This experiment aims at researching the change regulation of soil stability under the condition of dry-wet cycles of all layers of soil in collapsing gully erosion area where granite develops. By conducting the experiment of dry-wet cycles for typical development of all layers of the soil (eluvial horizon

illuvial horizon

cambic horizon and parent material horizon) of granite slope in collapsing gully erosion area in Tongcheng

Hubei province

we analyzed the influence of the times of dry-wet alternations on the development of soil cracks

the disintegration characteristics of soil and the shear strength of soil of all soil layers. The results showed that: under the influence of dry-wet cycles

the soil developed cracks gradually; after the second cycle

main cracks arised

and the crack ratio increased significantly; after that

cycles developed small cracks. After 4 times of dry-wet alternations

the size of the crack ratio of the 4 layers of soil listed as illuvial horizon＞eluvial horizon＞cambic horizon＞parent material horizon. With the increasing times of dry-wet cycles

soil cracks developed

soil disintegration characteristics of all layers of soil increased constantly

and the disintegration of eluvial horizon and illuvial horizon was slow

while cambic horizon and parent material horizon could completely collapse in a very short time; With the increasing times of dry-wet cycles

the shear strength of soil attenuated constantly

and the amplitude attenuation of eluvial horizon and illuvial horizon decreased

while the amplitude attenuation of cambic horizon and parent material horizon increased.