Paper Number
DP2 My Program
Session
Dense Particulate Systems
Title
Ductile-to-brittle transition in soft earth particulate systems
Presentation Date and Time
October 14, 2024 (Monday) 1:50
Track / Room
Track 3 / Waterloo 5
Authors
- Pradeep, Shravan (University of Pennsylvania, Earth and Environmental Science)
- Arratia, Paulo E. (University of Pennsylvania, Mechanical Engineering and Applied Mechanics)
- Jerolmack, Douglas J. (University of Pennsylvania, Department of Earth and Environmental Science)
Author and Affiliation Lines
Shravan Pradeep1, Paulo E. Arratia2 and Douglas J. Jerolmack1
1Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104; 2Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104
Speaker / Presenter
Pradeep, Shravan
Keywords
colloids; dense systems; gels; networks; particles; particualte systems; real-world rheology; suspensions; sustainability
Text of Abstract
Catastrophic fluidization and failure of wet soil, by intense rainfall, or is shaken by an earthquake, results in debris flows and landslides. Rheologically, prior research has been focused on two extreme states of saturated soil: sand-rich and clay-rich. The sand-rich slurries are treated as granular suspensions, where failure is related to an unjamming transition and the friction is controlled by particle concentration and pore pressure. On the other hand, clay-rich mud flows are modeled as complex fluids akin to gels, where yielding and shear-thinning behaviors arise from inter-particle attraction and clustering. Here, we investigate the mechanical failure of model soil material: a multiphase suspension mixture of non-swelling kaolin clay and silica sand particles. Steady shear and transient rheological characterization of these system reveal a continuous transition from ductile yielding in clay-rich mixtures to brittle (Mohr-Coulomb-like) ductile yielding in sand rich mixtures. The transition is accompanied by three rheological signatures: (1) an increase in the stress overshoot associated with transient yielding; (2) an increase in rate-dependent plastic dissipation, associated with the emergence of a robust shear-thinning exponent of 1/2; and (3) an increase in the axial thrust. We propose a general rheological constitutive relation for soil suspensions, with the microscopic rearrangement time that is controlled by the interaction between cohesive and frictional elements in the soft particulate system. The framework presented here is supported by elastoplastic models that capture yielding dynamics in amorphous materials.