The Semi-Automatic configuration for determining the elastic modulus and strength characteristics of rock specimens is based on automatic compression machine for axial loading and manually-operated pump for confining pressure. The 2 systems are operated independently and the failure envelope is obtained by a series of individual tests (single - stage) with manual adjustment of the axial load and manual application of the confining pressure at different levels. It performs either uniaxial or triaxial tests under load/stress control (no strain).

TEST PROCEDURE:

Cell pressure is maintained constant and axial stress is constantly increased by the pressure-compensated proportional valve up to specimen failure (single-stage);

Axial and confining stresses are independently increased isotopically up to a defined level: Axial load is controlled by a special pressure-compensated proportional valve; confining pressure is controlled by the manual pump with pressure maintainer;

Strain values are acquired by data logger.

The procedure above is repeated N times using new specimens at various confining pressure levels. Combining these results it is possible to plot the failure envelope with N points using the dedicated MS Excel spreadsheet.

Technical Specifications:

Lateral pressure system

The unit comprises a hand pump connected to a special oil reservoir, a precision pressure gauge, a pressure maintainer and a flexible hose 3 m long with a 90° quick release coupling. The Low friction manual pressure maintainer is used for maintaining constant the desired lateral pressure in the Hoek triaxial cells. 

Max working pressure: 40 MPa

Weight approx.: 15 kg.