Stress path triaxial and uniaxial automatic test system is designed to test various materials, from soft sandstone to high strength marbles.

The test system comprehends:

Servo-hydraulic control console for axial load application in conformity with the relevant Standards. Includes a dedicated software for triaxial testing which also controls the automatically determines the sample failure envelope.  The performs loading-unloading ramps and can also be used for load/stress/displacement/strain controlled testing on concrete, fiber reinforced concrete, shotcrete, etc.

Servo-hydraulic control console for confining pressure control into the Hoek cell (triaxial test only). It runs as a remotely controlled unit, fully operated by the Advantest Rock software. Includes 4 additional channels for strain / displacement transducers.

Advanced Software are linked to a single PC for data acquisition and results elaboration. The overall test information and readings are always available on the PC screen:

Hoek cell confining pressure

Axial load and sample strength

Sample deformation measured by strain gauges and external displacement transducers

Plus any additional load/strain/displacement readings from external transducers that may be useful for research purposes.

HOEK CELL: various models for different sample size are available: from EX type with dia. 21.46 mm up to HQ type for core with dia. 63.5 mm.

HIGH STIFFNESS COMPRESSION FRAME to be selected from the wide product range, conforming to the size of the sample and the expected strength. Due to the typical high strength and fragility of rocks we recommend high capacity test frame (4000kN or 5000kN capacity). 

Triaxial test is carried out automatically with multiple failure stages: from a single specimen it is possible to plot the entire failure envelope, Test procedure

Cell pressure is maintained constant and axial stress is increased

When the sample approximates maximum strength, the cell pressure is automatically increased up to a defined level

Cell pressure is again maintained constant and axial stress is increased

When the sample again approximates maximum strength, the cell pressure is further increased

Axial and horizontal stresses are increased hysotropically up to a defined level

The above procedure is automatically repeated several times

Cell pressure is reduced in steps and, for each step, the residual strength is measured

All the maximum peak loads are plotted against corresponding values of cell pressure building the complete failure path.

Maximum peak strength is reached and, in case of displacement control, the test is continued (softening phase).