Physical Modelling of Flowslide Mobility
Davoodi Bilesavar, Roya
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Static liquefaction is a sudden decrease of soil shear strength due to the rapid development of pore pressures generated during the collapse of loose, saturated soil deposits. If this type of failure occurs in sloping soils, a flowslide can result. Viscous debris moving down a slope with high velocity could cover a vast area and cause significant loss of life and property. The primary objective of this study was to investigate the triggering factors of liquefaction in shallow slopes through the physical modeling technique of centrifuge testing. A flowslide simulator was developed to investigate the factors that lead to the liquefaction of soil slopes. This simulator was capable of replicating groundwater regimes and intense rainfalls with pore pressure transducers to monitor the pore pressure changes in the model slope and digital cameras to calculate the resultant slope deformation, velocity, and acceleration using the Particle Image Velocimetry method (PIV) of digital image correlation. In the course of this research, four centrifuge tests have been performed to evaluate the triggering mechanisms of fast landslides in shallow slopes. A seepage induced failure was simulated in the first test. The second and third tests were conducted applying different groundwater regimes in combination with intense rainfall to bring the slope to failure. The last test was a rainfall induced failure in the absence of a pre-existing groundwater table. The results from these experiments illustrate that the initial groundwater level has a considerable effect on the mobility of flowslides.