In situ stress measurements
Hydraulic Fracturing (HF) – Hydraulic Jacking (HJ) – Hydraulic Test of Preexisting Fractures (HTPF)
The HF tests and they variants named HJ and HTPF have the goal to measure the natural stress in the rock masses, or the permeability of the fractures at high pressure levels.
They can be carried out in deep boreholes drilled from the topographic surface as in short boreholes drilled from underground
Doorstopper tests give accurate measures of the stress state existing in rock or concrete. They are performed in 76 mm diameter boreholes with maximum depth about 10 m.
Typical application scopes are tunnel linings, rock pillars or walls of mining stopes, beams of ordinary and prestressed concrete, retaining walls of reinforced concrete, the body of concrete dams.
Overcoring CSIRO Triaxial HI-CELL
The CSIRO tests measure with high accuracy the threedimensional stress tensor in a rock or concrete. The boreholes have 30 m maximum length.
Typical application scopes are: underground tunnels and chambers, quarry rock faces, the body of concrete dams.
The Flat Jack Test measures with accuracy the uniaxial surrfcial stress in rock or concrete, that is the normal stress component acting perpendiculary to the jack..
Typical application scopes are: underground tunnels, quarry excavation faces, underground ornamental stones quarries, the body of concrete dams.
A Shallow Overcoring Test measures measure the bidimensional surficial state of stress in a rock or concrete.
Typical scopes are tunnels, rock pillars, rock walls, concrete structures as tunnel linings, concrete walls, body of concrete dams.
Concrete Rebar Stress Measurement
The test is carried out on steel rebars of a reinforced concrete structure. It consists in measuring the strains when the bar is cutted.