The invention discloses a triaxial geocomposite testing apparatus designed to simultaneously calibrate multiple pressure transducers. The apparatus comprises a fluid retaining section between a top portion and a base, featuring an inlet, an outlet, and multiple lateral openings. These openings allow the insertion of pressure transducers, which provide electrical signals during testing. A pedestal with recesses to hold earth pressure transducers is attachable to the base, enabling the simultaneous calibration of different-sized transducers. This setup ensures repeatability under various loading cycles and offers a significant improvement over traditional methods by eliminating the need for multiple pedestals and accommodating varying transducer dimensions.
Figure (1) Pictorial view of Universal Calibration Device
Calibration of pressure transducers is crucial for accurate measurement of stresses in construction materials like rocks, soil, and concrete. Traditional triaxial testing apparatuses can only calibrate one transducer at a time, requiring different pedestals for transducers of varying sizes, leading to increased costs and inefficiencies. Furthermore, these methods struggle with non-uniform pressure application due to fluid meniscus formation and face challenges in calibrating transducers with different dimensions.
- Simultaneous Calibration: Allows for the calibration of multiple transducers at once, unlike traditional methods that only handle one transducer at a time
- Versatility: Accommodates transducers of varying sizes without the need to replace pedestals, eliminating the major cost and time inefficiencies of previous methods
- Uniform Pressure Application: Overcomes the issue of non-uniform pressure due to fluid meniscus formation, ensuring more accurate calibration
- Cost-Effective: Reduces the need for multiple pedestals, significantly cutting down costs associated with calibration setups
- Enhanced Accuracy: The apparatus's design ensures uniform pressure distribution, improving the quality of calibration compared to traditional methods.
A standard triaxial cell, commonly found in soil mechanics laboratories, can be used to calibrate earth pressure transducers. For each specific transducer size, a matching pedestal is installed at the base, with the transducer securely fitted into a recess. The cell is then filled with fluid (e.g., water), and pressures within the transducer’s capacity are applied. As readings begin, a relationship between applied pressure and output (microstrain or microvolt) is established, enabling calculation of a calibration factor and preparation of a pressure-output chart for end-user reference. However, the major limitation of the triaxial cell is only one transducer can be calibrated at a time, and different sizes require separate pedestals, leading to increased costs. Moreover, the system is not suited for simultaneous calibration of multiple pore pressure transducers, which are critical for measuring pressures within particulate media.
The developed apparatus is capable of simultaneously calibrating multiple pressure transducers. It features a fluid-retaining section between a top portion and a base, which includes an inlet, an outlet, and several lateral openings. Fluid is introduced through the inlet and discharged via the outlet. Multiple pressure transducers can be inserted through the lateral openings to transmit electrical signals during testing. A pedestal, fixed to the base, includes one or more recesses on its top surface, each connected via an internal passageway to a side opening. Each recess is sized to securely hold an earth pressure transducer, with the recess diameter slightly larger than that of the transducer. Electrical cables run through the internal passageways and exit the base to connect the transducers to external pressure reading devices. A holding member within each recess ensures that the transducer is tightly secured, with its actuation surface aligned flush with the top of the holding member.
In recent years, efforts have been made to develop devices for in-soil calibration of earth pressure transducers (Watchman and Labuze 2011; Bishnoi et al., 2024). However, there is still limited research available on simultaneous fluid and in-soil calibration of pressure transducers with varying specifications.
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The innovative triaxial geocomposite testing apparatus enhances the reliability and accuracy of pressure transducers used in geomechanics. By reducing calibration time and costs, it supports infrastructure development and maintenance, leading to safer and more efficient construction practices.
- Geomechanical Testing: Suitable for testing rocks, soil, and concrete under triaxial conditions.
- Transducer Calibration: Enables accurate calibration of both earth pressure and pore pressure transducers.
- Civil Infrastructure Projects: Useful in evaluating material behavior for tunnels, dams, foundations, and retaining structures.
- Disaster-Resilient Design: Assists in calibrating instruments used for monitoring landslides, earthquakes, and structural health.
- Laboratory Research: Valuable tool in academic and industrial research on geomechanics and material behavior.
- Educational Use: Supports teaching and training in civil and geotechnical engineering labs.
- Quality Assurance: Beneficial for manufacturers of pressure transducers to ensure reliable product performance.
Geography of IP
Type of IP
223/MUM/2011
414990