RST Evaluation - Scripts for analysing shear experiments from the Schulze RST.pc01 ring shear tester

Rudolf, Martin; Warsitzka, Michael

doi:10.5880/gfz.4.1.2021.001

Cited by 3 publications

(6 citation statements)

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“…Most of them have been subjected to standard ring shear tests to determine their time-independent friction parameters (friction coefficient and cohesion) and rate-dependent (velocity strengthening or weakening) friction parameters. To have consistent evaluation parameters, we re-picked and re-analysed the existing datasets with the newest software RST-Evaluation (Rudolf and Warsitzka, 2021), which is the current standard for ring shear tests in our laboratory. New materials that were not in our test database were tested with the standard ring shear test outlined in Sect.…”

Section: Methodsmentioning

confidence: 99%

“…2.2. For this study, we tested all samples with the slide-hold-slide procedure developed in Rudolf et al (2021), which is outlined in Sect. 2.4.…”

Section: Methodsmentioning

confidence: 99%

“…The testing procedure follows standardised procedures for sample preparation (Lohrmann et al, 2003;Klinkmüller et al, 2016), testing procedure (Lohrmann et al, 2003;Ritter et al, 2016a) and data analysis (Rosenau et al, 2018a;Rudolf et al, 2021). All samples are first oven dried to remove excess humidity and then stored in the air-conditioned laboratory for several days to equilibrate with ambient laboratory conditions of T = 25 • C and ≈ 50 % humidity.…”

Section: Ring Shear Tester Setupmentioning

confidence: 99%

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Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

2023

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Abstract. Analogue models are often used to model long-term geological processes such as mountain building or basin inversion. Most of these models use granular materials such as sand or glass beads to simulate the brittle behaviour of the crust. In granular material, deformation is localised in shear bands, which act as an analogue to natural fault zones and detachments. Shear bands, also known as faults, are permanent anomalies in the granular package and are often reactivated during a test run. This is due to their lower strength compared to the undeformed material. When the fault movement stops, time-dependent healing immediately begins to increase the strength of the fault. Faults that have been inactive for a long time therefore have a higher strength than younger faults. This time-dependent healing, also called time consolidation, can therefore affect the structure of an analogue model as the strength of the fault changes over time. Time consolidation is a well-known mechanism in granular mechanics, but it is poorly described for analogue materials and on the timescales of typical analogue models. In this study, we estimate the healing rate of different analogue materials and evaluate the impact on the reactivation potential of analogue faults. We find that healing rates are generally less than 3 % per 10-fold increase in holding time, which is comparable to natural fault zones. We qualitatively compare the frictional properties of the materials with grain characteristics and find a weak correlation of healing rates with sphericity and friction with an average quality score. Accordingly, in models where there are predefined faults or reactivation is forced by blocks, the stability range of the fault angles that can be reactivated can decrease by up to 7∘ over the duration of 12 h. The stress required to reactivate an existing fault can double in the same time, which can favour the development of new faults. In a basin inversion scenario, normal faults cannot be inverted because of the strong misorientation, so time consolidation plays little additional role for such models.

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Section: Methodsmentioning

confidence: 99%

“…2.2. For this study, we tested all samples with the slide-hold-slide procedure developed in Rudolf et al (2021), which is outlined in Sect. 2.4.…”

Section: Methodsmentioning

confidence: 99%

Section: Ring Shear Tester Setupmentioning

confidence: 99%

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Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

2023

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“…The testing procedure follows standardized procedures for sample preparation (Lohrmann et al, 2003;Klinkmüller et al, 2016), testing procedure (Lohrmann et al, 2003;Ritter et al, 2016a) and data analysis (Rosenau et al, 2018a;Rudolf et al, 2021). All samples are first oven dried to remove excess humidity and then stored in the air-conditioned laboratory for several days to equilibrate with ambient laboratory conditions of T = 25°C and ≈ 50 % humidity.…”

Section: Ring-shear Tester Setupmentioning

confidence: 99%

“…For this study we use previously published ring-shear test data by multiple sources (Table 1) which is re-picked and analyzed with the software RST-Evaluation (Rudolf and Warsitzka, 2021).…”

Section: Mohr-coulomb Frictionmentioning

confidence: 99%

Time-dependent Frictional Properties of Granular Materials Used In Analogue Modelling: Implications for mimicking fault healing during reactivation and inversion

Rudolf

Rosenau

Oncken

2022

Preprint

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Abstract. Analogue models are commonly used to model long-term geological processes such as mountain building or basin inversion. The majority of these models use granular materials like sand or glass beads to simulate the brittle behaviour of the crust. In granular materials deformation is localized into shear bands that act as analogues to natural fault zones and detachments. Shear bands aka faults are persistent anomalies in the granular package and are frequently reactivated during an experimental run. This is due to their lower strength in comparison to the undeformed bulk material. When fault motion stops, time dependent healing immediately starts to increase the strength of the fault. Therefore, older faults show a higher strength in comparison to younger faults. This time dependent healing, also called time consolidation, can therefore affect the structural style of an analogue model due to evolution of fault strength over time. Time consolidation is a well known mechanism in granular mechanics but remains poorly characterized for analogue materials and on the timescales of typical analogue models. In this study, we estimate the healing rate of several analogue materials and evaluate the consequences on the reactivation potential of analogue faults. We find that the healing rates are generally below 3 % per tenfold increase in hold time which is comparable to natural fault zones. We qualitatively compare the frictional properties of the materials with grain characteristics and find a weak correlation of healing rates with sphericity and friction with an average quality score. In models where predefined faults exist or reactivation is forced by blocks, the stability region of fault angles that can be reactivated can accordingly decrease by up to 7° over the duration of 12 hours. The stress required to reactivate a preexisting fault can double in the same time which may favor the creation of new faults. In a basin inversion scenario, normal faults can not be inverted due to severe misorientation and therefore time consolidation plays only a minor additional role for such models.

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Ring-shear test data of feldspar sand FS900S used in the Tectonic Modelling Laboratory at the University of Bern (Switzerland)

Zwaan,

Schreurs,

Rudolf

et al. 2022

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RST Evaluation - Scripts for analysing shear experiments from the Schulze RST.pc01 ring shear tester

Cited by 3 publications

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Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

Time-dependent Frictional Properties of Granular Materials Used In Analogue Modelling: Implications for mimicking fault healing during reactivation and inversion

Ring-shear test data of feldspar sand FS900S used in the Tectonic Modelling Laboratory at the University of Bern (Switzerland)

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