Tunnel excavation in granular media: the role of force chains

2021 ◽  
Vol 23 (4) ◽  
Author(s):  
Raj Kumar Pal ◽  
Robert Buraque de Macedo ◽  
José E Andrade
Keyword(s):  
Granular Media ◽  
Force Chains ◽  
Tunnel Excavation

Link between single-particle properties and macroscopic properties in particulate assemblies: role of structures within structures

2007 ◽  
Vol 365 (1861) ◽  
pp. 2879-2891 ◽  
Author(s):  
S.J Antony
Keyword(s):  
Single Particle ◽  
Granular Media ◽  
Force Chains ◽  
Force Transmission ◽  
Interparticle Interactions ◽  
Particulate Materials ◽  
Particulate Media ◽  
Particle Properties ◽  
Particulate Systems

The prevalence of particulate materials in modern industrial processes and products provides a significant motivation to achieve fundamental understanding of the bulk behaviour of particulate media. The rapid progress being made with atomic force microscopy and related particle characterization techniques pushes the limits of micro- and nanotechnologies such that interparticle interactions can be engineered to fabricate particulate assemblies to deliver specific functionalities. In this paper, primarily based on discrete element method simulations that we performed over the past 10 years, we summarize the key findings on the role of force transmission networks in dense particulate systems subjected to shearing. In general, the macroscopic strength characteristics in particulate systems is dictated by the distribution of heavily loaded contacts, also referred to as ‘strong’ force chains. Surprisingly, they constitute only a limited proportion of all contacts in particulate systems. They act like a ‘granular brain’ (memory networks) at particle scale. We show that the structural arrangement of the force chains and their evolution during loading depends on the single-particle properties and the initial packing condition in particulate assemblies. Further, the ‘nature’ of force chains in sheared granular media induces larger ‘solid’ grains to behave like ‘fluid’ particles, retarding their breakage. Later, we probe for ways by which we can control the signature of memory networks in packed beds, for example by applying an external electrical field in a densely packed particulate bed subjected to shearing (combined electromechanical loading). Though further research is required to account for more realistic conditions and preferably to allow particles to self-organize to strength specifications, understanding the hidden memory networks in particulate materials could be exploited to optimize their collective strength.

Role of contact couples and couple stress in the behaviour of granular media

1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-87-Pr8-94
Author(s):  
F. Dedecker ◽  
Ph. Dubujet ◽  
B. Cambou
Keyword(s):  
Couple Stress ◽  
Granular Media

The impact of fluid flow on force chains in granular media

2017 ◽  
Vol 110 (4) ◽  
pp. 041907 ◽  
Author(s):  
Nariman Mahabadi ◽  
Jaewon Jang
Keyword(s):  
Fluid Flow ◽  
Granular Media ◽  
Force Chains ◽  
The Impact

scholarly journals Continuum Modeling of Granular Media

2014 ◽  
Vol 66 (5) ◽  
Author(s):  
J. D. Goddard
Keyword(s):  
Granular Flow ◽  
Granular Media ◽  
Evolution Equations ◽  
Particle Migration ◽  
Internal Variables ◽  
Continuum Modeling ◽  
Material Instability ◽  
Rapid Flow ◽  
Internal Balance

This is a survey of the interesting phenomenology and the prominent regimes of granular flow, followed by a unified mathematical synthesis of continuum modeling. The unification is achieved by means of “parametric” viscoelasticity and hypoplasticity based on elastic and inelastic potentials. Fully nonlinear, anisotropic viscoelastoplastic models are achieved by expressing potentials as functions of the joint isotropic invariants of kinematic and structural tensors. These take on the role of evolutionary parameters or “internal variables,” whose evolution equations are derived from the internal balance of generalized forces. The resulting continuum models encompass most of the mechanical constitutive equations currently employed for granular media. Moreover, these models are readily modified to include Cosserat and other multipolar effects. Several outstanding questions are identified as to the contribution of parameter evolution to dissipation; the distinction between quasielastic and inelastic models of material instability; and the role of multipolar effects in material instability, dense rapid flow, and particle migration phenomena.

Role of contact heterogeneities on macroscopic elastic properties of granular media

2010 ◽  
Author(s):  
Ratnanabha Sain ◽  
Gary Mavko ◽  
Tapan Mukerji
Keyword(s):  
Elastic Properties ◽  
Granular Media

Fracture pattern formation in frictional, cohesive, granular material

2010 ◽  
Vol 368 (1910) ◽  
pp. 95-118 ◽  
Author(s):  
Alison Ord ◽  
Bruce E. Hobbs
Keyword(s):  
Pattern Formation ◽  
Granular Media ◽  
Large Scale ◽  
High Stress ◽  
Reaction Diffusion ◽  
Fracture Pattern ◽  
Reaction Diffusion Equations ◽  
Three Dimensions ◽  
Localized Deformation

Naturally, deformed rocks commonly contain crack arrays (joints) forming patterns with systematic relationships to the large-scale deformation. Kinematically, joints can be mode-1, -2 or -3 or combinations of these, but there is no overarching theory for the development of the patterns. We develop a model motivated by dislocation pattern formation in metals. The problem is formulated in one dimension in terms of coupled reaction–diffusion equations, based on computer simulations of crack development in deformed granular media with cohesion. The cracks are treated as interacting defects, and the densities of defects diffuse through the rock mass. Of particular importance is the formation of cracks at high stresses associated with force-chain buckling and variants of this configuration; these cracks play the role of ‘inhibitors’ in reaction–diffusion relationships. Cracks forming at lower stresses act as relatively mobile defects. Patterns of localized deformation result from (i) competition between the growth of the density of ‘mobile’ defects and the inhibition of these defects by crack configurations forming at high stress and (ii) the diffusion of damage arising from these two populations each characterized by a different diffusion coefficient. The extension of this work to two and three dimensions is discussed.

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