Infiltration is critical to the redistribution of rainfall in a collapsed wall and directly affects its gravity erosion process. In this study

the experiment designed six dry-wet cycles

and through saturated infiltration experiments of four layers of soil fissures and digital image processing technology

the evolution of four layers of soil fissures under the effect of dry-wet cycles and its influence on saturated soil permeability of each soil layer were studied. The results showed that: (1) With the increasing of the wet and dry cycles

the fissures in the topsoil layer and the laterite layer developed obviously

the fissure rate gradually increased and then tended to be stable

while the transition layer and sand layer had almost no fissures. The fissures of the topsoil were almost completely developed after the third cycle

and the fissure rate reached 3.50%. The fissures were slender and broken. However

for the laterite

after the first cycle

the fissures were basically fully fixed

the fracture width would remain unchanged when it increased to a certain extent with the progress of the dry-wet cycle. (2) The soil permeability coefficient of the four layers followed the order of sandy soil layer > transition layer > laterite layer > topsoil layer. With the increasing of the number of wet and dry cycles

the permeability coefficients of the topsoil layer and the laterite layer gradually increased and then tended to be stable

the transition layer was relatively stable

and the sand layer gradually decreased and then tended to be stable. (3) There was a quadratic function relationship between the soil fissure rate and the permeability coefficient. The impact of fissure development on soil permeability increased first and then decreased. The results could provide a scientific basis for the study of the mechanism of wall collapse instability under rainfall infiltration and redistribution.