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Polyaxial Testing Systems

True-Triaxial Prüfanlagen

This unique experimental testing system is a customized solution used to study the behaviour of rock under various dimensional and compressive stress regimes (σ1 ≠ σ2 ≠ σ3). This fits to the research goals of geothermal energy researchers, hydrologists, petroleum reservoir engineers and researchers in the mining section, geophysics and geotechnical sectors. The systems are capable to test a wide range of materials from granite to mudstones and also for post-failure regime of high-strength brittle rocks.

Polyaxial rock testing systems are designed to induce stress on cubic samples via three independent controlled principal axes (σ1 ≠ σ2 ≠ σ3) up to 600 MPa. The sample chamber can house cubic samples up to 300 mm and has the option to be equipped with a temperature control up to 200 °C as well as a pore pressure device up to 210 MPa and the ability to have continuous acoustic emission recording, acoustic velocity and permeability (transient or steady state) measurements.

The complete system is fully automated and controlled by our flexible and programmable GEOsys Software. Various sensors, transducers, testing and experiment options are available.


  • High stiffness stand alone construction design
  • 6 hydraulic actuators for applying independent stresses (σ1 ≠ σ2 ≠ σ3) capacity up to 600 MPa
  • Cubical chamber for different sample sizes up to 300*300*300 mm
  • High pressure platens are combined with a friction reduction system.
  • 6 high precision displacement transducers to measure strains on each face
  • Dynamic high speed closed-loop control of load, displacement, position and volume or flow
  • Flexible controlling software for nearly unlimited test procedures of all polyaxial test applications
  • The system is capable of applying different stress paths or strain rates
  • Hydraulic power packs with high-quality noise protection, emergency functions
  • Digital setting of PID parameters for test parameter optimization and tuning
  • Real-time graphics software with zoom and freeze functions for printer output at any time
  • Expandable real-time high resolution data acquisition and closed-loop control system
  • Hydraulic fracturing test
  • Permeability test
  • Pore water pressure
  • Unsaturated conditions
  • System for measuring P- and S-wave in combination with acoustic emissions
  • Temperature controlling up to 200 °C

Type of load frame

Servo-hydraulic

Max. stress

Up to 600 MPa

Specimen shape

Cylindrical or cubic

Specimen size

From 25 mm cube core up to 300*300*300 mm

Pore fluid

Up to 150 MPa

Temperature control

Up to 200 °C

Permeability test

Steady state or transient

Stroke of actuator

100 mm

Customized set-up available upon request.