving force transfer efficiency.
2Stability of the object's composition
If cladding tubes are used to create a free play section, then lateral support can be provided, but cement suspension penetrates into the cladding pipe making it difficult to provide sufficient free play section
Solution Approach 1:
The coupling mechanism extracts or removes the cladding tube from direct contact with the cement suspension in the free play section. By positioning the couplings at specific locations and connecting the cladding tube to the anchor rod only at these points, the design allows the cement suspension to be placed without penetrating into the cladding tube along its entire length. This extraction of the cladding tube from the cement-filled zone enables the creation of a sufficient free play section while maintaining borehole stability where the cladding tube is needed.
3Ease of operation
If standard drilling procedures are used with separate drill pipes, then boreholes can be drilled, but the process becomes labor-intensive and time-consuming
Solution Approach 1:
The invention merges the cladding tube with the anchor rod assembly into a single integrated unit that is installed together. The cladding tube is positioned on or alongside the anchor rod before insertion, and both components are inserted into the borehole simultaneously using the same drilling equipment. This merging eliminates the need for separate drilling operations with drill pipes, reducing labor intensity and installation time while maintaining the ability to create the required free play section.
Solution Approach 2:
The anchor rod assembly with the integrated cladding tube serves multiple functions simultaneously: it acts as both the drilling tool (replacing separate drill pipes) and the final prestressing anchor. The cladding tube provides both borehole stability during drilling and defines the free play section in the final installation. This multi-functionality eliminates the need for separate drill pipes and reduces the number of installation steps, thereby improving productivity.
Data Source
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AI summary
Prestressing anchor (1) for securing a geological formation (2), wherein the prestressing anchor (1) comprises an internally hollow anchor rod (3) and a drill bit (4) and a casing pipe (5) attached to a front end of the anchor rod (3), and the anchor rod (3) is surrounded by the casing pipe (5) in an area spaced away from the drill bit (4), wherein the casing pipe (5) can be forcibly coupled or forcibly coupled to the anchor rod (3) in at least one circumferential direction (7) around a longitudinal extension direction (8) of the anchor rod (3) for the purpose of rotating the casing pipe (5) with the anchor rod (3) during a drilling operation by means of at least one coupling (6) of the prestressing anchor (1).