The material point method for simulating dense snow avalanches over complex real terrain

2021 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Material Point Method ◽  
Granular Flows ◽  
Material Point ◽  
Full Scale ◽  
Point Method ◽  
Constitutive Law ◽  
Snow Avalanches ◽  
Failure Patterns ◽  
Snow Properties ◽  
Modified Cam Clay

<p>Various dynamics models can reproduce the motion of avalanches from release to deposition. These models often simulate a conceptual avalanche, adopt depth-averaged approaches and do not resolve variations along flow depth direction, and thus have clear limitations. This study presents three-dimensional, full-scale modeling of dense snow avalanches performed using the complex real terrain of the Vallée de la Sionne avalanche test site in Switzerland. We use the material point method (MPM) and a large-strain elastoplastic constitutive law for snow based on a Modified Cam Clay model. In our simulations, various and transient avalanche flow regimes are simulated by setting distinct snow properties. Snow avalanches are investigated from release to deposition. Detailed simulation results include the initial failure patterns, the mechanical behavior during the flow, and the characteristics of the final avalanche deposits. More specifically in the release zone, we can observe brittle and ductile fractures depending on the defined snow properties. During the flow phase, we monitor the temporal and spatial variations of snow density in the avalanche. In particular, cohesionless granular flows, cohesive granular flows, and plug flows are associated with snow fracture, compaction, and expansion. Finally, we can observe the structure of the avalanche deposit surfaces which show distinguishable differences in terms of smoothness, granulation, and compacting shear planes. This new model can offer a quantitative analysis for studying avalanches in different regimes and provide a powerful tool for exploring the dynamics of full-scale avalanches on complex real terrain, with high physical detail.</p>

Investigating erosion and entrainment of snow avalanches using the material point method

2021 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Camille Ligneau ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Snow Cover ◽  
Large Scale ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Snow Avalanches ◽  
Runout Distance ◽  
Gravity Driven ◽  
Erosion Mechanisms ◽  
Dynamics Models

<p>Erosion and entrainment are critical processes in gravity-driven mass flows like snow avalanches, as they can significantly change the flow mass and momentum and thus affect the flow dynamics. In snow avalanches, snow cover can be considerably eroded but only partially entrained into the flow. Differentiating erosion and entrainment gives more accurate prediction of the increased flow mass and offers information on eroded snow cover remaining on the slope, but is challenging in practice. This study investigates snow avalanche erosion and entrainment with the material point method, focusing on exploring various erosion mechanisms, differences in erosion and entrainment, and their possible influences on runout distance. By using different mechanical properties for the flowing snow, distinct erosion patterns are observed and the corresponding temporal evolutions of entrainment, erosion, and deposition in the erodible bed are examined. Erosion and entrainment require an appropriate combination of snow friction and cohesion of the bed. If cohesion and/or friction are too low, the bed will naturally be unstable. On the other hand, highly cohesive and frictional bed will prevent erosion. For intermediate values, erosion and entrainment can be notable, and the amount of eroded snow shows a clear negative correlation with snow friction and cohesion while the entrained snow does not demonstrate a strong tendency. Furthermore, the release and erodible bed lengths are varied to study their effect on erosion and entrainment propensity. It is found that the increase in the lengths of the release zone and erodible bed leads to more erosion and entrainment as expected, but not necessarily to a longer runout distance. In our simulations, the release and erodible bed lengths are positively and negatively correlated with the runout distance, respectively. This implies that the runout distance can have opposite trends with erosion and entrainment, which might be closely related to the energy change of the simulated avalanches from the outlet of the erodible bed to the final deposit. Our results shed more light into the erosion and entrainment mechanisms and may contribute to improve related parametrizations in large-scale avalanche dynamics models.</p>

scholarly journals An Implicit Material Point Method Applied to Granular Flows

2017 ◽  
Vol 175 ◽  
pp. 226-232 ◽  
Author(s):  
Ilaria Iaconeta ◽  
Antonia Larese ◽  
Riccardo Rossi ◽  
Eugenio Oñate
Keyword(s):  
Material Point Method ◽  
Granular Flows ◽  
Material Point ◽  
Point Method

Modelling Multi-Cracking in Thin Films during Constrained Sintering Using Anisotropic Constitutive Law and Material Point Method

2010 ◽  
Vol 62 ◽  
pp. 191-196 ◽  
Author(s):  
Fan Li ◽  
Jing Zhe Pan
Keyword(s):  
Thin Films ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Constitutive Law ◽  
Surface Coatings ◽  
Sintering Process ◽  
Straightforward Manner ◽  
Random Nature ◽  
Constrained Sintering

The sintering of thin films is widely used for surface coatings and because of its technological importance has generated extensive research interest. During the sintering process, the thin film is constrained by the substrate, which generates considerably high levels of stresses. Crackings are often observed and are considered as one of the major problems of the surface coating technique. This paper has proposed a new numerical method in order to tackle the traditional difficulties in simulating multi-crackings during constrained sintering. Main features of the present method include: (i) the material data is represented by an anisotropic constitutive law, (ii) a new numerical scheme is developed for the crack initialization and growth based on the material point method, (iii) the 3D viscous film shrinkage model is solved by using a dynamic FE scheme, and (iv) the random nature of the initial green body density is represented by statistical variabilities. It is shown that the model proposed by the present paper is capable for the nucleation and propagation of multi-cracks in a straightforward manner. Cracking patterns are shown to be consistent with experimental understandings. The focus of the paper is on the numerical issues and demonstrating the capacity of the model.

