GDS’ Triaxial Automated System (ELTAS) is fully integrated with existing equipment from LEMO’s laboratory. Hydraulic hoses and data cables supplied by GDS ensured full mobility of each triaxial cell and allowed use of existing load frames, load cells and transducers from other brands.
Specimen saturation became fully automated. GDSLAB software allowed the user to set a specific saturation ramp for a gradual increase in cell pressure and back pressure, otherwise impossible to achieve in non-automated triaxial systems, which can be intercalated with Skempton’s pore pressure coefficient B checks. Alternatively, an automatic saturation mode can be selected to reach a desired B value, through consecutive automatic pressure increments defined by the operator. Transition between every test stage can be done automatically according to the users criteria.
A data connection between load frame and a PC, running GDSLAB software (see Fig. 4), allows a user to set custom failure criteria, control axial displacement, strain rates and monitor all test parameters in real-time.
The additional demand on human resources was minimal, as active intervention of the operator during test execution was only needed for sample mounting, software test plan
selection/creation and to move the triaxial cell to load frame. The gain in response capacity initially estimated was later confirmed, with the average completion time for a full CU triaxial test performed with the ELTAS calculated at 11 calendar days, according to data from tests performed between 2010 and 2012. With earlier non-automated solutions, it was averaged 15 calendar days per test.
Fig 4. Load Frame connectivity.