The dataset presented here contains the results of mechanical testing of two granular materials (quartz sand and glass micro beads) that are commonly used in analogue tectonic experiments. The data were acquired using a ring-shear tester RST-01.pc [Schulze, 1994]. Tests were performed at different normal loads ranging from 125 Pa to 4000 Pa and with eight to ten repetitions per normal load and material. The parameters measured are: rotation velocity, shear stress, normal load and sample dilation, all as a function of time. A detailed analysis and interpretation of the data can be found in the main article of [Ritter et al., 2016].The data were measured in the ring-shear tester RST-01.pc [Schulze, 1994, see below] at GFZ Potsdam’s analogue laboratory for tectonic modelling. All samples have been prepared and measured by the same person. Preparation was by sifting from a constant height of 30 cm into the shear cell. Tests were performed at different normal loads ranging from 125 Pa to 4000 Pa and with eight to ten repetitions per normal load and material. For normal loads below 500 Pa, the samples were pre-loaded by shortly increasing the normal load to 500 Pa and then resetting it to the desired value prior to the onset of deformation. This pre-loading was carried out for technical reasons. Preliminary tests at a normal load of 300 Pa have shown that this does not affect the strength.The data are presented as shear curves in tab-separated text files. The file names consist of (in this order) material, normal load and a running number. Each file contains one shear curve and consists of a header describing the individual measurements followed by a table with one column per parameter (read more in the dataset description pdf).References:Schulze, D. (1994) Entwicklung und Anwendung eines neuartigen Ringschergerätes, Aufbereitungstechnik, 35(10), 524–535.
This dataset provides friction data from ring-shear tests on feldspar sand FS900S used for the simulation of brittle behaviour in crust- and lithosphere-scale analogue experiments at the Tectonic Modelling Laboratory of the University of Bern (Zwaan et al. in prep; Richetti et al. in prep). The materials have been characterized by means of internal friction parameters as a remote service by the Helmholtz Laboratory for Tectonic Modelling (HelTec) at the GFZ German Research Centre for Geosciences in Potsdam (Germany). According to our analysis both materials show a Mohr-Coulomb behaviour characterized by a linear failure envelope. Peak, dynamic and reactivation friction coefficients of the feldspar sand are μP = 0.65, μD = 0.57, and μR = 0.62, respectively, and the Cohesion of the feldspar sand is in the order of 5-20 Pa. An insignificant rate-weakening of less than 1% per ten-fold rate change is registered for the feldspar sand. Granular healing is also minor.