Multilayer models for shallow two-phase debris flows with dilatancy effects

Garres-Díaz, José; Bouchut, François; Fernández-Nieto, Enrique D.; Mangeney, A.; Narbona-Reina, Gladys

doi:10.1016/j.jcp.2020.109699

Cited by 8 publications

(10 citation statements)

References 23 publications

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“…The experimental data show that the passage of the flow front at a given point is followed by a short under-pressure phase and a later and longer over-pressure phase. Roche et al (2010) propose that the under-pressure stage is mainly caused by the basal slip boundary condition and possibly by dilatancy processes (Garres-Díaz et al 2020;Bouchut et al 2021), which is supported by simulations (Breard et al 2019a). Moreover, the minimum value reached during the under-pressure phase was empirically correlated to the slip velocity (𝑢 slip ; Roche 2012).…”

Section: Simulations On Horizontal Planesmentioning

confidence: 59%

The influence of gas pore pressure in dense granular flows: numerical simulations versus experiments and implications for pyroclastic density currents

et al. 2021

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We investigate the influence of gas pore pressure in granular flows through numerical simulations on horizontal and low-angle inclined surfaces. We present a two-phase formulation that allows description of dam-break experiments considering high-aspect-ratio collapsing columns and depth-dependent variations of flow properties. The model is confirmed by comparing its results with data of analogue experiments. The results suggest that a constant, effective pore pressure diffusion coefficient can be determined in order to reproduce reasonably well the dynamics of the studied dam-break experiments, with values of the diffusion coefficient consistent with experimental estimates from defluidizing static columns. The discrepancies between simulations performed using different effective pore pressure diffusion coefficients are mainly observed during the early acceleration stage, while the final deceleration rate, once pore pressure has been dissipated, is similar in all the studied numerical experiments.However, these short-lasting discrepancies in the acceleration stage can be manifested in large differences in the resulting run-out distance. We also analyze the pore pressure at different distances along the channel. Although our model is not able to simulate the under-pressure phase generated by the sliding head of the flows in experiments and measured beneath the flowsubstrate interface, the spatio-temporal characteristics of the subsequent over-pressure phase are compatible with experimental data. Additionally, we studied the deposition dynamics of the granular material, showing that the timescale of deposition is much smaller than that of the granular flow, while the time of the deposition onset varies as a function of the distance from the reservoir, being strongly controlled by the surface slope angle. The simulations reveal that an increment of the surface slope angle from 0° to 10° is able to increase significantly the flow run-out distance (by a factor between 2.05 and 2.25, depending on the fluidization conditions). This has major implications for pyroclastic density currents, which typically propagate at such gentle slope angles.

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Section: Simulations On Horizontal Planesmentioning

confidence: 59%

The influence of gas pore pressure in dense granular flows: numerical simulations versus experiments and implications for pyroclastic density currents

et al. 2021

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“…Yavari-Ramshe and Ataie-Ashtiani [2016] and Delannay et al [2017] give a more comprehensive review of thin-layer models. Current research focuses include modeling of multi-layer flows [Fernández-Nieto et al, 2018;Garres-Díaz et al, 2020], bed erosion along the flow path [Hungr, 1995;Bouchut et al, 2008;Iverson, 2012;Pirulli and Pastor, 2012] and the description of two-phase flows [e.g. Pudasaini, 2012;Rosatti and Begnudelli, 2013;Iverson and George, 2014;Bouchut et al, 2015Bouchut et al, , 2016Pastor et al, 2018a].…”

Section: Introductionmentioning

confidence: 99%

“…(2017) give a more comprehensive review of thin‐layer models. Current research focuses include modeling of multi‐layer flows (Fernández‐Nieto et al., 2018; Garres‐Díaz et al., 2020), bed erosion along the flow path (Bouchut et al., 2008; Hungr, 1995; Iverson, 2012; Pirulli & Pastor, 2012) and the description of two‐phase flows (e.g., Bouchut et al., 2015, 2016; Iverson & George, 2014; Pastor et al., 2018b; Pudasaini, 2012; Rosatti & Begnudelli, 2013).…”

