Unsaturated Triaxial System

VJ Tech’s Unsaturated Triaxial System is used for triaxial testing in unsaturated (or partially saturated) soils. The Double Wall Triaxial Cell design ensures precision in measuring soil volume changes throughout the testing procedure by separating the acrylic Inner from the Outer Cells.

The Unsaturated Triaxial System is equipped with air bleed screws on both cells for efficient de-airing. The system features 6 valves for air/water control and can withstand confining pressures up to 2000 kPa. Base Pedestals, including those with encapsulated Bender Elements, feature an interchangeable ceramic disc (HAED) with the ability to separate the air and the water phases up to a specified air pressure. Top caps bring, also, an HAED allowing a double water drainage and reducing the testing time by 4 times (compared to single drainage). The Cell base incorporates 5 exit ports, accommodating On-Sample Transducers, Bender Elements, or a Mid-Pore Pressure Transducer for accurate geotechnical data.

Suction is controlled inside the sample through the axis translation technique, utilising a hydraulic and a pneumatic Automatic Pressure Controllers (APC) to impose pore air and pore water pressures. Sample volume changes are determined through a Volume-Change device and confining pressure is applied using a hydraulic APC.

csUNSAT software allows the automated control of all pressures and stresses when a test is performed. Available stages include Equalisation, Consolidation, Stress Paths (q – p – suction), Shear.

  • Suction control using the Axis-Translation technique
  • Electromechanical frame (TriSCAN series) for the control of deviator stress
  • Automatic Pressure Controllers for the control of the Confining, Pore Water and Pore Air pressures
  • Reliable monitoring of the moisture content change via a hydraulic APC
  • Monitoring of the total sample volume change through a Volume Change device
  • Ability to control Net Stress applied to the sample
  • Equalisation, isotropic consolidation, stress paths (Net Stress – Deviator Stress – Suction) and failure stages are available
  • Built-in logger allowing high speed sensor data conversion (24 bit, up to 5000 samples/s)
  • Closed Loop control for Displacement, Load, Speed mode and Pressure.
  • Flexibility to adjust PID for a variety of samples, ranging from stiff to soft soils
Load Range
50kN, 100kN, 250kN
Available Sample Sizes
50mm, 70mm, 100mm
Maximum Cell Pressure
2000 kPa
Maximum Pore Water Pressure
1000 kPa
Maximum Pore Air Pressure
1500 kPa
Maximum applied suction
1000 kPa
Electrical Requirement
220-240VAC 50/60Hz 1ph
PC Connectivity
USB or Ethernet
Test Performed
  • Static Unsaturated Triaxial Testing
Porous Stones

Variety of sizes available in Bauxite stone or Sintered Metal for improved durability during high loads

Filter Paper

Available in a variety of sizes

De-aired water system

De-aired water tank (19 litre capacity) availability in hard anodised finish, or stainless steel for better durability. Vacuum pump is required; sold separately.

APC Water & Air Distribution Panel

Assists users fill/empty their Pressure Controllers, Triaxial Cells and other pressure chambers. A variety of sizes panels are available to connect multiple devices. Can be supplied with or without a mechanical pressure gauge; which can act as an independent reference point.

High Air Entry discs

Available in a variety of HAE Values, typically; 1 Bar, 3 Bar, 5 Bar, 15 Bar

Upgrade Options *
Bender Element Testing
Soil Water Characteristic Curve (SWCC)
Triaxial Tests (UU, CU, CD)
Stress Path
Advanced Triaxial and Cyclic Tests
*Upgrade options will require additional hardware. Contact us for more information.

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