{"title":"Understanding the mudcrack patterns: How layer thickness, grain size, and secondary layers affect their formation – A laboratory study","authors":"Tushar Todkar, Puspendu Saha, Santanu Misra","doi":"10.1007/s12040-024-02337-9","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This paper investigates the initiation and evolution of polygonal crack patterns in desiccating soil layers with varying thicknesses and grain sizes, both with and without a secondary saturated sand layer placed beneath the soil layer. Single-layer experiments involved soil samples within a specific range of grain sizes (0–100, 100–300, 300–500, and 500–850 μm), maintaining soil layer depths at 10, 20, 30, 40, 50, and 60 mm. In double-layer experiments, a saturated sand layer was introduced below the soil layer to check the role of relative layer thickness on crack patterns. Time-lapse photography captured surface crack development during desiccation, allowing for the measurement of geometric parameters like crack width, crack intensity factor (CIF), and intersection angle (CIA). The single-layer models indicate an increase in crack width and CIF with greater layer thicknesses, while CIA decreases with increased layer thickness. Additionally, experiments with finer grain sizes exhibit relatively wider cracks, along with higher CIF and CIA. In double-layer models with varying thicknesses of individual layers, crack growth is found to be independent of the upper soil layer's thickness. Instead, crack propagation is controlled by the lower sand layer, as the supply of water from the lower sand layer to the upper soil layer facilitates prolonged desiccation, resulting in larger CIF values. Using digital image processing and the box-counting method, we calculated the fractal dimensions (<i>D</i>) of the cracks were calculated. <i>D</i> demonstrates positive relationships with grain size in both single- and double-layer experiments, suggesting a self-similar evolution of crack patterns in the models with coarse-grained soil.</p><h3 data-test=\"abstract-sub-heading\">Research highlights</h3>\n<ul>\n<li>\n<p>The role of basal water-rich sand layer in the growth of mud-cracks is investigated.</p>\n</li>\n<li>\n<p>Layer thickness and grain size are two additional variables during the experiments.</p>\n</li>\n<li>\n<p>Single mud-layer experiments were used to compare the double-layer experiments.</p>\n</li>\n<li>\n<p>Basal wet-sand delays desiccation, resulting in a higher crack intensity factor.</p>\n</li>\n<li>\n<p>Finer grains produce denser cracks irrespective of the imposed variables.</p>\n</li>\n<li>\n<p>Low fractal dimensions in course-grained soils imply a self-similar crack pattern.</p>\n</li>\n</ul>","PeriodicalId":15609,"journal":{"name":"Journal of Earth System Science","volume":"151 1","pages":""},"PeriodicalIF":1.3000,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Earth System Science","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s12040-024-02337-9","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
This paper investigates the initiation and evolution of polygonal crack patterns in desiccating soil layers with varying thicknesses and grain sizes, both with and without a secondary saturated sand layer placed beneath the soil layer. Single-layer experiments involved soil samples within a specific range of grain sizes (0–100, 100–300, 300–500, and 500–850 μm), maintaining soil layer depths at 10, 20, 30, 40, 50, and 60 mm. In double-layer experiments, a saturated sand layer was introduced below the soil layer to check the role of relative layer thickness on crack patterns. Time-lapse photography captured surface crack development during desiccation, allowing for the measurement of geometric parameters like crack width, crack intensity factor (CIF), and intersection angle (CIA). The single-layer models indicate an increase in crack width and CIF with greater layer thicknesses, while CIA decreases with increased layer thickness. Additionally, experiments with finer grain sizes exhibit relatively wider cracks, along with higher CIF and CIA. In double-layer models with varying thicknesses of individual layers, crack growth is found to be independent of the upper soil layer's thickness. Instead, crack propagation is controlled by the lower sand layer, as the supply of water from the lower sand layer to the upper soil layer facilitates prolonged desiccation, resulting in larger CIF values. Using digital image processing and the box-counting method, we calculated the fractal dimensions (D) of the cracks were calculated. D demonstrates positive relationships with grain size in both single- and double-layer experiments, suggesting a self-similar evolution of crack patterns in the models with coarse-grained soil.
Research highlights
The role of basal water-rich sand layer in the growth of mud-cracks is investigated.
Layer thickness and grain size are two additional variables during the experiments.
Single mud-layer experiments were used to compare the double-layer experiments.
Basal wet-sand delays desiccation, resulting in a higher crack intensity factor.
Finer grains produce denser cracks irrespective of the imposed variables.
Low fractal dimensions in course-grained soils imply a self-similar crack pattern.
期刊介绍：
The Journal of Earth System Science, an International Journal, was earlier a part of the Proceedings of the Indian Academy of Sciences – Section A begun in 1934, and later split in 1978 into theme journals. This journal was published as Proceedings – Earth and Planetary Sciences since 1978, and in 2005 was renamed ‘Journal of Earth System Science’.
The journal is highly inter-disciplinary and publishes scholarly research – new data, ideas, and conceptual advances – in Earth System Science. The focus is on the evolution of the Earth as a system: manuscripts describing changes of anthropogenic origin in a limited region are not considered unless they go beyond describing the changes to include an analysis of earth-system processes. The journal''s scope includes the solid earth (geosphere), the atmosphere, the hydrosphere (including cryosphere), and the biosphere; it also addresses related aspects of planetary and space sciences. Contributions pertaining to the Indian sub- continent and the surrounding Indian-Ocean region are particularly welcome. Given that a large number of manuscripts report either observations or model results for a limited domain, manuscripts intended for publication in JESS are expected to fulfill at least one of the following three criteria.
The data should be of relevance and should be of statistically significant size and from a region from where such data are sparse. If the data are from a well-sampled region, the data size should be considerable and advance our knowledge of the region.
A model study is carried out to explain observations reported either in the same manuscript or in the literature.
The analysis, whether of data or with models, is novel and the inferences advance the current knowledge.
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