Study on crack propagation and shear behavior of weak muddy intercalations submitted to wetting-drying cycles

This study addresses the crack evolution law and shear behavior of weak muddy intercalations (WMIs) during wetting-drying cycles. The original crack images of WMI were processed; adjustments were made to overcome the reflective differences of crack on the surface of the WMI samples caused by the uneven surface and impurities, effectively distinguishing the crack and non-crack areas in the images of the WMI sample surface. In addition, the total length, average width, area ratio, and number of cracks were extracted as the index represents the crack condition of the WMI sample surface. Shear testing on surface of the WMI sample was used to analyze the shear properties for different wetting-drying cycles, and the relationships between crack propagation and shear properties in the wetting-drying cycles were considered. The results show that the wetting-drying cycles elongate crack on the surface of the WMI sample. The average widths of the cracks also increase, and a large number of new tensile cracks are generated. As a result, the crack degree increases with the wetting-drying cycles. Crack propagation could also weaken the WMI structure as the development of the crack may reduce the tight contact points between WMI particles, leading to decreased cohesion in the WMI. As for the shear behavior of the WMI, the shear strength may decline with the wetting-drying cycles but tends to stabilize after a certain number of cycles.