Abstract: The relationship between the development of cracks and the strength of the original and the remolded red clay in Guizhou under the action of dry-wet cycles are studied in this paper. The mechanical indicators are obtained through dry-wet cycle tests and direct shear tests. The particles (pores) and fracture images are used to identify. The analysis system (PCAS) processes the image and analyzes the fracture index. The results show that: (1) the degree of fissure development of the undisturbed soil is higher than that of the remolded soil; (2) as the number of cycles increases, there is a positive correlation between the surface crack rate, the number of cracks, and the total length of fissures in undisturbed soil samples. The development of soil cracks does not change much with the number of cycles; (3) The number of cycles has an impact on the integrity of the damaged soil samples, and there is an inflection point value for the number of cycles (3-4 times), indicating that the dry-wet cycles only affect the soil under a certain number of times. The development of the sample fissures will have an impact, and the fissures in the soil sample will not increase due to the increase in the number of cycles. In addition, the mechanical properties of the reshaped red clay samples are lower than that of the original red clay. The cohesion of the original red clay decreases with the development of cracks, and the change of the cohesive force of the remolded red clay is less affected by the development of cracks. The angle of the internal friction all increased slightly.

Key words: Red Clay, Dry-Wet Cycle, Crack Image Characteristics, Shear Strength