Centrifugal model test study on macro-micro mechanism of slope instability caused by rainwater infiltration
To explore the rainfall infiltration characteristics and the macro-micro mechanism of rainfall-induced slope instability,three centrifugal modeling tests were conducted under different rainfall intensities for two types of test slopes,respectively,which have different permeabilities(i.e.,test slopes prepared with quartz sand and fine sand).During the tests,the wetting front migration characteristics,the failure mode,and the particle movements in specific areas of the slope were observed and recorded,and the variations of pore water pressure at different positions of the slope were monitored.The test results showed that:(1)During rainfall,the wetting front in the slope migrates to the deeper regions in the form of an elliptic arc,and its migration rate is fast at the beginning but reduces thereafter.With the increase in rainfall intensity or permeability,the wetting front migration rate also increases.(2)The different failure modes of slopes with different permeability result from the different modes of fine particle migration and loss and the different locations of high-water content areas.(3)The pore water pressure growth mode is different in slopes with different permeabilities.When the permeability coefficient of the slope is small,the pore water pressure varies in type Ⅰ with a single steep rise followed by a sharp drop;When the permeability coefficient of the slope is large,the pore water pressure varies in type Ⅱ with multiple rises and drops.(4)Different pore water pressure growth modes lead to different failure modes of the slope,and the slope k of the peak point line of pore water pressure is introduced to represent the integrity of slope failure.When the pore water pressure growth mode is type Ⅰ,k is larger and the slope slides as a whole.When the pore water pressure growth mode is type Ⅱ,k is small and the slope slides in the progressive failure mode.The results of this study can provide an experimental basis for the prevention and control of rainfall-induced landslides.
slope engineeringwetting frontpore water pressurecentrifugal model testfailure modeseepage characteristics
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