Rock Mass Sealing Structure for High-Confining-Pressure Unloading Tests
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Solution Overview
Problem
Conventional triaxial tests for high-energy-storage rock masses face poor sealing effects and difficult sealing operations under high confining pressures, leading to hydraulic oil permeation and disturbance of the rock mass state post-test.
Innovation Solution
A pressure-bearing device comprising two pressure-bearing blocks, a waterproof casing pipe, and sealing rings with inclined surfaces and fastening elements, which are tightly pressed onto the casing pipe and pressure-bearing blocks to enhance sealing and facilitate operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional sealing methods (electrical adhesive tape winding or metal ring hooping) are used for sealing the rock mass and pressure head, then the sealing operation is simple, but the sealing effect is poor under high confining pressure
Solution Approach 1:
The sealing structure is divided into multiple components: a sealing ring made of rigid material, fastening elements for securing the sealing ring, and a waterproof casing pipe. This segmentation allows each component to perform its specific function effectively, with the sealing ring providing the actual seal, fastening elements ensuring secure attachment, and the casing pipe providing structural support and waterproofing.
Solution Approach 2:
The sealing ring acts as an intermediary element between the pressure-bearing blocks and the hydraulic system. It creates a reliable barrier that prevents hydraulic oil from permeating into the rock mass sample while allowing the high confining pressure to be effectively applied to the rock mass.
2Reliability
If an annular boss is used for sealing large-size rock mass, then the sealing reliability is enhanced, but the weight becomes large and sealing operation becomes difficult for testers with small strength
Solution Approach 1:
The sealing ring is made of a rigid material with optimized mechanical properties that provide sufficient strength for sealing under high confining pressure while maintaining a manageable weight. The use of rigid material with appropriate mechanical parameters allows the sealing component to be both reliable and operable by testers with small strength.
Solution Approach 2:
The sealing system uses a composite structure combining the rigid sealing ring, the waterproof casing pipe, and the fastening elements. This composite approach allows optimization of each component's material properties to achieve both high sealing reliability and operational convenience, avoiding the need for a single heavy annular boss structure.
3Stress or pressure
If high confining pressure is applied to the rock mass, then the stress state before excavation is simulated, but hydraulic oil may permeate into the rock mass sample
Solution Approach 1:
The rigid sealing ring and waterproof casing pipe convert the high confining pressure, which could potentially force hydraulic oil into the rock mass, into a beneficial force that presses the sealing ring against the pressure-bearing blocks, enhancing the seal. The sealing structure is designed to utilize the high pressure to improve sealing effectiveness rather than overcome it.
Solution Approach 2:
The sealing ring is designed as a dedicated sealing component that can be easily replaced if needed. Using a simple rigid material for the sealing ring provides effective sealing without complex mechanisms, and the sealing system can be quickly changed between tests to maintain sealing effectiveness.
4Duration of action of moving object
If the pressure head and oil cylinder are kept in contact during high-confining-pressure loading and unloading test, then the test can be completed, but the contact position is difficult to be instantly separated due to hydraulic oil film
Solution Approach 1:
The sealing ring and waterproof casing pipe create a barrier that extracts or isolates the hydraulic oil from the interface between the pressure head and the rock mass. This prevents the formation of a hydraulic oil film that would hinder separation, allowing the pressure head to be quickly removed from the oil cylinder after testing while maintaining sealing effectiveness during the test.
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 solution significantly improves the sealing effect and operation convenience, preventing hydraulic oil leakage and maintaining the rock mass state integrity during high-confining-pressure loading and unloading tests.
Implementation Method 1
fastening elements being further arranged between the sealing rings and the pressure-bearing blocks, the sealing ring being tightly pressed on the casing pipe and the pressure-bearing blocks through the fastening elements
Implementation Method 2
the abutting surfaces of the sealing rings, the casing pipe and the pressure-bearing blocks being inclined surfaces
Implementation Method 3
a casing pipe, the casing pipe being arranged outside the to-be-tested rock mass and the pressure-bearing blocks in a sleeving mode and being attached to the to-be-tested rock mass and the pressure-bearing blocks, and the casing pipe being made of a waterproof material
Data Source
AI summary
Disclosed is a pressure-bearing device for simulating an excavation unloading test of a high-energy-storage rock mass. The pressure-bearing device comprises pressure-bearing blocks, a casing pipe and sealing rings, wherein the two pressure-bearing blocks are respectively arranged at two ends of a to-be-tested rock mass; the casing pipe can be arranged outside the to-be-tested rock mass and the pressure-bearing blocks in a sleeving mode and is attached to the to-be-tested rock mass and the pressure-bearing blocks; and the sealing rings are arranged outside the pressure-bearing blocks and the casing pipe in a sleeving mode, so that the sealing rings can be tightly pressed on the casing pipe and the pressure-bearing blocks through fastening elements. Further disclosed is a sealing method for simulating an excavation unloading test of a high-energy-storage rock mass.