Unconfined compressive strength
UCS (also frequently named C0)Critical stress value at which a rock body fails brittlely under compresion. It may be determined directly via a uniaxial test under unconfined compressive conditions (σ1>>σ2=σ3=0 MPa) or by a series of triaxial tests (σ1>σ2=σ3≠0 MPa). In the latter case it is necessary to determine peak strength at several confining pressure stages (either via various single stage tests or via one multi stage experiment) and to draw a regression line through all peak strength data points to unravel the peak strength at 0 MPa as the UCS. This indirect way to determine UCS yields higher stress values than the direct measurements due to the fact that during confining pressure buildup in triaxial deformation tests microfractures are closing which will remain open during an unconfined compressive test. Consequently, only indirect UCS determination gives data for intact rock and only those data can be used for comparison with other data for the same rock type. Rock UCS values roughly range from 1 MPa (weakly consolidated sandstone) to 350 MPa (granite and basalt).
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The SCA 2025 in Hannover!
The SCA's Annual Symposium is being held in Germany for the first time. Gesteinslabor will be part of the exhibition in Hanover from 25 to 28 August 2025.
We would be pleased to welcome you at our booth 14.
Meet us at the GET 2025
27.-31. October 2025, Gesteinslabor will exhibit at the GET2025 in Rotterdam.
Find us at booth 605.
We are looking forward meeting you there!
We are pleased to be part of the Dutch subsurface research for geothermal heat SCAN.
Further information can be found on the official homepage:
https://scanaardwarmte.nl/english/
Gesteinslabor Dr. Eberhard Jahns is project and research partner within the HENRI (Hydrogen Energy Reservoir) project.
Main focus of us is the impact of H2 on the cap rock. Besides other parameters, we determine the capillary threshold pressure with different gases and gas mixtures.
First preliminary results could be presented at the 2nd HENRI conference.