Effect of snakeskin-inspired patterns on the shear response of soil - continuum interfaces

ABSTRACT

The interface shear responses of soils and 3D printed continuum surfaces with patterns inspired by three distinctive snake-scale morphologies are studied. Interface shear tests are conducted under low normal stresses in cranial (where soil shears against the scales) and caudal (where soil shears along with the scales) directions. The experiments show that the snakeskin-inspired surfaces with different heights and shapes of the scales exhibit different shear responses and mobilize frictional anisotropy (difference in peak interface friction angles) in the range of 3–9 degrees. In the cranial direction, all the snakeskin-inspired patterns mobilize the peak internal friction angle of the neighbouring soil at the interface after a critical normalized roughness of the surfaces. Further, the snakeskin-inspired patterns exhibit significant strain-softening behaviour in comparison to an unpatterned surface. Rounded soil particles exhibit a lower frictional resistance and stick-slip phenomenon in the post-peak interface shear response, unlike angular soil particles.

KEYWORDS:

• Snakeskin-inspired patterns
• 3D printed surfaces
• frictional anisotropy
• soil-continuum material interface
• interface shear behaviour
• particle shape

List of notations

R roundness of soil particle

S_wl s phericity of soil particle

e_max maximum void ratio of soil

e_min minimum void ratio of soil

γ_max maximum dry unit weight of soil

γ_min minimum dry unit weight of soil

W_p width of patterns

L_p profile length

R_micro micro-roughness

R_maxmaximum roughness

R_n normalised roughness

τ shear stress

σ_n normal stress

Φ_f angle of internal friction

δ_f interface friction angle

ψ dilation angle

d_h horizontal displacement

d_v vertical displacement

δp peak interface friction angle

δ_u ultimate interface friction angle

IL_R interaction length ratio

L_i length of interaction

D₅₀ mean diameter of the soil particle

η efficiency parameter

Acknowledgments

The work is supported by the Science and Engineering Research Board (SERB), India (Project code: SRG/2019/000561).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data Availability Statement

The URL of data that support the findings of this study are available from the corresponding author, [Prashanth Vangla], upon reasonable request.

Additional information

Funding

This work was supported by the Science and Engineering Research Board [SRG/2019/000561]. .

Notes on contributors

V.L. Gayathri

V.L. Gayathri is currently a PhD candidate at Indian Institute of Technology (IIT) Delhi. Her areas of interest are snakeskin-inspired patterns for geotechnical applications, soil-continuum interface behaviour and digital image correlation for deformation analysis. She holds a Master of Technology (M.Tech) degree in Geotechical Engineering from National Institute of Technology (NIT), Warangal and Bachelor of Technology (B.Tech) degree in Civil Engineering from the University of Kerala, India.

Prashanth Vangla

Prashanth Vangla is an Assistant Professor in the Department of Civil Engineering at Indian Institute of Technology Delhi, where he has been since 2018. From 2017 to 2018, he worked as a postdoctoral researcher at Georgia Institute of Technology, USA. He received his Ph.D. in Civil Engineering from the Indian Institute of Science Bangalore in 2017. Master of Technology in Geotechnical Engineering from Indian Institute of Technology Guwahati, India, in 2011. From 2008 to 2009 worked as a site engineer with Gammon India Ltd for a dam and tunnel construction project. He received a B.E. degree in Civil Engineering from Vasavi College of Engineering in 2008. Recipient of several national and international awards, namely IGS-Prof. Leonard’S Biennial Award best Ph.D. Thesis and Best Paper Award in Eighth Asian Young Geotechnical Engineers Conference.

Anilkumar Riya

Riya Anilkumar is currently a PhD student at the University of California Davis. Her research interests are bio-inspired probes for subsurface characterization, snake-inspired patterns for geotechnical applications, the use of biopolymers for soil improvement and 3D particle shape characterization methods. She obtained her Bachelor of Technology (B.Tech) degree from the Indian Institute of Technology Delhi.