Low Stress Triaxial Testing Device with Floating Piston
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low stress triaxial tests on soft soils like sand, silt, and saturated soft soil face challenges in sample preparation due to the soft nature of the samples, leading to inaccurate results. Additionally, the tests are highly susceptible to external factors such as rubber film constraints, self-weights, and friction, which can significantly impact the accuracy of the results.
Innovation Solution
A device for low stress triaxial testing is designed to minimize external disturbances by using a super-light clay membrane, lubricating oil, silicone grease, and a confining pressure control system. The device includes a pressure chamber, a test platform, a base, a servo motor, and various sensors and valves to ensure accurate and stable measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rubber membrane is used for sample containment, then the sample can be held during testing, but the rubber membrane causes wrinkling and buckling that induce initial strains and affect measurement accuracy
Solution Approach 1:
The patent removes the traditional rubber membrane from the test system and replaces it with a rigid circular ring constraint structure. This extraction eliminates the harmful wrinkling and buckling effects of flexible membranes while maintaining the necessary sample containment function through the rigid ring and base plate assembly.
Solution Approach 2:
The patent uses a thin circular ring made of rigid material instead of flexible rubber membrane. This rigid thin structure provides stable geometric constraints without the flexibility that causes deformation, thereby eliminating initial strain induction while maintaining sample containment.
2Ease of manufacture
If conventional sample preparation methods are used for soft soils, then samples can be obtained, but the soft nature of samples makes them easy to disturb during preparation, resulting in inaccurate test results
Solution Approach 1:
The patent employs a floating piston design where the piston weight is counterbalanced by buoyant force from water. This allows the piston to apply minimal disturbance to the soft soil sample during consolidation, enabling easy sample preparation without compromising sample integrity.
Solution Approach 2:
The patent uses water as a consolidation medium instead of air or other gases. The hydraulic system provides gentle, uniform consolidation pressure through the water-saturated porous stone and filter paper assembly, minimizing sample disturbance during the preparation process while maintaining ease of operation.
3Adaptability or versatility
If small confining pressure is applied for low stress testing, then the test conditions match low stress environments, but the results become extremely susceptible to external factors such as friction and self-weights
Solution Approach 1:
The patent replaces traditional mechanical friction-based constraints with a rigid ring geometric constraint system. This substitution eliminates friction between the sample and containment structure, allowing accurate measurement of small confining pressures without the results being contaminated by frictional effects.
Solution Approach 2:
The patent uses porous stone and filter paper assemblies that allow water to pass through while providing uniform distribution of confining pressure. This porous structure minimizes localized stress concentrations and friction effects, enabling precise measurement of low stress conditions.
4Productivity
If traditional triaxial test device is used, then standard testing can be performed, but factors such as piston self-weights, top cap self-weights, and end constraints create significant disturbances
Solution Approach 1:
The patent employs a floating piston design where the piston's self-weight is counterbalanced by buoyant force from the water medium. This eliminates the harmful effect of piston weight on the soft soil sample during testing, while maintaining standard triaxial testing capability.
Solution Approach 2:
The patent introduces water as an intermediary medium between the loading system and the soft soil sample. The water-saturated porous stone and filter paper assemblies act as intermediaries that distribute loads uniformly and eliminate direct contact friction, reducing external disturbances while maintaining standard testing functionality.
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 effectively reduces disturbances during sample preparation and testing, ensuring accurate and authentic measurement results. The use of a super-light clay membrane and lubricating oil minimizes sample disturbance, while the confining pressure control system provides stable and precise confining pressure, enhancing the reliability of the low stress triaxial test results.
Implementation Method 1
a base, configured to place a sample coated with a super-light clay membrane
Implementation Method 2
the lubricating oil applied to the outer shell and the inner shell of the sampling cylinder can ensure that the disturbance to the super-light clay membrane and the sample is reduced during a sample extraction process
Implementation Method 3
The silicone grease applied on surfaces of the base and the top cap can reduce impact of friction on the low stress triaxial test
Implementation Method 4
the confining pressure control system provides stable and precise confining pressure, enhancing the reliability of the low stress triaxial test results
Implementation Method 5
the axial force sensor is disposed on the loading piston
Implementation Method 6
the pore pressure sensor is disposed on the first pipeline
Implementation Method 7
the deformation measuring device is disposed on the second pipeline
Data Source
AI summary
A device for a low stress triaxial test includes a test platform; a pressure chamber disposed on the test platform; a base disposed on the pressure chamber and fixed to the test platform; a support disposed on the test platform; a servo motor disposed on the support; a loading piston connected to the servo motor and penetrating into the pressure chamber; an axial force sensor disposed on the loading piston; a top cap detachably connected to the loading piston and covering the sample; a first pipeline connected to the base and passing through the test platform to connect with a measurement system; a second pipeline connected to the pressure chamber and passing through the test platform to connect with a confining pressure control system; and a third pipeline connected to the first pipeline and the top cap. The device can ensure the accuracy and authenticity of test results.