Description of new dry granular materials of variable cohesion and friction coefficient: Implications for laboratory modeling of the brittle crust

Abdelmalak, Mohamed Mansour; Bulois, Cédric; Mourgues, R.; Galland, Olivier; Legland, Jean-Baptiste; Gruber, Charles M.

doi:10.1016/j.tecto.2016.03.003

Cited by 38 publications

(68 citation statements)

References 58 publications

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“…While the order of magnitude is correct, this value significantly underestimates uniaxial compressive strengths reported in the literature, in the range of 4–7 MPa [e.g., Schulson and Duval , ; Weiss and Schulson , ]. This may mark out the relevance of the Coulomb's equation as approaching σ n = 0 [see, e.g., Abdelmalak et al ., ] or, in other words, show that extrapolating a Coulomb's failure envelope to such state of stress does not give the intrinsic shear strength of the material, i.e., τ 0 ≠ τ i .…”

Section: Results: Mechanics Of the Competition Between Faulting And Cmentioning

confidence: 99%

Cohesion versus friction in controlling the long‐term strength of a self‐healing experimental fault

et al. 2016

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The Coulomb's failure criterion, which postulates that failure occurs along a fault plane when the applied shear stress overcomes a resistance made of two parts of different nature, cohesion, and friction, remains the standard conceptual framework of faulting mechanics. More recently, rate‐and‐state friction laws became the main modeling tool of the seismic cycle. These laws implicitly assume that only frictional resistance sets the fault strength and its evolution. We therefore raise the question of the role of cohesion and related healing/sealing mechanisms on fault mechanics. We designed an original laboratory experiment based on a model material, an ice thin layer sitting on top of a water tank and mechanically deformed at various rates with a circular Couette‐like geometry. This allowed sliding along the fault plane over arbitrarily large slip distances, and analyzing the competition between faulting and cohesion‐healing rates, whereas frictional resistance, resulting from the fault roughness, is limited in magnitude. We show that cohesion‐healing plays an essential role in the time evolution of the interface strength under constant loading rate. In particular, the magnitudes of shear stress fluctuations are observed to be temperature and velocity weakening. The present experiment shares several properties similar to that of active faults during seismic cycles, suggesting that cohesive healing could control some of these features: scale invariance properties, Gutenberg‐Richter law of rupture event size distribution, Omori's law of energy dissipation, at least after major ruptures, time asymmetry in energy dissipation, and periods of creep under high shear stress alternating with major earthquake‐like ruptures.

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Section: Results: Mechanics Of the Competition Between Faulting And Cmentioning

confidence: 99%

Cohesion versus friction in controlling the long‐term strength of a self‐healing experimental fault

et al. 2016

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“…The first dimensionless parameter to scale the brittle host rock is the ratio of gravitational stress to cohesion Π 1 = ρ r g H / C (Table ). In our experiments, injection is at 3 cm depth, and the model rock cohesion varies from ~100 to ~600 Pa (Abdelmalak et al, ). The values of Π 1 thus range between 0.54 and 4.71.…”

Section: Interpretations and Discussionmentioning

confidence: 98%

Dynamics of Sill and Laccolith Emplacement in the Brittle Crust: Role of Host Rock Strength and Deformation Mode

2017

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Igneous intrusions in sedimentary basins exhibit a great diversity of shapes from thin sheets (e.g., dikes, sills and cone sheets) to massive intrusions (e.g., laccoliths and plugs). Presently, none of the established models of magma emplacement have the capability to simulate this diversity because they account for either purely elastic or purely plastic or purely viscous host rocks, whereas natural rocks are complex visco‐elasto‐plastic materials. In this study, we investigate the effects of elasto‐plastic properties of host rock on magma emplacement using laboratory experiments made of dry granular materials of variable cohesion. Our results show how the deformation mechanism of the host rock controls the emplacement of magma: thin sheet sills form in high‐cohesion materials, which dominantly deform by elastic bending, whereas massive intrusions such as punched laccoliths form in low‐cohesion materials, which dominantly deform by shear failure. Our models also suggest that combined elastic/shear failure deformation modes likely control the emplacement of cone sheets. Our experiments are the first to spontaneously produce diverse, geologically relevant intrusion shapes. Our models show that accounting for the elasto‐plastic behavior of the host rock is essential to filling the gap between the established elastic and plastic models of magma emplacement, and so to reveal the dynamics of magma emplacement in the Earth's brittle crust.

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“…Most granular material like quartz sand or glass beads has similar friction coefficients to rocks (µ ∼ 0.4-0.6) and a properly scaled cohesion in the order of a few tens to hundreds of pascal (e.g. Krantz, 1991;Lohrmann et al, 2003;Panien et al, 2006;Klinkmüller et al, 2016;Ritter et al, 2016;Abdelmalak et al, 2016).…”

Section: Frictional-plastic Rock Analogue Materialsmentioning

confidence: 99%

Analogue earthquakes and seismic cycles: experimental modelling across timescales

2017

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Abstract. Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short-and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.

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Description of new dry granular materials of variable cohesion and friction coefficient: Implications for laboratory modeling of the brittle crust

Cited by 38 publications

References 58 publications

Cohesion versus friction in controlling the long‐term strength of a self‐healing experimental fault

Cohesion versus friction in controlling the long‐term strength of a self‐healing experimental fault

Dynamics of Sill and Laccolith Emplacement in the Brittle Crust: Role of Host Rock Strength and Deformation Mode

Analogue earthquakes and seismic cycles: experimental modelling across timescales

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