Multi-scale and multi-physics modelling for complex materials

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Numerical modelling of thermo-hydromechanical (THM) in deforming porous media for subsurface systems

The study of multiphase flow and heat flow in partially saturated porous media is important in environmental geomechanics engineering because of its relevance to consolidation of porous media in unsaturated zone. A numerical model which describes the thermo-hydro-mechanical (THM) coupled problems in deformable porous material with two-phase flow has been developed. The relationships between capillary pressure, saturation of water and relative permeabilities of water and gas, proposed by Brooks and Corey was used. An extended study of the numerical model, based on the COMES-GEO code was conducted recently to solve unsaturated problems in local condition of Kg. Puteh wellfield, Kota Bharu. This site is a potential shallow aquifer which contribute to the largest groundwater supply in Kota Bharu, Kelantan. Some numerical investigation on the proposed formulation is discussed with illustrative example problems to demonstrate solution procedures and validating of the model

On stepwise advancement of fractures and pressure oscillations in saturated porous media

Comments to K.M. Pervaiz Fathima, Ren\'e de Borst, Implications of single or multiple pressure degrees of freedom at fracture in fluid saturated porous media, Engineering Fracture Mechanics, 213 (2019), 1-20

Coupled and multiphysics phenomena

The contributions assembled in the present volume proceed from the lectures of the 2015 ALERT Geomaterials Doctoral School devoted to Coupled and Multiphysics Phenomena. The school has been organized and coordinated by Bernhard Schrefler (Universit\ue0 degli Studi di Padova), Lorenzo Sanavia (Universit\ue0 degli Studi di Padova) and Fr\ue9d\ue9ric Collin (Universit\ue9 de Liege). When dealing with the behaviour of multiphase porous systems, e.g. geomaterials, instances of complexity and interaction are numerous, mainly because of the coexistence of several constituents and phases, their physical and mechanical interactions, their reactivity and their often non-linear behaviour. The study of these coupled processes deals with a large number of applications, e.g. in geomechanics: underground structures (storage, tunnelling), surface structures (earth and concrete dams, embankments) as well as the exploitation of geo-resources (petroleum and gas extraction, mines and quarries). This volume contains nine chapters in which emphasis is given to the presentation of the fundamental and new concepts that help understanding coupled and multiphysics phenomena in porous systems. The contributions cover experimental, theoretical, as well as numerical aspects. The school is divided into three main parts: the description of the couplings in multiphysics phenomena, including the experimental developments; the mathematical modelling of all these coupled processes, with an introduction to the constitutive modelling taking into account the dilatancy, which characterizes the mechanical behaviour of geomaterials; the numerical implementation of the mathematical models, comprising constitutive equations as well as balance equations and finally numerical modelling through advanced applications

Numerical simulation of forerunning fracture in saturated porous solids with hybrid FEM/Peridynamic model

In this paper, a novel hybrid FEM and Peridynamic modeling approach proposed in Ni et al. (2020) is used to predict the dynamic solution of hydro-mechanical coupled problems. A modified staggered solution algorithm is adopted to solve the coupled system. A one-dimensional dynamic consolidation problem is solved first to validate the hybrid modeling approach, and both -convergence and -convergence studies are carried out to determine appropriate discretization parameters for the hybrid model. Thereafter, dynamic fracturing in a rectangular dry/fully saturated structure with a central initial crack is simulated both under mechanical loading and fluid-driven conditions. In the mechanical loading fracture case, fixed surface pressure is applied on the upper and lower surfaces of the initial crack near the central position to force its opening. In the fluid-driven fracture case, the fluid injection is operated at the centre of the initial crack with a fixed rate. Under the action of the applied external force and fluid injection, forerunning fracture behavior is observed both in the dry and saturated conditions.Comment: arXiv admin note: text overlap with arXiv:2307.1092

Finite element modelling of shear bands in porous media by means of non-local viscoplasticity

This work presents a consistent numerical approach in the framework of analyzing the localization process in a slope stability problem. An already existing model, embedded in Mechanics of multiphase porous media, is enhanced with local and non-local elasto-viscoplastic constitutive models to obtain regularized numerical solutions. The initiation and the propagation of the shear band are effectively described by means of FEM analysis, regardless of the mesh size adopted. The strain localization process realistically occurs within the shear band failure mode and its size is governed by the internal length variable, which can be directly estimated by experimental approaches

Hybrid FEM and peridynamic simulation of hydraulic fracture propagation in saturated porous media

This paper presents a hybrid modeling approach for simulating hydraulic fracture propagation in saturated porous media: ordinary state-based peridynamics is used to describe the behavior of the solid phase, including the deformation and crack propagation, while FEM is used to describe the fluid flow and to evaluate the pore pressure. Classical Biot poroelasticity theory is adopted. The proposed approach is first verified by comparing its results with the exact solutions of two examples. Subsequently, a series of pressure- and fluid-driven crack propagation examples are solved and presented. The phenomenon of fluid pressure oscillation is observed in the fluid-driven crack propagation examples, which is consistent with previous experimental and numerical evidences. All the presented examples demonstrate the capability of the proposed approach in solving problems of hydraulic fracture propagation in saturated porous media

Averaging theory for description of environmental problems: What have we learned?

Advances in Water Resources has been a prime archival source for implementation of averaging theories in changing the scale at which processes of importance in environmental modeling are described. Thus in celebration of the 35th year of this journal, it seems appropriate to assess what has been learned about these theories and about their utility in describing systems of interest. We review advances in understanding and use of averaging theories to describe porous medium flow and transport at the macroscale, an averaged scale that models spatial variability, and at the megascale, an integral scale that only considers time variation of system properties. We detail physical insights gained from the development and application of averaging theory for flow through porous medium systems and for the behavior of solids at the macroscale. We show the relationship between standard models that are typically applied and more rigorous models that are derived using modern averaging theory. We discuss how the results derived from averaging theory that are available can be built upon and applied broadly within the community. We highlight opportunities and needs that exist for collaborations among theorists, numerical analysts, and experimentalists to advance the new classes of models that have been derived. Lastly, we comment on averaging developments for rivers, estuaries, and watersheds