Section: Introductionmentioning

confidence: 99%

Topography Curvature Effects in Thin‐Layer Models for Gravity‐Driven Flows Without Bed Erosion

et al. 2021

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The propagation of rapid gravity-driven flows (Iverson & Denlinger, 2001) occurring in mountainous or volcanic areas is a complex and hazardous phenomenon. A wide variety of events are associated with these flows, such as rock avalanches, debris avalanches and debris, mud or hyper-concentrated flows (Hungr et al., 2014). The understanding and estimation of their propagation processes is important for sediment fluxes quantification, for the study of landscapes dynamics. Besides, gravity-driven flows can have a significant economic impact and endanger local populations (Hungr et al., 2005;Petley, 2012;Froude & Petley, 2018). In order to mitigate these risks, it is of prior importance to estimate the runout, dynamic impact and travel time of potential gravitational flows.This can be done empirically, but physically based modeling is needed to investigate more precisely the dynamics of the flow, in particular due to the first-order role of local topography. Over the past decades, thin-layer models (also called shallow-water models) have been increasingly used by practitioners. Their main assumption is that the flow extent is much larger than its thickness, so that the kinematic unknowns are reduced to two variables: the flow thickness and its depth-averaged velocity. The dimension of the problem is thus lower, allowing for relatively fast numerical computations. The first and simplest form of thin-layer equations was given by Barré de Saint-Venant (1871) for almost flat topographies. The 1D formulation (i.e., for topographies given by a 1D graph Z = Z(X)) for any bed inclination and small curvatures was derived by Savage and Hutter (1991). This model has since been extended to real 2D topographies (i.e., given by a 2D graph Z = Z (X, Y)). Some of the software products based on thin-layer equations are currently used for hazard assessment to derive, for instance, maps of maximum flow height and velocity. Examples include RAMMS (

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“…The above numerical simulation originated from depthaverage/integral model coupling entrainment rate formula could restore the evolution characteristics of some typical debris flow events to some extent, especially the characteristic of rheology and the amplification effect. However, there are yet some problems to be solved in theory (Iverson and Ouyang, 2015;Garres-Díaz et al, 2020).…”

Section: Debris Flow Starting From Gully or Channel (Gully Debris Flow)mentioning

confidence: 99%

Research Progress of Initial Mechanism on Debris Flow and Related Discrimination Methods: A Review

Fan

et al. 2021

Front. Earth Sci.

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The initial of debris flow can be classified into two types based on their triggering positions, that is, debris flow from slope and debris flow from gully or channel. For the former, great progress has been achieved on the mechanisms of soil failure and liquefaction. The framework established by a series of theories or laws, such as the Mohr–Coulomb criteria, the unsaturated soil mechanics, and the critical state of soil mass, has been used widely in industry and research. However, the details and discrimination basis for the transformation process from landslide into debris flow still need to be further clarified. Relatively, debris flow from gully or channel is more complex due to its various mass sources and the diversity of processes. Nevertheless, through a great number of case studies and experimental statistics, people have gradually recognized the influential rule and critical condition of factors from landform, hydrology, and other aspects on debris flow initiation. Furthermore, based on the theories of granular flow, continuum mechanics, and rheological law, some typical event-based scenarios can also be reproduced by different single-/two-phase depth integral/average numerical models. However, some key knowledge on mechanism and application level is still insufficient, such as the erosion and entrainment mechanism of materials from different sources, the boundary tractions and materials exchange, as well as the selection of prediction indicators. Three current discriminated methodologies for debris flow initiation, that is, the safety factor method, the rainfall indicator method, and the comprehensive assessment method, were summarized in this article. Considering the technical limitation of each methodology, it is believed that the establishment or improvement of a unified, stable, and open-access database system for event registration and query, as well as the development of large-scale and high-precision rainfall monitoring, is still regarded as the important aspect of debris flow prevention in the future. In addition, as an economic and efficiency means for obtaining information on potential threats and real-time hazard messages, the multielement method for debris flow is recommended as a long-term reference.

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Multilayer models for shallow two-phase debris flows with dilatancy effects

Cited by 8 publications

References 23 publications

The influence of gas pore pressure in dense granular flows: numerical simulations versus experiments and implications for pyroclastic density currents

The influence of gas pore pressure in dense granular flows: numerical simulations versus experiments and implications for pyroclastic density currents

Topography Curvature Effects in Thin‐Layer Models for Gravity‐Driven Flows Without Bed Erosion

Research Progress of Initial Mechanism on Debris Flow and Related Discrimination Methods: A Review

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