Investigating the Potential of Infrared Thermography to Inform on Physical and Mechanical Properties of Soils for Geotechnical Engineering

0564750 - ÚSMH 2023 RIV CH eng J - Journal Article
Loche, M. - Scaringi, G. - Blahůt, Jan - Hartvich, Filip
Investigating the Potential of Infrared Thermography to Inform on Physical and Mechanical Properties of Soils for Geotechnical Engineering.
Remote Sensing. Roč. 14, č. 16 (2022), č. článku 4067. E-ISSN 2072-4292
Institutional support: RVO:67985891
Keywords : infrared thermography * cooling rate index * porosity * critical state friction angle * empirical correlation * soil mechanics
OECD category: Geology
Impact factor: 5, year: 2022
Method of publishing: Open access
https://www.mdpi.com/2072-4292/14/16/4067

Knowledge of physical and mechanical properties of geomaterials is fundamental to
characterise their response to external forcings (mechanical, climatic) at various scales. This is true, for
instance, in slope stability assessments, civil engineering works, and agriculture. The direct evaluation
of these properties in situ can be difficult, especially in inaccessible or vast areas, and so can be the
sampling and subsequent testing in the laboratory—where ensuring the representativeness of the
acquired data at the scale of analysis poses an additional challenge. Thus, empirical correlations with
more readily determinable quantities remain a powerful and practical tool. Recently, several sensors,
able to inform on various geomaterial properties, have been developed. However, applications have
typically targeted rocks, while studies on uncemented geomaterials (soils, geotechnically speaking)
are lacking. Here, we propose a simple method to evaluate the porosity and critical state friction
angle of soils via infrared thermography, consisting of periodic acquisitions of images in infrared
wavelengths. To demonstrate the method’s capability, we analysed the cooling behaviour of samples
of bentonite, kaolin, and sand (for which an extensive characterisation exists in the literature), after
compaction to different porosities and pre-heating in an oven. We interpreted the results by seeking
the optimal time interval for which a cooling rate index (CRI) could be defined, which is best linked
with the target property. We found that the CRI correlates very well with the critical state friction
angle (R2 > 0.85) and that different materials show unique and strong (R2 = 0.86–0.99) relationships
between their porosity and the CRI, which also varies in a material-specific fashion according to
the explored time interval. Although a systematic investigation on a wide range of natural soils
is warranted, we argue that our method can be highly informative and could be used to calibrate
remote sensing-based full-scale implementations in situ for various purposes.

Permanent Link: https://hdl.handle.net/11104/0336374