Download: Pump actuated triaxial systems features.pdf
Four systems are available in the range: TRILAB, PREPEAK, ROCLAB, and AVS700. These pressure-actuated triaxial systems are engineered to apply and independently control three principal stress components—axial load, confining pressure, and pore pressure—on cylindrical rock specimens mounted inside a high-pressure triaxial cell. The rock core is jacketed, positioned between the lower pedestal and upper loading platen, and sealed to allow fully independent regulation of external confining pressure and internal pore-fluid pressure. The cell is filled with hydraulic oil and connected to electro-mechanical pumps capable of generating the axial, confining and pore pressures required for advanced rock mechanics testing. Depending on the instrumentation fitted, the systems can be configured for multiple experimental protocols, including stress–strain tests, ultrasonic velocity measurements, acoustic emission (AE) monitoring, electrical resistivity tests, hydraulic fracturing experiments and permeability tests.
The axial pressure pump delivers hydraulic fluid to the axial chamber above the cell’s loading piston, generating the compressive force applied along the specimen’s longitudinal axis. Axial loading can be servo-controlled in load, displacement, or constant strain-rate mode. A high-precision load cell continuously records the force transmitted through the specimen, ensuring accurate determination of deviatoric stress across all deformation stages, including elastic loading, yielding, peak stress, and post-peak behavior.
Confining pressure is applied using an electro-mechanical pump connected to the cell chamber. By pressurizing the cell fluid, it imposes an isotropic radial stress around the specimen. This pump can operate in constant-pressure or constant-displacement modes depending on the testing requirements, with continuous feedback control ensuring stable confinement during loading, unloading, creep, or relaxation stages.
Pore pressure is controlled by a separate pump connected to the specimen’s drainage ports. This pump regulates the internal fluid pressure of the sample and can run in constant-pressure, constant-flow, or constant-volume-change modes to simulate a wide range of hydro-mechanical boundary conditions, including drained, partially drained, and undrained scenarios.
For tests performed at elevated temperature, the triaxial cell can be equipped with an external heating jacket. The temperature control system maintains uniform heating of the specimen, enabling thermo-hydro-mechanical coupling experiments representative of reservoir environments.
Instrumentation is integral to the system’s performance. Axial deformation is recorded by internal LVDTs designed to operate under high-pressure conditions, while radial deformation is measured via diametral extensometers mounted around the sample. These sensors allow precise determination of volumetric strain, Poisson-ratio evolution, and time-dependent deformation throughout the loading sequence.
Through coordinated control of axial, confining, and pore-pressure pumps plus deformation and force sensors, the systems can reproduce many stress paths—from triaxial compression to hydrostatic loading, creep, relaxation, shear-compaction, and complex failure. Running pumps in constant-pressure, constant-strain, or constant-load modes offers the flexibility needed for standard lab tests and advanced rock-mechanics research.