Abstract: The research on the fracture characteristics of the expansive soil is the foundation of the fracture research. Qualitative and quantitative description of the development of fissures can further understand the properties of expansive soil. The development and present situation of micro measurement methods of expansive soil are discussed, and the commonly used micro measurement methods are summarized. The conclusions are as follows: (1) Although there are many quantitative analyses, it is mainly qualitative analysis, quantitative index and system need to be improved and the relationship between microstructure and mechanics needs to be improved. (2) The influencing factors of the formation of the cracks in expansive soil are introduced. (3) The direct observation method, the indirect observation method and the statistical analysis method about the fracture microstructure of the expansive soil are summarized.

Key words: Expansive Soils, Fracture, Micro Measurement Methods, Image Processing, Research Progress