In order to study the intensity and the variation law of the airblast induced during the high-speed motion of rock avalanche with multiple angle changes along its travelling path

a true three-dimensional model of the Niujuangou rock avalanche is studied with the software CFD by introducing the definition of resistance along traveling path under the law of Voellmy. The characteristic of the airblast flow field is simulated emphatically with the dynamic mechanism of the airblast discussed based on the back-analysis of the whole travelling process of the Niujuangou rock avalanche. The results show: (1) The whole travelling process of the sliding mass lasts 119 s

and the maximum speed at every moment appears in the part near the front zone of the sliding mass (except t=50 s

the maximum speed appears in the front zone of the sliding mass) with three ultimate values of 52 m/s at 14th second

55 m/s at 27 th second

and 49 m/s at 50 th second

respectively. (2) The maximum velocity of the airblast appears at the 50th second with its value reaching 38 m/s. The maximum pressure of the airblast

657 Pa

is generated at the moment the sliding mass bursts out the scarp

which is equivalent to the violent storm. The squeezing effect of the sliding mass on the air ahead is the most obvious when the sliding mass is moving fast and the leading height is higher. (3) The topography along the sliding path displays a large influence on the distribution of airblast pressure. During the high-speed motion of the sliding mass

an obvious gradient variation of air pressure is induced when an obstruction appears along its sliding path

resulting in a destructive effect. When the sliding mass rushes down a scarp or ridge

the velocity of sliding mass will increase rapidly with a negative pressure generated inside of the sliding mass because of weightlessness

meanwhile

a sharply increase of the air pressure will also appear at some locations distributed ahead of the sliding mass due to the intensive compression induced by the sliding mass.