Abstract:The movement of translational landslides was controlled by the bedding parallel to the shear zone in the Neogene soft rock, in which the distribution of clay minerals determined whether the landslide could slide along a lowangle zone. In order to analyze the aggregation law of clay minerals in bedding parallel shear zone, the composition, structure, clay mineral content and stress properties of six representative geological sections were quantitatively tested. It is found that the structure of bedding parallel to the shear zone shows fragmentation, cleavage, plasticization and mud. The cumulative displacement at the upper boundary of the shear zone is the largest, while the cumulative displacement at the middle and bottom boundary planes decreases gradually. The material composition, hydraulics, and mechanical properties of mudstones at the above three locations change synergistically. Taking Bojishan landslide as an example, the contents of clay particles on upper boundary, middle shear planes and bottom boundary are 62. 60%, 62. 46% and 58. 04%, respectively, and the water content is 28. 82%, 25. 34%, 25. 52%. The dilatancy mechanism in shear zone controls the coupling process between water and soft rock.