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for the civil engineering industry

Building better technology
for the civil engineering industry

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Triaxial Testing

The triaxial test is the most common test that can be performed on a ground surface to determine if that surface is suitable for building on. The test itself measures the level of shear stress that can be tolerated by a deformable solid – most commonly this is soil. Any triaxial test requires the use of a number of pieces of specialist equipment and software, all of which are supplied by VJ Tech.

Triaxial Test Equipment From VJ Tech

There are several variations of triaxial testing and all are covered Clisp Studio csTriax, csUNSAT and csSPATH software modules to BS, ASTM and AS standards. All triaxial test software that we provide is designed to allow automation of testing, minimizing the time that the operator is required to be present. This is a massive plus for consolidated triaxial tests, which can take a considerable amount of time.

Alongside our software modules, we also supply all of the necessary equipment to perform the triaxial test itself inlcuding triaxial load frames, triaxial cells, load transducers, displacement transducers, pressure transducers, data loggers, soil sample preparation tools and support stands for ease of use. The most common types of triaxial tests are consolidated drained (CD), consolidated undrained (CU) and unconsolidated undrained (UU). In consolidated triaxial tests, the sample is consolidated to a predefined effective pressure, then axial deformation is kept constant and pore pressures or volume changes are measured; this type of test may take considerably longer than an unconsolidated triaxial test, where the sample is compressed at a constant rate. All of these use broadly the same equipment but may have slightly different software requirements.


Consolidated Drained (CD), Consolidated Undrained (CU) & Unconsolidated Undrained (UU) Triaxial Testing

During Consolidated Drained (CD) triaxial testing, the sample is consolidated and sheared in compression with drainage. The rate of axial deformation is kept constant, i.e. is strain controlled. The idea is that the test allows the sample and the pore pressures to fully consolidate (i.e. adjust) to the surrounding stresses. The test may take a long time to allow the sample to adjust, in particular low permeability samples need a long time to drain and adjust strain to stress levels. In Consolidated Undrained (CU) triaxial testing, the sample is not allowed to drain. The shear characteristics are measured under undrained conditions and the sample is assumed to be fully saturated. During Unconsolidated Undrained (UU) triaxial testing, the sample is not allowed to drain. The sample is compressed at a constant rate (strain-controlled). See our Automated Triaxial Testing System and Automatic Triaxial Testing System (with separate data logger) for examples.

  

 

Unsaturated Triaxial Testing

During Unsaturated triaxial testing, the equipment must be capable of providing variable suctions whilst providing accurate measurement of soil volume change. See our Twin Cell Unsaturated Triaxial Testing System and Double Walled Cell Unsaturated Triaxial Testing System for examples.

 

Useful datasheets to download for further information

Triaxial Testing Datasheet DownloadTriSCAN Frames, Triaxial Testing Datasheet DownloadTriPLEX Frames, Triaxial Testing Datasheet Download Automatic Triaxial Testing, Triaxial Testing Datasheet Download Unsaturated Triaxial Testing, Triaxial Testing Datasheet Download Automatic Pressure Controllers, Triaxial Testing Datasheet Download Triaxial Cells

 

Applicable Geotechnical Standards:

  • ASTM D4767-11
  • ASTM D2850-03A
  • ASTM D2166/2166M-13
  • BS 1377:1990 (Parts 7 & 8)
  • AS 1289.6.4.1 (1998)
  • AS 1289.6.4.2 (1998)
  • GEOSPEC 3

Select the category of product you are interested in below to see available equipment options;