Abstract: Water level fluctuation has induced a large number of slope failures, resulting in huge losses of life and property. Clarifying the failure mechanism is a requisite for a reasonable evaluation on slope safety under water level fluctuation condition. Such mechanism was investigated using centrifuge model tests in the present research. Test results demonstrate that water level fluctuation gave rise to local failure in the mid-lower part of the slope which developed upwards until the final slip surface was formed. The accumulation of local deformation, instead of instantaneous destruction, is the fundamental cause of slope failure under water level fluctuation. The local deformation developed monotonically and further triggered new local deformations around and extended in the slope. In summary, the extinct coupling of local deformation accumulation and failure process under water level fluctuation should be well considered in the analysis of slope failure.

Key words: soil slope, local deformation, water level variation, centrifuge model test, failure mechanism