Micromechanical Analysis of Stresses and Instabilities in Wet Granular Materials: Homogenization and Discrete Element Approaches

Farahnak Langroudi, Mojtaba

Micromechanical Analysis of Stresses and Instabilities in Wet Granular Materials: Homogenization and Discrete Element Approaches

dc.contributor.advisor	Wan, Richard
dc.contributor.advisor	Nicot, Francois
dc.contributor.author	Farahnak Langroudi, Mojtaba
dc.contributor.committeemember	Buscarnera, Giuseppe
dc.contributor.committeemember	Federico, Salvatore
dc.contributor.committeemember	Priest, Jeffrey
dc.contributor.committeemember	Jasso, Martin
dc.date.accessioned	2023-10-31T19:32:39Z
dc.date.available	2023-10-31T19:32:39Z
dc.date.issued	2023-10-30
dc.description.abstract	This thesis presents the micromechanical analysis of wet granular material behavior within the pendular regime where particles are held by distinct liquid bridges through the action of capillarity and thin film adhesion. The presence of air and liquid phases within the pore space of solid particles significantly impacts the mechanical properties of wet geomaterials, and hence their failure behavior as a material instability phenomenon. The first question is how does the stress transport to the different phases (air, water, and solid) as a function of the internal microstructural construct and interfaces? An analytical expression of the internal stress partitioning between air, water and solid is formally derived via a homogenization scheme which upscales the interfacial surface tension physics at the pore scale to the macroscopic (specimen) scale. Focusing particularly on fine particles in the micrometer range, the study encompasses the two dominant mechanisms in wet conditions: adsorption and capillarity. These mechanisms consider the role of adsorbed liquid films governed by a disjoining pressure and liquid bridges arising from matric suction as a water potential. The final derivation reveals the tensorial nature of an adsorptive-capillary stress variable that is closely linked to the topology of the fluid partitions in the pore network, and is hence non-spherical. The next question is, among the various stress components, how does the contact (solid skeleton) stress tensor relate to the strain tensor to describe the constitutive behavior of wet granular materials? A multi-directional probing numerical experiment on a Representative Element Volume (REV) is implemented in Discrete Element Method (DEM) simulations to link increments of stresses to increments of strains through a bridging of grain/pore scale and the REV scale. Essentially, the incremental constitutive tangent operator is reconstructed through a perturbation analysis. This methodology also offers the possibility of micromechanically investigating bifurcation phenomena somewhat unexplored for partially saturated conditions. As a result, aspects of material instability, failure mechanisms, and shear band localization are examined by probing into the spectral characteristics of the micromechanically and hydromechanically informed tangent operator and the second-order work instability criterion for both dry and wet states.
dc.identifier.citation	Farahnak Langroudi, M. (2023). Micromechanical analysis of stresses and instabilities in wet granular materials: homogenization and discrete element approaches (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/117490
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Wet Granular Materials
dc.subject	Micromechanics
dc.subject	Partially Saturated
dc.subject	Stress Transmission
dc.subject	Instability
dc.subject	Localization
dc.subject.classification	Engineering--Civil
dc.subject.classification	Geotechnology
dc.subject.classification	Geology
dc.subject.classification	Soil Science
dc.subject.classification	Engineering--Mechanical
dc.title	Micromechanical Analysis of Stresses and Instabilities in Wet Granular Materials: Homogenization and Discrete Element Approaches
dc.type	doctoral thesis
thesis.degree.discipline	Engineering – Civil
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.