In-Situ Rock Strength Testing Device for Bolt Supported Roadways
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Solution Overview
Problem
Current in-situ testing methods for rock strength, such as hydraulic fracturing, are inaccurate and disruptive under soft rock conditions, making it difficult to design effective support systems for underground engineering, especially in coal mines with weak lithology.
Innovation Solution
An in-situ test device comprising a fixing mechanism, loading mechanism, measuring mechanism, and control system that allows for non-invasive stress and strain measurements using infrared ranging and wireless pressure monitoring, eliminating the need for drilling and water injection, and enabling adaptable installation on bolt-supported roadways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydraulic fracturing method is used for in-situ testing, then measurement precision is improved under hard rock conditions, but surrounding rock is greatly disturbed under soft rock conditions
Solution Approach 1:
The testing device is divided into multiple independent modules: fixing mechanism, loading mechanism, measuring mechanism, and control system. Each module performs a specific function, allowing the system to achieve accurate measurements without requiring disruptive procedures like drilling or water injection.
Solution Approach 2:
The device uses an intermediary pressing die that applies controlled loading to the surrounding rock through the bolt support system. This intermediary approach allows measurement of rock strength parameters without direct contact with or intrusion into the rock mass, thereby avoiding disturbance.
2Adaptability or versatility
If drilling and water injection processes are used, then in-situ testing can be performed, but original rock properties are greatly interfered with
Solution Approach 1:
The invention extracts the essential measurement function from the disruptive drilling and water injection processes. By using the existing bolt support system as the testing platform and applying loading through the pressing die, the device achieves in-situ testing without removing rock samples or injecting fluids that would alter rock properties.
Solution Approach 2:
The patent replaces the hydraulic fracturing mechanical system with a controlled compression loading system. Instead of using high-pressure water to fracture the rock, the device applies mechanical compression through the loading cylinder and pressing die, measuring rock strength parameters through controlled deformation rather than fracture.
3Measurement precision
If indoor testing with rock sampling is used, then test results accuracy is improved for hard surrounding rock, but applicability deteriorates for soft surrounding rock
Solution Approach 1:
The device utilizes the existing bolt support system and surrounding rock mass as part of the testing apparatus itself. The bolt, pressing die, and loading mechanism work together with the rock mass to perform the test, eliminating the need to extract and transport rock samples to a laboratory. This self-service approach enables testing in-situ for both hard and soft rock conditions.
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 device provides accurate and rapid measurements of surrounding rock strength with minimal disturbance, improving support design and stability analysis, particularly in soft rock conditions, and is easy to install and disassemble, reducing test errors and increasing applicability.
Implementation Method 1
the measuring mechanism includes an infrared ranging unit and a wireless pressure monitoring unit
Implementation Method 2
the wireless pressure monitoring unit is arranged on the loading cylinder, monitoring data of the measuring mechanism is transmitted to the control system
Implementation Method 3
the loading mechanism includes a hydraulic pump, a plunger pump, a loading cylinder
Implementation Method 4
the hydraulic pump is connected with the plunger pump through a coupling, the plunger pump is connected with a hydraulic oil tank
Data Source
AI summary
An in-situ test device and method for surrounding rock strength of bolt supported roadway is provided. The test device includes a fixing mechanism, a loading mechanism, a measuring mechanism and a control system. The loading mechanism includes a hydraulic pump and a plunger pump, the hydraulic pump drives the plunger pump to work and controls the lifting speed of the loading cylinder; the measuring mechanism includes an infrared ranging unit and a wireless pressure monitoring unit; the control system controls the work of the loading mechanism and processes the monitoring data. The test device is directly installed in the roadway and fixed with the bolt. The device is loaded after leveling, the device is disassembled after the monitoring data are obtained, and the in-situ test for the surrounding rock strength of the bolt supported roadway is completed. The steps are simple and adaptable.