Weak Fiber Grating Sensor for Deep Roadway Strain Monitoring
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Solution Overview
Problem
Current deformation monitoring methods for surrounding rock in deep coal mine roadways are inaccurate and costly, failing to effectively monitor the complex deformation processes due to their operational complexity and high equipment costs.
Innovation Solution
A weak optical fibre grating sensor system with a quasi-distributed sensing capability, utilizing a weak optical fibre grating array with peak reflectivity less than 1% to accurately measure strain and temperature changes in the surrounding rock, providing a strong data basis for stability control through embedded optical fibre gratings and a monitoring system that determines appropriate support measures based on deformation ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional deformation monitoring methods are used for surrounding rock in deep coal mine roadways, then monitoring coverage is provided, but monitoring accuracy is low and equipment cost is high
Solution Approach 1:
The patent replaces conventional mechanical deformation monitoring equipment with optical fiber grating sensors. The optical fiber grating sensors use optical principles instead of mechanical mechanisms to detect strain and temperature changes in surrounding rock, thereby reducing operational complexity while improving monitoring accuracy through distributed sensing capabilities along the optical fiber length.
Solution Approach 2:
The patent uses optical fiber grating sensors that create optical copies of deformation information through Bragg wavelength shifts. The gratings reflect specific wavelengths of light that change in response to strain, effectively copying the mechanical deformation state into optical domain for accurate measurement without complex mechanical contact.
2Measurement precision
If conventional monitoring equipment is deployed, then deformation data is collected, but equipment cost is high
Solution Approach 1:
The optical fiber grating sensor serves multiple functions simultaneously: it monitors both strain and temperature, provides distributed sensing along its entire length rather than at discrete points, and can be embedded within the surrounding rock structure. This multi-functionality reduces the need for multiple separate monitoring systems, thereby lowering overall equipment cost while maintaining high monitoring accuracy.
Solution Approach 2:
The patent merges multiple sensing functions into a single optical fiber grating sensor system. The optical fiber simultaneously carries strain sensing gratings and temperature sensing capabilities, combining what would traditionally require separate instruments into one integrated system, thus reducing equipment cost and simplifying deployment.
3Area of stationary object
If traditional sensors are used, then point measurements are obtained, but spatial coverage is limited
Solution Approach 1:
The optical fiber is segmented into multiple sensing sections along its length, with optical fiber gratings distributed at different positions. Each grating acts as an independent sensing point, and by combining data from all segments, the system achieves both wide spatial coverage and high measurement precision through the distributed nature of the sensing network.
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 enables precise monitoring of surrounding rock deformation, providing a robust data foundation for stability control, allowing for timely and effective support interventions, thereby enhancing safety and production efficiency in deep coal mine roadways.
Implementation Method 1
a part of the optical wave having a wavelength satisfying the Bragg grating condition being reflected back
Data Source
AI summary
The present application provides an optical fibre grating sensor and a strain monitoring method and system for a surrounding rock of a deep roadway, which are used for monitoring deformation of the surrounding rock of the deep roadway and are provided with a weak optical fibre grating array large-range strain sensor, which can accurately monitor the strain of the surrounding rock of the deep roadway. The optical fibre grating sensor comprises an optical fibre, the optical fibre comprises an optical fibre core and a plurality of optical fibre gratings inscribed on the optical fibre core, the optical fibre grating is a weak optical fibre grating with a peak reflectivity lower than 1%, and the plurality of optical fibre gratings perform unit discretization on the whole piece of the optical fibre so as to realize quasi-distributed sensing.