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Abstract. Landslides have been known to generate powerful air blasts capable of
causing destruction and casualties far beyond the runout of sliding mass.
The extent of tree damage provides valuable information on air blast
intensity and impact region. However, little attention has been paid to the
air blast–tree interaction. In this study, we proposed a framework to assess
the tree destruction caused by powerful air blasts, including the
eigenfrequency prediction method, tree motion equations and the breakage
conditions. The tree is modeled as a flexible beam with variable
cross-sections, and the anchorage stiffness is introduced to describe the
tilt of the tree base. Large tree deflection is regarded when calculating the
air blast loading, and two failure modes (bending and overturning) and the
associated failure criteria are defined. Modeling results indicate that
although the anchorage properties are of importance to the tree
eigenfrequency, tree eigenfrequency is always close to the air blast
frequency, causing a dynamic magnification effect for the tree deformation.
This magnification effect is significant in cases with a low air blast
velocity, while the large tree deflection caused by strong air blast loading
would weaken this effect. Furthermore, failure modes of a specific forest
subject to a powerful air blast depend heavily on the trunk bending strength
and anchorage characteristics. The large variation in biometric and
mechanical properties of trees necessitates the establishment of a regional
database of tree parameters. Our work and the proposed method are expected
to provide a better understanding of air blast power and to be of great use for
air blast risk assessment in mountainous regions worldwide.