Numerical simulation of installation of jacked piles in sand using material point method

2018 ◽  
Vol 55 (1) ◽  
pp. 131-146 ◽  
Author(s):  
R. Lorenzo ◽  
R.P. da Cunha ◽  
M.P. Cordão Neto ◽  
J.A. Nairn
Keyword(s):  
Constitutive Models ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Deep Foundations ◽  
Lateral Capacity ◽  
Pile Installation ◽  
Modified Cam Clay ◽  
Semi Empirical ◽  
Cam Clay

Pile installation has a great impact on the subsequent mechanical pile response. It is not, however, routinely incorporated in the numerical analyses of deep foundations in sand. Some of the difficulties associated with the simulation of the installation process are related to the fact that large deformations and distortions will eventually appear. The finite element method is not well suited to solve problems of this nature. Hence, an alternative procedure is tested herein, by using the material point method to simulate the installation of statically jacked or pushed-in type piles, which has successfully demonstrated its capacity to deal with this simulation. Two constitutive models were also tested, i.e., the modified Cam clay (MCC) and the subloading Cam clay (SubCam), allowing a clear perception of the great advantage to consider the soil with the SubCam model. The simulations have indeed reproduced some of the important features of the pile installation process, such as the radial stress acting around the pile’s shaft or the shaft’s lateral capacity, among other issues. The numerical results were additionally compared with known (semi-empirical) methods to derive the lateral capacity of the shaft, with a good and practical outcome.

scholarly journals Towards an understanding of the chemo-mechanical influences on kidney stone failure via the material point method

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0240133
Author(s):  
Samuel J. Raymond ◽  
Janille Maragh ◽  
Admir Masic ◽  
John R. Williams
Keyword(s):  
Kidney Stones ◽  
Complex Structure ◽  
Material Point Method ◽  
Renal Calculi ◽  
Material Point ◽  
Point Method ◽  
Tensile Fracture ◽  
Failure Behavior ◽  
Failure Patterns ◽  
Extracorporeal Shock Wave

This paper explores the use of the meshfree computational mechanics method, the Material Point Method (MPM), to model the composition and damage of typical renal calculi, or kidney stones. Kidney stones are difficult entities to model due to their complex structure and failure behavior. Better understanding of how these stones behave when they are broken apart is a vital piece of knowledge to medical professionals whose aim is to remove these stone by breaking them within a patient’s body. While the properties of individual stones are varied, the common elements and proportions are used to generate synthetic stones that are then placed in a digital experiment to observe their failure patterns. First a more traditional engineering model of a Brazil test is used to create a tensile fracture within the center of these stones to observe the effect of stone consistency on failure behavior. Next a novel application of MPM is applied which relies on an ultrasonic wave being carried by surrounding fluid to model the ultrasonic treatment of stones commonly used by medical practitioners. This numerical modeling of Extracorporeal Shock Wave Lithotripsy (ESWL) reveals how these different stones failure in a more real-world situation and could be used to guide further research in this field for safer and more effective treatments.

A Material Point Method for Alpine Mass Movements

2021 ◽  
Author(s):  
Alessandro Cicoira ◽  
Lars Blatny ◽  
Xingyue Li ◽  
Fabrizio Troilo ◽  
Robert Kenner ◽  
...  
Keyword(s):  
Climate Change ◽  
Initial Conditions ◽  
Quantitative Description ◽  
Material Point Method ◽  
Material Point ◽  
Phase Changes ◽  
Point Method ◽  
Constitutive Law ◽  
Gravitational Mass ◽  
Mass Movements

<p>Gravitational mass movements pose a threat to the population of numerous mountainous regions around the globe. Climate change affects these processes and their related hazards by influencing their triggering, flow and deposition mechanisms, overall increasing the number of natural catastrophes. Numerical modelling is an essential tool for the analysis and the management of such hazards: it allows the quantitative description of the runout and pressure of rapid mass movements and may contribute to better understand the effects of climate change on their size, frequency, and dynamics. Several depth-averaged models are already operational and commonly applied by practitioners and scientists. Yet, a unified model able to simulate multi-phase cascading events, including their initiation, propagation, entrainment and finally impact on structures is still missing. Hence, more detailed models are  required to advance our understanding of the physics behind gravitational mass movements and ultimately to contribute improving hazard assessment and risk management.</p><p>Here, we present some preliminary results of the development of a hybrid Eulerian-Lagrangian Material Point Method (MPM) with finite strain elasto-plasticity to simulate in a unified manner: i) permafrost instabilities and failure initiation; ii) rock and ice avalanche dynamics; iii) solid-fluid interaction and phase transition from rock avalanches to debris-flows. In order to simulate the mechanical behaviour of rock and ice, we propose a Drucker-Prager softening constitutive law accounting for cohesion, internal and residual friction. We calibrate this constitutive law on the basis of state of the art laboratory experiments. The model is applied to synthetic slope geometries to evaluate their stability and investigate subsequent rock fragmentation processes. At a larger scale, dynamics simulations are compared against observations of full-scale process chains. In particular, we implement the two real-scale cases of the rock-avalanche from the Piz Cengalo (CH) and ice- and snow-avalanche from the Grandes Jorasses (IT). The 3D implementation of the model allows to accurately reproduce the initial conditions of an event and complex phenomena such as reported ballistic trajectories non adherent to the ground. Secondary releases due to the mass flow (such as snow or glacier-ice entertainment) and phase changes can be simulated realistically. We test the potential of the model in a broad range of settings and highlight the major gaps to be filled in the near future.</p>

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