Investigation of desiccation cracks in drying soil
PublisherUniversity of Strathclyde
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This research investigates desiccation cracking behaviour of a fill material from a flood embankment along the Bengawan Solo River in East Java, Indonesia, an area that is prone to extremes in flooding and drying. A detailed study of the previous works on this topic showed the absence of fully-monitored laboratory tests dedicated to desiccation cracking behaviour. This study combined traditional and new techniques to characterise desiccation cracking behaviour in this material in a suite of laboratory tests. Desiccation plate tests were conducted to gain basic knowledge of the cracking behaviour of Bengawan Solo soil and identify the influences of plate shape on test results. Crack initiation, evolution, and final pattern were studied in detail. Results of the experiments showed that plate geometry had minimal effect on cracking behaviour except for the final cracking pattern. Crack initiation and evolution was characterised with a 2D/3D profile laser sensor coupled to a motion controller that allowed scanning of the overall surface of the drying soil. The system developed for this work was used to track the three most relevant variables associated with the behavior of soils during desiccation: volume change, water loss, and evolving crack network morphology. With this new method, the evolution of crack aperture, crack depth, surface contour levels (settlements) and evolution of global volume change were captured in real time, significantly improving upon previous methods for crack monitoring. Finally, the effects of moisture content and dry density on tensile strength during cracking was investigated at two states: reconstituted and compacted. Microstructural investigation illustrated the fabric changes during drying at two states to complement the experimental results for tensile strength. The comparison of tensile strength between reconstituted and compacted state has been found promising and believed to be useful in earthwork construction projects.