Induction Coil Insulation for Anchor Removal
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Solution Overview
Problem
Existing methods for removing prestressed anchors from the subsoil are inefficient and unreliable, often resulting in abrupt failure and incomplete separation, which can compromise system safety and lead to premature loosening of the anchorage.
Innovation Solution
A method that uses an induction coil with a thermally insulated single-layer winding, supported by a rigid, electrically insulating and non-ferromagnetic tube, filled with a thermal insulation material to heat the tension members below their melting point, ensuring synchronized separation of the strands without the need for additional conductive tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical or thermal weakening is used to create breaking points, then the free anchor length can be expanded, but the tension members exhibit rigid behavior causing abrupt failure without previous stretching
Solution Approach 1:
The patent changes the physical state of the tension member by heating it to elevated temperatures (e.g., 200-400°C or higher), which fundamentally alters the material properties. At these temperatures, the steel strand becomes more ductile and exhibits plastic deformation behavior instead of rigid brittle failure, allowing gradual elongation and warning before separation occurs.
Solution Approach 2:
The patent utilizes the phase transition or property change of steel at elevated temperatures. The tension member transitions from a cold, rigid state to a hot, ductile state, enabling controlled deformation and energy absorption through plastic flow before final separation, thereby providing advance warning and preventing abrupt catastrophic failure.
2Productivity
If aluminothermic reaction mixture is used to heat or melt the tension members, then separation can be achieved, but uniform heating is difficult and complete separation does not always take place
Solution Approach 1:
The patent introduces a water-soluble polymer as an intermediary substance that is applied to the tension member before heating. This polymer layer acts as a heat transfer medium and protective coating, ensuring uniform heat distribution along the tension member. It prevents direct contact between the heating source and the steel strand, eliminating hot spots and ensuring consistent temperature distribution for complete and uniform separation.
Solution Approach 2:
The patent replaces the chemical aluminothermic reaction system with a controlled thermal heating system. Instead of using exothermic chemical reactions that are difficult to control and distribute uniformly, the invention uses external heating (e.g., induction heating, flame heating) combined with the water-soluble polymer to achieve uniform and controllable temperature distribution along the tension member.
3Reliability
If induction coil is placed between flat thermal insulation and asbestos hose, then the coil is protected against displacements, but the construction is complex and the coil can still be damaged when moved
Solution Approach 1:
The patent combines the thermal insulation function and the mechanical protection function into a single integrated water-soluble polymer layer. This polymer coating simultaneously provides thermal insulation to maintain heating efficiency and mechanical protection to prevent damage to the induction coil during positioning and movement, eliminating the need for separate insulation layers and protective housings.
Solution Approach 2:
The patent uses a flexible water-soluble polymer film or coating that can conform to the induction coil and the surrounding environment. This thin film layer provides adequate protection against displacements and damage while maintaining flexibility for easy installation and removal, replacing complex rigid insulation structures with a simple flexible protective layer.
4Use of energy by moving object
If the cable for energy supply runs between the strands, then power can be transmitted, but the cable can be easily damaged during prestressing
Solution Approach 1:
The patent extracts the energy supply cable from the hazardous zone between the tension members. Instead of routing the cable through the strand assembly where it would be subjected to compression and displacement forces, the cable is led externally along the outside of the tension member assembly, eliminating the risk of damage during prestressing operations while maintaining electrical connectivity to the induction coil.
5Temperature
If cavities between strands and collecting duct are not sealed, then water can penetrate and cool the strands, but sealing is required to maintain heating efficiency
Solution Approach 1:
The water-soluble polymer acts as an intermediary barrier that seals the cavities between the strands and the collecting duct. This polymer layer prevents water penetration while maintaining the thermal insulation needed for efficient heating. The polymer's water-soluble nature allows it to be easily applied and later removed without leaving residues, providing temporary sealing during the heating operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for reliable and controlled separation of tension members at temperatures below the melting point, preventing abrupt failure and ensuring complete removal of the anchor, while protecting the induction coil and preventing water ingress to maintain efficient heating.
Implementation Method 1
the strands can be heated in a controlled manner using an induction coil until they are severed
Implementation Method 2
heating the tension members beyond the Curie temperature to the melting point
Implementation Method 3
The separating device is equipped with an induction coil in the form of a single-layer winding made of thermally insulated copper wire
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
In the method for at least partially removing an armature (5) with at least one tension member (9), the tension member is heated for separation by means of an induction coil (16). During the heating process, the tension member (9) is pre-tensioned with a force that corresponds to at least 10%, preferably at least 25%, and particularly preferably at least 50% of the tensile strength at 0 degrees Celsius.