BRAVA - Brittel-Rock investigAtionVersatile Apparatus

BRAVA - Brittel-Rock investigAtionVersatile Apparatus

TEES designed and manufactured for INGV the prototype rock deformation biaxial apparatus to examine the physical properties of brittle rocks.

The apparatus is installed in the HP-HT lab at the INGV in Rome.
The machine (about 6Tons weight) consists of a stainless steel pressure vessel with internal diameter of 40 cm, equipped with 2 hydraulic pistons, horizontal for normal stress and vertical for shear stress.

Two big steel portholes make the positioning of the holders and rock samples assembly very easy.

The vessel was designed to be and maintain an internal pressure up to 850bar. Five holes on the pressure vessel allow to connect up to 100 sensors close the sample when the portholes are closed.

One potentiometer with resolution of 0.15 mm is installed on each piston for measuring the displacement. High sensitive LVDT sensors are fixed on the  horizontal and vertical pistons to validate the sliding and the deformation of the sample during the experiments.

Pistons are driven by two very sensitive voltage control signals servo-valve and can work independently in load or displacement feedback control, obtaining a sliding velocity into the range 0.1 μm/s - 2 cm/s between the samples.

Two load cells with a dynamic load ranging up to 150 Tons and 30Kg of sensitivity are mounted onto each vertical and horizontal pistons.

The apparatus has other three hydraulic pistons positioned on the kart, that operate as fluid pressure intensifier and they are controlled by three proportional valves.

Two of these pistons intensifier  are dedicated for the pore fluid circulation into each sample rock.

The third piston intensifier is used to keep the confining pressure of oil around to the sample.