Automatic Triaxial Testing System

It runs total and effective stress triaxial tests on soil specimens, with the cell pressure, back pressure and axial loading all under automatic control rather than set by hand during the test.

The system covers Consolidated Drained, Consolidated Undrained and Unconsolidated Undrained tests, stress path testing and slow cyclic testing at frequencies up to 0.1 Hz depending on amplitude.

Specimens up to 300 mm diameter and loads up to 250 kN are within range, with the smaller standard diameters from 35 mm upward covered by the matching cell and platen sets.

CD, CU and UU, plus stress path tests including K0 and anisotropic paths, and slow cyclic testing up to 0.1 Hz.

The CU test is the one most projects report against, and it is covered by ASTM D4767. The unconsolidated undrained test follows ASTM D2850.

Which of these your programme needs decides the pressure controller count and the transducer package, so it is worth settling before the quotation.

Specimen diameters up to 300 mm and axial loads up to 250 kN.

The upper end of that range is what separates this system from a standard laboratory triaxial frame: 300 mm specimens are used for coarse materials and for rockfill work where a 38 or 50 mm sample would not represent the grading.

Smaller specimens are run on the same frame with the appropriate cell and platen set: contact us with your specimen range.

Through the Pro Dual Automatic Pressure Controller, which controls and measures cell pressure, back pressure and volume change in one unit.

Working range is up to 3500 kPa. Volume measurement matters as much as pressure here, because saturation and consolidation are judged from volume change rather than from pressure alone.

Where a project needs pressures above that range, higher-pressure systems are configured to the application: request a quote.

Nine analogue channels and one digital input, logged through a built-in logger with 24-bit resolution at up to 5000 samples per second.

That channel count is what allows a full effective stress test to be instrumented properly: axial load, axial displacement, cell and back pressure, volume change and pore pressure without running out of inputs.

The sampling rate is well above what a static test needs, which is what makes the slow cyclic mode usable on the same hardware. Channels are consumed quickly once internal instrumentation is added: an internal submersible load cell, a mid-height pore pressure transducer and bender elements each take inputs of their own.

The system runs closed-loop control in displacement, load, speed and pressure modes, so the controlled variable is held rather than approximated.

PID settings are adjustable across the range of samples, which is the practical difference between testing a stiff overconsolidated clay and a soft normally consolidated one on the same machine.

An auto engage function applies the seating load, removing the part of the setup where operators most often disturb a specimen. The same control loop runs across the 10, 50, 100, 250 and 500 kN load ranges, so the behaviour does not change with frame size.

Yes. Advanced stress path control is one of the system's stated capabilities, including K0 and anisotropic consolidation.

Stress path testing is used where the field loading is not simple axial compression, for example under an embankment shoulder or beside an excavation, and the laboratory test has to follow that path.

It relies on independent control of cell and back pressure alongside axial load, which is why the pressure controller specification matters for this work. Anisotropic and K0 consolidation, and extension tests, also call for an internal submersible load cell rather than an external one, because the load has to be read inside the cell.

Cyclic loading at frequencies up to 0.1 Hz, with the achievable frequency depending on the amplitude.

It is used where a soil sees repeated loading rather than a single application, and where the question is how stiffness and pore pressure develop over cycles rather than at first failure.

For higher frequencies or larger strain work, a dedicated dynamic system is the right tool: contact us and we will say which fits.

Clisp Studio, connected over USB or Ethernet, with test setup, live monitoring and post-test analysis in one package.

Results are displayed in real time as a live data table and graph, and reports are generated and exported for further work on a PC.

The machine also runs standalone from its touchscreen display with data exported afterwards, which suits laboratories that do not want a PC beside every frame.

Multiple units are controlled from a single PC over LAN or through Ethernet and USB hub connections.

For a laboratory running triaxial tests in parallel, that is the difference between one operator supervising a bank of frames and one operator per frame.

Consolidation stages in particular run for days, so the value shows up in supervision rather than in test time. To scope a multi-frame layout, request a quote.

Soft limits are adjustable on every channel, and mechanical and sensor limits have automatic protection with auto-reverse from limit switch activation.

On a long-running consolidation stage that protection is what stands between an unattended overnight test and a damaged load cell.

The same soft limits also protect the specimen, by stopping a stage before the frame drives past the intended strain.

A manual setup needs an operator to adjust pressures and record readings through saturation, consolidation and shear. Each of those interventions is a chance for the record and the specimen to diverge.

Automation removes the routine adjustments and logs continuously, so the result carries its own history rather than a set of noted readings.

The rest of our soil mechanics range covers the simpler setups where full automation is not required.

The tests you report against, the specimen diameters you work with, and the pressure range your projects need.

Those three decide the frame capacity, the number of pressure controllers and the transducer package, which together make up most of the system cost.

Send them and we will configure it rather than quote a generic frame: request a quote.

A triaxial system is commissioned rather than simply delivered, because saturation and back pressure setup have to be verified on a real specimen before the laboratory relies on the results.

Training covers the software, the transducer calibration routine and the practical part that decides data quality: specimen preparation and membrane fitting.

To arrange it around your own soils, contact us.