Airblast evolution initiated by Wangjiayan landslides in the Ms 8.0 Wenchuan earthquake and its destructive capacity analysis

Abstract

Airblasts, as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches, commonly result in catastrophic damages and are attracting more and more scientific attention. To quantitatively analyze the intensity of airblast initiated by landslides, the Wangjiayan landslide, occurred in the Wenchuan earthquake, is selected here with the landslide propagation and airblast evolution being studied using FLUENT by introducing the Voellmy rheological law. The results reveal that: (1) For the Wangjiayan landslide, its whole travelling duration is only 12 s with its maximum velocity reaching 36 m/s at t=10 s; (2) corresponding to the landslide propagation, the maximum velocity, 28 m/s, of the airblast initiated by the landslide also appears at t=10 s with its maximum pressure reaching 594.8 Pa, which is equivalent to violent storm; (3) under the attack of airblast, the load suffered by buildings in the airblast zone increases to 1300 Pa at t=9.4 s and sharply decreased to –7000 Pa as the rapid decrease of the velocity of the sliding mass at t=10 s, which is seriously unfavorable for buildings and might be the key reason for the destructive collapse of buildings in the airblast zone of the Wangjiayan landslide.