Boundary Effects in the Desiccation of Soil Layers with Controlled Environmental Conditions

Abstract

This article presents the results of an experimental research carried to investigate the mechanics of cracking of soil layers under drying conditions. The tests were conducted under controlled laboratory conditions and in an environmental chamber with circular and rectangular specimens to investigate the effect of the boundary conditions (size, shape, and aspect ratio of the specimens and containers) on the process of initiation and propagation of cracks and on the final crack pattern at the end of desiccation. The tests in the environmental chamber were conducted with imposed temperature and relative humidity and provided new insight into the mechanics of the formation of cracks in a drying soil, and they showed that cracks can initiate either at the top, bottom, or at both surfaces of the drying specimen. The results also reveal how the crack patterns are controlled by the existing mechanical and hydraulic boundary conditions. The cracks seem to form sequentially in patterns that can be explained by three key factors: stresses higher than the tensile strength, the direction of the generated stresses, and the stress redistribution in the vicinity or inside the newly formed domain. In order to substantiate the sequential nature of the crack pattern formation, experimental evidences showing the existence of a cracking sequence during the laboratory desiccation experiments are presented and analyzed.

Drought‐Induced Soil Desiccation Cracking Behavior With Consideration of Basal Friction and Layer Thickness

“…It should be noted that there is an increase in N T with decreasing layer thickness, representing that the number of cracks initiating at the top surface reduces. This effect of layer thickness on soil surface cracking observed in this study is consistent with the results obtained by previous researchers (Costa et al, 2013; Gui et al, 2016; Guo et al, 2018; Lakshmikantha et al, 2012; Lakshmikantha et al, 2018; Zeng et al, 2019). N B gradually exceeds N T as the layer thickness increases, indicating that more cracks develop from the bottom surface.…”

“…The frictional force generated on the base between soil interlayers applies a significant constraint to the upper soil shrinkage and causes the soil desiccation cracking. In previous studies, some scholars found that the basal friction could affect the stress distribution inside the soil and aggravate soil cracking (Amarasiri & Kodikara, 2013;Gui et al, 2016;Guo et al, 2018;Lakshmikantha et al, 2018;Pouya et al, 2018;Rodríguez, 2006;Sima et al, 2014;Vo et al, 2017;Zeng et al, 2019). So far, most prior studies focus on the evolutions of desiccation cracks initiated at the soil top surface.…”

“…Soil cracking is a complex process sensitive to environmental, intrinsic, and boundary factors such as atmospheric temperature (Tang et al, 2010), mineral content (Albrecht & Benson, 2001; Kalkan, 2009), soil size (Costa et al, 2013; Shorlin et al, 2000), and salinity (DeCarlo & Shokri, 2014a). As a generally accepted view, one of the main cracking mechanisms is that when soil desiccation shrinkage is constrained, the concentrated tensile stress inside the soil exceeds its tensile strength (Corte & Higashi, 1960; DeCarlo & Shokri, 2014b; Groisman & Kaplan, 2007; Kodikara & Costa, 2013; Lakshmikantha et al, 2018; Péron et al, 2009). The stress concentration can be induced by different factors such as heterogeneities in soil structure and the constraint of soil boundaries.…”

Desiccation Cracking Behavior of MICP-Treated Bentonite

“…Literature reviews indicate that using different materials (e.g., glass, wood) as the soil mold influences the size of the desiccated soil clods [34]. Smooth contact surfaces result in smaller width and spacing of the cracking [35], whereas rough interfaces lead to larger extent of cracking and wider crack width distributions [36]. Although the interface roughness was not characterized in this study, we examined the repeatability of the test by comparing results obtained from three parallel samples.…”

Studying the effect of desiccation cracking on the evaporation process of a Luvisol – From a small-scale experimental and numerical approach

“…In the past few decades, desiccation cracking in soil has been widely studied by using both experimental and numerical approaches. Different types of environmental chamber were designed to study cracking in soils as a result of drying/wetting conditions by imposing and monitoring temperature and relative humidity (Cui et al, 2014;Song et al, 2016;Lakshmikantha et al, 2018). Recently, Lozada et al (2018) have presented an advanced climatic chamber which is able to provide accurate and independent control of temperature, relative humidity, solar irradiance, and wind velocity.…”