Abstract：By the field tests as well as tests conducted on the self-developed disintegration instrument，the disintegration of loess is studied. Results show that the disintegration procedure includes fragmentation process， breaking process，and separation process. Firstly，the characters of the three processes are generalized. The point of view is put forward that both the fragmentation process and the breaking process are instantaneous and non-reversible，while the separation process takes some time and is reversible to some extent. Secondly，the mechanism of influence of natural water content and loess structure on the disintegration are analyzed，which suggests that the time effect of the loess disintegration is caused by the velocity of humidification. That is，the disintegration process goes more quickly with the increase of natural water content of the loess，resulting in the thickening of water film surrounding the particles as well as the decrease of the swelling energy. Finally，the boundary effects of disintegration are mainly studied. Results show that the origin of the disintegration nucleus is the slow moistening of the penetration process of the inner layer caused by the temporary boundary confining of the outer penetration layer. Results obtained from the field tests indicate that the boundary effect becomes more obvious with the decrease of the depth of water and the increase of curvature of the slot surfaces，and the sharpening of the edges of the convex upright field samples. The reasons of finiteness and edging effects of disintegration are explained logically.
