True Triaxial Testing Equipment
RPS-100 Polyaxial / True Triaxial Testing System

The GCTS RPS-100 Polyaxial Testing System offers a precise analysis of the intermediate principal stress effect on rock engineering behavior and thus adequately describes the strength of rock under a general system.  Many add-ons can supplement this system to enhance and broaden testing.


  • 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 with 140 MPa (20,000 psi) maximum stress on a 100 mm cubical specimen.
  • Deformation sensors on each face to measure strains on the three principal directions.
  • Optional pore pressure intensifier to saturate the specimen and perform permeability tests.
  • Available P and S crystals on each loading face to measure ultrasonic velocities on every principal direction.
  • Available heating jacket to control temperatures from ambient to 150 C.
  • Optional hydraulic fracturing platens available to perform wellbore stability tests.
  • GCTS also offers stand-alone, large-scale Polyaxial systems built to customer specifications.

The GCTS RPS-100 Rock Polyaxial System can be used to study the intermediate principal stress effect on rock engineering behavior and describe adequately the strength of rock under a general system of Polyaxial compressive stresses. Syringe pressure intensifiers are used to apply σ1, σ2 and σ3 independently with measurement of volume/deformation change.


GCTS also offer semi-circular platens to test cylindrical specimens together with GCTS hydraulic fracturing fixtures and approximate the effects of anisotropic stress state on borehole stability. Even though the stress state applied with these semicircular loading jacks is not uniform, it is much easier to prepare and test cylindrical specimens.


Ultrasonic sensors can also be provided to study the effects anisotropic stress conditions on compression and shear wave velocities. Velocities for all three axes can easily be measured during Polyaxial tests with this option.


  • 100 mm x 100 mm x 100 mm maximum specimen size
  • 140 MPa stress capacity
  • 140 MPa confining pressure capacity


Please contact GCTS for full specifications.