Direct-shear experimental data on sedimentary gouge samples under high confining pressure and sliding velocity steps

This dataset contains raw experimental direct shear testing data as presented by "Ougier-Simonin, A., Castagna, A., Walker, R. J., & Benson, P. M. (2018). Frictional and mechanical behavior of simulated, sedimentary fault gouges. In AGU Fall Meeting Abstracts (Vol. 2018, pp. T11E-0212)". The data is provided in a .zip folder containing the files of 8 experiments that are accompanied by a README file for introduction. Files format is Microsoft Excel Worksheet (.xlsx) and data are tabulated. Each file contains the corresponding relevant sample’s details, and each column of data is clearly labelled, units included. For each experiment, time, axial force, axial displacement, axial stress, confining displacement, confining pressure, internal temperature, and axial delta P were recorded. Details of calculations for shear stress and coefficient of friction are also provided. Eight gouge (rock powder) samples of Monte Salici sandstone (Numidian Flysch, Appenninic-Maghrebian Chain; Sicily), ‘Comiso’ limestone (Ragusa Formation; Sicily) and Quaternary Clays (blue-grey clay in Fiumefreddo, Sicily) were tested in direct shear using sliding holders in triaxial compression at a confining pressure of 50 MPa. After 4 mm of axial (shear) displacement at 1 micron per second, variable rates of axial displacement were applied to induce velocity steps condition and measure rate-and-state parameters. Maximum displacement: ca. 9.8mm. All tests done at room temperature. The experiments were conducted by Drs A. Castagna and A. Ougier-Simonin using the MTS815 Rock Testing System in triaxial configuration and homemade sliding holders in the Rock Mechanics and Physics Laboratory of the British Geological Survey; both responsible for the collection and initial interpretation of the data. One test presented an issue on one of the signals recorded; the data are still shared for information purposes and the corresponding set of data is clearly named to indicate this fact.