Data from the in situ uniaxial compression experiments with CT-imaging:
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Metadata, describing the context of the experiments and the scientific
data made available in this repository.

0. Context of the data:
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The data set represents uniaxial compression test data on unsaturated soil columns of sand and glass beads
only kept together by capillary cohesion. In between incremental straining steps, the loading
is halted and CT-scans of the whole specimen volume are taken in order to investigate changes in capillarity
during compression and volume change. The experiments were run in 2018 at the University of Grenoble, using
the X-ray tomograph at Laboratoire 3SR. Both mechanical uniaxial compression test data and CT-data will be
published in the framework of this data set.

The experimental set-up used in the experiments is fully described in the following publication:

Milatz, M. (2019): Zur Anwendung von Einplatinen-Computern in der bodenmechanischen
Forschung und Lehre am Beispiel eines einaxialen Druckversuchs zur Untersuchung
teilgesättigter granularer Böden (On the application of single-board computers in soil
mechanical research and teaching using the example of an uniaxial compression test for
the investigation of unsaturated granular soils). In: Geotechnik 42 (1). (In German).
doi: 10.1002/gete.201800015.

Furthermore, the data accompanies another main publication (currently under review), focussing
on the analysis of CT-data. We will establish a link, as soon as this publication is available.

1. Mechanical data (measured with Raspberry Pi set-up presented in the paper):
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The following data files contain the measured and sorted stress-strain measurements
during the uniaxial compression tests with parallel CT-imaging.
Data can be opened with any text editor and visualized with the Python-script
Plot_the_data.py if desired. The visualization with the Python-script will produce
the png-images axial_stress_vs_axial_strain.png and volumetric_strain_vs_axial_strain.png
as output.

1.1 Data of all steps:
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Sand_001_stress_strain_results.txt
Sand_002_stress_strain_results.txt
Sand_003_stress_strain_results.txt

Glass_beads_001_stress_strain_results.txt
Glass_beads_002_stress_strain_results.txt
Glass_beads_003_stress_strain_results.txt

1.2 Data (points) after CT-scans:
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Sand_001_stress_strain_results_after_scans.txt
Sand_002_stress_strain_results_after_scans.txt
Sand_003_stress_strain_results_after_scans.txt

Glass_beads_001_stress_strain_results_after_scans.txt
Glass_beads_002_stress_strain_results_after_scans.txt
Glass_beads_003_stress_strain_results_after_scans.txt

2. CT-data (measured at Laboratoire 3SR, Grenoble):
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The following files represent the greyscale images obtained after reconstruction
of the raw CT-data using the reconstruction software X-Act of the CT-scanner
in Grenoble. Data (stored as 3D-tif-files) for every experimental step can be opened
with a tif-file reader, e. g. Fiji or ImageJ (https://imagej.net/Fiji).

2.1 Experiments on Sand:
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step_01 represents the initial state prior to uniaxial compression.

Sand_001_scan_01.tif ... Sand_001_scan_07.tif (6 compression steps)
Sand_002_scan_01.tif ... Sand_002_scan_07.tif (6 compression steps)
Sand_003_scan_01.tif ... Sand_003_scan_18.tif (15 compression steps, 2 scans at the end)

2.2 Experiments on Glass beads:
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step_01 represents the initial state prior to uniaxial compression.

Glass_beads_001_scan_01.tif ... Glass_beads_001_scan_07.tif (6 compression steps)
Glass_beads_002_scan_01.tif ... Glass_beads_002_scan_07.tif (6 compressoin steps)
Glass_beads_003_scan_01.tif ... Glass_beads_003_scan_18.tif (15 compression steps, 2 scans at the end)