Experimental investigation into cracking behavior and shear strength deterioration of jute fiber-reinforced red clay under wetting-drying cycles

Abstract: To investigate the cracking resistance and shear strength deterioration of jute fiber-reinforced red clay under wetting–drying cycles, six fiber volume fractions (0%–1.0%) were tested over five wetting–drying cycles, and the crack evolution and strength parameters were analyzed by digital image processing and direct shear tests. At 1.0% fiber content, the average crack width and crack intensity factor (CIF) were reduced by 63.0% and 45.0%, respectively, relative to the plain soil. Crack inhibition improved more rapidly over the 0.6%–0.8% range, and the fiber restraint mode was tentatively considered to shift from localized to distributed restraint. Cohesion exhibited a two-stage degradation, decreasing rapidly during the first three cycles and then stabilizing; the attenuation rate fell from 30.7% in the plain soil to 18.0% at 1.0% fiber content, whereas the internal friction angle was only slightly affected. Crack closure during the wetting phase was accompanied by particle migration, exhibiting shallow self-healing characteristics. The desiccation cracking process can be divided into three stages: stress accumulation, crack initiation, and crack network stabilization. These mechanistic interpretations are inferred from macroscopic observations and require microstructural verification. The findings provide experimental support for the ecological stabilization and long-term durability assessment of red clay slopes.