Strain measurements techniques

Laboratory of Rock Deformation

Ground tensometry

The methodology has been developed of long-term measurements of ground deformation, applicable in mine subsidence areas, in landslide zones, the method being verified by 30 years' measurement data. The plane and spatial states of strain can be determined and the results are recorded automatically.

Strain measurement data vs time and the strain ellipses

Measurements of solid deformation under pressure

The methodology has been developed of using resistance strain gauges, attached to rock samples subjected to pressures up to 400 MPa. The transducer is applied in the shape of a helical steel spring encompassing the circumference of a cylindrical sample, in order to measure its transverse strains in the elastic or ductile state, under pressure up to 400 MPa.

The method is developed for measuring the changes in the cylindrical sample's circumference at several points of its generating line, using plastically deformable bands. The variations of the sample's shape can be determined in the tri-axial state of stress.

Differential strength limit as a function of pore pressure for the ambient pressure being the parameter. Fire-resistant shale, Nowa Ruda

Control of the bending moment applied to an axially compressed sample

By arranging at least three strain gauges on the sample's circumference, the moment can be determined as a function of applied loading. This measurement is of primary importance when controlling the loading uniformity.

Deformation of a cylindrical sample made from Czatkowice limestone is measured with three strain gauges (A, B, C) attached half way up its length, every 120 degrees and parallel to its axis, and with three strain gauges connected in series and fixed along the sample’s circumference (P). S - calculated mean axial deformation of the sample

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