Optical Fiber Layout for 3D Deep Rock Failure Localization
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Solution Overview
Problem
Existing distributed optical fiber monitoring systems for deep rock masses face challenges in effectively monitoring failure signals in complex geological environments, particularly in three-dimensional spaces, due to issues such as dispersed monitoring signals, difficulty in deployment, and low survivability, limiting their ability to accurately locate failure sources.
Innovation Solution
A distributed optical fiber monitoring system that deploys first and second optical fibers on chamber walls in axial and radial directions, utilizing peripheral segments and direction-changing transitions, along with integrated optical fiber sensors and a multi-channel sensing conditioner, to enable simultaneous monitoring of failure signals in three dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical fibers are deployed linearly along the axial direction of the tunnel, then the deployment is simple, but the monitoring coverage is limited to axial direction only and cannot achieve three-dimensional positioning
Solution Approach 1:
The patent introduces radial optical fiber segments perpendicular to the axial direction, transforming the monitoring system from one-dimensional (axial only) to two-dimensional (axial + radial). This allows the system to detect failure signals in multiple directions simultaneously, achieving three-dimensional positioning capability while maintaining relatively simple deployment procedures.
2Measurement precision
If optical fibers are bent extensively to couple with surrounding rock in deeply buried tunnel chambers, then the coupling effectiveness improves, but the survivability of the optical fiber greatly reduces
Solution Approach 1:
The optical fiber monitoring system is divided into multiple independent segments (axial segments and radial segments). Each segment can independently detect failure signals, and the segmentation allows the system to achieve effective coupling without requiring excessive bending of single continuous fibers, thereby improving both coupling effectiveness and fiber survivability.
3Adaptability or versatility
If multiple armored optical cables are deployed along top and side supporting rock masses, then the monitoring coverage increases, but the system complexity and difficulty in deployment increase
Solution Approach 1:
The patent combines axial optical fiber segments and radial optical fiber segments into an integrated monitoring system that shares common signal processing equipment and data analysis platforms. This merging approach increases monitoring coverage while avoiding the need for completely separate systems, thereby controlling overall system complexity.
4Measurement precision
If optical fibers are deployed in complex three-dimensional configurations to achieve comprehensive monitoring, then the monitoring precision improves, but the difficulty in deployment and maintenance increases
Solution Approach 1:
The patent implements a two-dimensional segmented optical fiber layout (axial + radial segments) that provides three-dimensional positioning capability. This approach achieves comprehensive monitoring and accurate failure source localization without requiring overly complex three-dimensional configurations, thereby maintaining relative ease of deployment and maintenance.
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
The system facilitates accurate three-dimensional positioning of failure sources by monitoring vibrations and acoustic emissions, allowing for real-time prediction and prevention of disasters like rock bursts, thereby minimizing casualties and property losses.
Implementation Method 1
monitors failure signals such as vibrations and acoustic emissions generated before and during occurrence of the rock mass failure
Data Source
AI summary
A distributed optical fiber monitoring system for failure monitoring of a deep rock mass is applied to an underground chamber and can simultaneously monitor failure signals in axial and radial directions of the underground chamber, facilitating three-dimensional positioning of a failure source. The distributed optical fiber monitoring system includes a first optical fiber and a second optical fiber. The first optical fiber is deployed on a chamber wall along the axial direction of the underground chamber to monitor the failure signal distributed along the axial direction of the underground chamber. The second optical fiber mainly includes a peripheral optical fiber segment and a direction-changing transition segment. The peripheral optical fiber segment is deployed on the chamber wall along a cross-sectional profile of the chamber wall to monitor the failure signal distributed along the radial direction of the underground chamber.