CENTRIFUGE MODEL TEST STUDY OF RAINFALL-INDUCED DEFORMATION OF COHESIVE SOIL SLOPES

A rainfall simulation device was developed to realize uniform rainfall at high g-levels in centrifuge model tests. A series of centrifuge model tests was conducted on cohesive soil slopes during rainfall, and the displacement and suction of the slopes were measured. The slope exhibits a relatively shallow slide after a heavy rainfall, and exhibits a shear zone with significant deformation in the interior of the slope. The vertical displacement is significantly larger than the horizontal displacement of the slope during rainfall. The rainfall-induced displacement process can be divided into three phases: (1) small displacement, (2) rapid increase, and (3) large displacement with minor rate of increase. Strain analysis was conducted on the basis of the measured displacement, and the results showed that the rainfall-induced deformation of the slope is governed by two types of mechanisms: increasing overburden weight and softening of soil. For a point in the slope, the first mechanism occurs from the beginning of rainfall; and the second mechanism occurs only when the water infiltrates there, which is described using the wetting front. Accordingly, another term, stable front, describes a boundary of zero increment of deformation. These two fronts gradually advance into the slope with increasing rainfall and divide the slope into three zones. The middle zone exhibits the most significant deformation.