Experimental study on the coupled behavior of dynamic cracking and moisture-heat evolution of a clay under evaporation

A clay is prone to shrinkage and cracking under evaporation, which can cause vast hazards in geotechnical and geo-environmental engineering. Knowledge of the coupled behavior of dynamic cracking and moisture-heat evolution is helpful for better understanding the mechanical performance of a clay under evaporation. An evaporation experiment was conducted on a clayey soil specimen in this study, accompanied by observation of shrinkage and cracking and monitoring of moisture-heat. In this way, the fully coupled behavior of shrinkage, cracking, and moisture-heat evolution of the clay under evaporation was investigated. The results show that the clay loses most of its water and achieves most of the shrinkage before the latter evaporation stage. Especially in the intermediate evaporation stage, the soil saturation has a quick reduction, the soil suction has a linear increase, and the soil temperature has a sharp rise. Because of this moisture-heat evolution, both the degree of the nonuniform shrinkage and the increased rate of the crack ratio and the crack depth reach the maximum values. Along with the crack developing downward and bringing new air-entry channels, the actual evaporation front also moves downward. The evaporation from the surface-exposed crack can significantly affect the moisture-heat evolution of the clay. The crack can develop further to the width and the depth owing to the nonuniform shrinkage existing at the different locations and the different depths of the clay. The nonuniform shrinkage may be attributed to the heterogeneity of the soil properties, the inhomogeneous evaporation environment, and the huge difference of moisture-heat characteristics of the clay.