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.
List of notations
R roundness of soil particle
Swl s phericity of soil particle
emax maximum void ratio of soil
emin minimum void ratio of soil
γmax maximum dry unit weight of soil
γmin minimum dry unit weight of soil
Wp width of patterns
Lp profile length
Rmicro micro-roughness
Rmaxmaximum roughness
Rn normalised roughness
τ shear stress
σn normal stress
Φf angle of internal friction
δf interface friction angle
ψ dilation angle
dh horizontal displacement
dv vertical displacement
δp peak interface friction angle
δu ultimate interface friction angle
ILR interaction length ratio
Li 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
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.