Abstract: The indoor slope model tests were conducted to investigate the deformation, water infiltration and failure characteristics of an expansive rock slope under different types of precipitation. Significant horizontal displacement was found under the initial rainfall in continuous rainfall mode, whereas the later deformation was small and tended to be stable. The peak values of displacement and deep rock moisture content were reached at a period of time after rainfall ceased. With the increase of cycle number and rainfall, the slope deformation and the deformation rate increased significantly, and the rock fissures developed further, resulting in an increase in water infiltration depth. This was observed in the soil layer close to the ground surface, but not in the deep rock. The experimental results imply that, due to initial large swelling-induced deformation in the continuous rainfall mode, the drainage and protective measures should be enforced and improved; in the wet-dry cycles mode, the anti-seepage measures for slope surface should be improved to resist the infiltration of rain with the increase of cycle number. In additional, the typical circular sliding failure of purely expansive rock slope was not found in aforementioned two rainfall modes in the tests. However, the engineering slope failure often occurs in the weak interlayer. Therefore, further investigation into the weak interlayer in expansive rock slope should be conducted , and for the mudstone slope without weak interlayer, more attention should be paid to monitoring the shallow deformation characteristics.

Key words: expansive rock, slope, continuous rainfall, wet-dry cycles, deformation, volumetric moisture content, model test