Abstract: At 15:00 PM on October 3, 2009, the 260×104 m3 of the pile-stabilizing fill slope slid suddenly in Panzhihua airport in Southwest China, so as to reactivate the Yijiaping landslide located at the downside of the fill slope and cause 2 years interruption of Panzhihua airport. Sliding mechanism of the pile-stabilizing fill slope under rainfall conditions is studied using a centrifuge modeling technique. A series of centrifuge tests on the reinforced model are conducted respectively during different accelerations under natural and rainfall conditions, reproducing the slide process of the fill slope. The analysis of the centrifuge model test results is performed to investigate the sliding mechanism of the landslide. Under natural condition, deformation of the slope includes crest settlement and creep of soft layer mainly; and the slope appears creep state. Under rainfall and groundwater conditions, tensile fracture of rear and compressive failure of front are obvious; and the slope shows progressive break characteristic and slides finally. The piles in the slope stressed larger, and the closer pile to the rear end of the slope, the larger the pile’s pushing force, which causes the progressive failure of piles from rear to front. The irrational pile spacing among three rows of piles may account for the incapability of piles in retaining the slope. It can be concluded that the occurrence of slope failure is contributed to the soft layer at the soil-rock interface and the high pore pressure in rainfall condition, which is found to be 3.7 times the pore pressure under natural condition. Comparing the model test with the prototype test, the sliding mechanism of the fill slope can be recognized as shear creeping-progressive breaking-sliding mode.

Key words: high fill slope, stabilizing pile, centrifugal model test, sliding mechanism