Study on the dynamic mechanism of soil desiccation cracking by surface strain/displacement analysis.

Digital camera was used to record the dynamic process of soil desiccation cracks in real time. With application of image processing technique, the relationship between the strain/displacement field and desiccation cracking were analyzed. Results show that the crack usually occurs at locations where tensile strain concentrates. After the crack is generated, the surrounding strain field and displacement field are rapidly redistributed. The new strain field and displacement field act on the crack again, affecting the propagation direction of the crack. Under the interaction between the strain/displacement field and cracks, the crack tends to intersect with other cracks at right angles and deflection may occur in the development process. The soil is divided into different clods by the cracks. Each clod centripetally shrinks and has a shrinkage center which may move with elapsed drying time. Based on the strain/displacement field, the characteristics of desiccation cracking in local area of soil can be predicted in advance and it can be used to directly judge the activeness of the cracks or clods. The digital image processing technique can effectively obtain the soil deformation without disturbing the soil sample, which offers an available way for understanding the intrinsic dynamic mechanisms of soil desiccation cracking. [ABSTRACT FROM AUTHOR]