True Triaxial System for Rocks
True Triaxial (Polyaxial) Test

The GCTS True Triaxial System was designed to perform extremely accurate true triaxial tests on rock specimens. This is done by allowing the stresses in all three dimensions to be individually controlled by the test operator, which allows for precise control of the stress path during the test. 


The True Triaxial System features:


  • Test cubical rock specimens up to a size of 300 mm x 300 mm x 600 mm (12”x12”x24”)
  • Independent control of σ1, σ2, σ3 (where σ1≠σ2≠σ3) or e1, e2, e3 or a combination of stress or strain control for each axis
  • Measures strains in all three orthogonal directions
  • Optional pore pressure control up to 140 MPa
  • Available ultrasonic sensors to measure P and S wave velocities under different stress states
  • Optional hydraulic fracturing platens available to perform wellbore stability tests
  • Stainless steel construction
  • Optional temperature control up to 200 °C


Small-scale testing can be performed inside a standard GCTS Triaxial Cell using the RPX-300 Polyaxial Fixture 

The GCTS Rock True Triaxial System was designed to analyze the effect of the intermediate principal stress on the strength of a rock specimen. This is done by allowing the test operator to control the stresses on all three faces of a cubical rock specimen. 


Options are available to allow for temperature control, ultrasonic velocity tests, and wellbore stability tests. 

Please contact GCTS for full specifications.