Paper Number
MC10 

Session
Rheology of Soil, Mud and Construction Materials

Title
Rheological flow curves for model earth suspension mixtures

Presentation Date and Time
October 10, 2022 (Monday) 2:30

Track / Room
Track 7 / Ontario

Authors (Click on name to view author profile)

1. Pradeep, Shravan (University of Pennsylvania, Earth and Environmental Sciences)
2. Arratia, Paulo E. (University of Pennsylvania, Mechanical Engineering & Applied Mechanics)
3. Meiburg, Eckart (University of California, Santa Barbara, Mechanical Engineering)
4. Jerolmack, Doug J. (University of Pennsylvania)

Author and Affiliation Lines (in printed abstract book)
Shravan Pradeep¹, Paulo E. Arratia², Eckart Meiburg³ and Doug J. Jerolmack^4
1Earth and Environmental Sciences, University of Pennsylvania, Philadelphia, PA 19104; ²Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104; ³Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106; ⁴University of Pennsylvania, Philadelphia, PA 19104

Speaker / Presenter 
Pradeep, Shravan

Keywords
gels; glasses; jammed systems; soil rheology; suspensions

Text of Abstract
Earth surface flows are composed of particulate-fluid mixtures that are diverse in nature. The nature of failure and flow of earth materials depends on the properties of its constituent particulates, namely, size polydispersity, shape, softness, and interparticle interaction potential; landslides arise when material maintains its internal rigidity, while debris flows occur when material is fully fluidized. Our recent results on the rheology of natural debris flow materials indicate that clay/sand content is a critical factor governing differences in flow. We hypothesize that decoupling individual material contributions will help enable the development of bulk rheological relations for particulate-fluid mixtures. To realize this, we study the steady shear rheology of model earth suspension mixtures, composed of kaolinite clay (~60 µm) and silica sand (~65 µm), dispersed in deionized water at a suspension volume fraction of 0.50. Our results show that, for a given volume fraction, the solid volume fraction of clay controls the suspension mechanics. Our results indicate that systematically decreasing the clay content results in lower yield stress values for the idealized earth suspensions. Qualitatively, we observe that the steady shear flow curves cannot be collapsed indicating the coupled nature of cohesion (from clay) and frictional properties (from sand) in these suspensions. We anticipate that our results provide bounds for geophysical suspensions such as debris flows; due to the presence of yield stress, a minimum clay content is necessary to prevent sedimentation and thus sets a lower limit on debris flows makeup while the upper limit is set by the increasing yield stress with the clay content.