Fracturing in Wet Granular Media Illuminated by Photoporomechanics

Journal Article · Tue Dec 27 00:00:00 EST 2022 · Physical Review Applied

DOI:https://doi.org/10.1103/physrevapplied.18.064081· OSTI ID:2420773

Meng, Yue ^[1]; Li, Wei ^[2]; Juanes, Ruben ^[2]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); OSTI
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Here, we study fluid-induced deformation and fracture of granular media and apply photoporomechanics to uncover the underpinning grain-scale mechanics. We fabricate spherical photoelastic particles of 2-mm diameter to form a monolayer granular pack in a circular Hele-Shaw cell that is initially filled with a viscous fluid. The key distinct feature of our system is that, with spherical particles, the granular pack has a connected pore space, thus allowing for pore-pressure diffusion and the study of effective stress in coupled poromechanical processes. We inject air into the fluid-filled photoelastic granular pack, varying the initial packing density and confining weight. With our recently developed experimental technique, photoporomechanics, we find two different modes of fluid invasion: fracturing in fluid-filled elastic media (with strong photoelastic response) and viscous fingering in frictional fluids (with weak or negligible photoelastic response). We directly visualize the evolving effective stress field and discover an effective stress shadow behind the propagating fracture tips, where the granular pack exhibits undrained behavior. We conceptualize the behavior of the system by means of a mechanistic model for a wedge of the granular pack bounded by two growing fractures. The model captures the pore-pressure build-up inside the stress shadow region and the grain compaction in the annular region outside. Our model reveals that a jamming transition determines the distinct rheological behavior of the wet granular pack, from a friction-dominated to an elasticity-dominated response.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC)
• Grant/Contract Number: SC0018357
• OSTI ID: 2420773
• Journal Information: Physical Review Applied, Journal Name: Physical Review Applied Journal Issue: 6 Vol. 18; ISSN 2331-7019
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Physics