Unsaturated Triaxial Test

The GCTS Unsaturated Soil Triaxial Systems (USTX Series) are electro-hydraulic or electro-pneumatic systems capable of performing unsaturated or partially-saturated triaxial tests on soil specimens. These systems include all required components for completely automated testing procedures, from simple triaxial tests to complete, multi-stage tests with stress path control.

These systems utilize double-walled triaxial cells to effectively eliminate compliance errors associated with single-walled cells when measuring the overall specimen volume changes. They include motorized ball valves to automatically recharge the pressure-volume intensifiers, flush air bubbles diffused through the ceramic stone, and reverse the direction of the volume change device that enables infinite volume measurement range as required by the on-going test. This system also includes components such as a de-airing water reservoir and vacuum pump to perform saturated or unsaturated soil triaxial tests.

Both hydraulic and pneumatic systems are available, depending on the required pressure control range, axial load requirements, and frequency requirements. Standard triaxial cells are available for specimens with diameters up to 150 mm, with larger sizes available upon request.

USTX Series


  • Direct control/measurement of pore water pressure (uw) at top/bottom of the specimen
  • Direct control/measurement of pore air pressure (ua) at the top of the test specimen
  • Performs static and dynamic tests
  • Sat./Unsat. Triaxial Shear with stress/strain path
  • Drying/wetting Soil Water Characteristic Curves (SWCC)
  • Hydraulic Conductivity Measurements with suction control
  • Saturated/Unsaturated Consolidation
  • Response to Wetting Test
  • Liquefaction
  • Resilient Modulus
  • Cyclic Strength
  • Frequencies up to 5 Hertz with significant amplitudes (larger with electro-hydraulic option)
  • Closed-loop digital servo control
  • Double cell wall construction for accurate overall volume change measurements
  • Easily exchangeable HAEV ceramic stones
  • Complete turn-key system

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Unsaturated Triaxial Test

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