Noncontact Electrodes for Shield Tunneling Real-Time Detection
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Solution Overview
Problem
The earth pressure balance shield tunneling machines face challenges in real-time detection due to the lack of detection space and interference from construction vibrations, making it difficult to use traditional geophysical methods, and existing contact electrode systems are prone to damage and low precision positioning.
Innovation Solution
A noncontact frequency-domain electrical real-time advanced detection system is implemented, using noncontact electrodes on the cutter head connected via a multi-way swivel joint, with a power supply and measurement unit, and a control unit for real-time data inversion and interpretation, allowing for three-dimensional imaging and automatic detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact electrodes are used for electrical detection in shield tunneling, then the detection can be performed in contact with the tunnel face, but the electrodes are easily damaged by construction vibrations and cannot work under the rotation of the cutter head
Solution Approach 1:
The patent replaces the mechanical contact electrode system with a non-contact capacitive coupling system. The power supply electrodes and measuring electrodes are positioned on the cutter head without direct contact to the tunnel face, using electromagnetic field coupling instead of physical contact. This eliminates the mechanical wear and damage issues while enabling operation during cutter head rotation.
2Difficulty of detecting and measuring
If the cutter head is retracted to create detection space, then geophysical detection can be performed, but the earth pressure balance of the tunnel face cannot be maintained
Solution Approach 1:
The patent merges the tunneling function and detection function into the same operational state. The cutter head performs both excavation and carries the electrical detection system, allowing detection to occur during normal tunneling operations without requiring retraction or separate detection phases, thus maintaining earth pressure balance while enabling detection.
Solution Approach 2:
The patent makes the detection system dynamic by positioning electrodes on the rotating cutter head. The system adapts to the rotating and advancing motion of the cutter head, performing detection continuously during tunneling operations rather than requiring static detection conditions or system retraction.
3Productivity
If BEAM method uses cutter as measuring electrode, then real-time detection is achieved, but the contact conduction results in high ground resistance and low positioning precision
Solution Approach 1:
The patent replaces the contact conduction method of BEAM with capacitive coupling. The measuring electrodes on the cutter head couple capacitively to the tunnel face without direct contact, eliminating the high ground resistance issue. This non-contact method provides better positioning precision while maintaining real-time detection capability during cutter head rotation.
4Productivity
If shield tunneling machine operates continuously, then construction efficiency is maintained, but no detection space is available for geophysical detection
Solution Approach 1:
The patent makes the detection system dynamic by integrating it with the moving and rotating cutter head. Detection occurs continuously during the tunneling process without requiring the machine to stop or create static detection space, thereby maintaining construction efficiency while enabling real-time geological detection.
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 system enables real-time advanced geological detection without shutting down the tunneling machine, improving detection efficiency and precision, and effectively avoids interference from metal objects, allowing for quick and accurate geological assessment in complex tunnel environments.
Implementation Method 1
current is emitted and received by capacitance coupling
Data Source
AI summary
A shield-carried noncontact frequency-domain electrical real-time advanced detection system and method are provided. Noncontact electrodes are installed on a cutter head of a shield tunneling machine, current is emitted and received using capacitance coupling, the electrodes are connected to a host via a multi-way swivel joint, measured data is inversed and interpreted in real time, and the prediction result is transmitted to a control system of the shield tunneling machine so as to provide a technical support for safety construction of the shield tunneling machine; the noncontact electrodes are installed on the shield cutter head. Real-time advanced detection of geology in front of a tunnel face can be realized in the tunneling process, so that the requirement for quick tunneling construction is met, and the efficiency of advanced geological detection of the shield tunneling machine is improved; and an electrode system is only installed on the cutter head.