Preprints
https://doi.org/10.5194/egusphere-2022-468
https://doi.org/10.5194/egusphere-2022-468
 
29 Jun 2022
29 Jun 2022
Status: this preprint is open for discussion.

Dynamic response and breakage of trees subject to a landslide-induced air blast: Implications for air blasts risk assessment in mountainous regions

Yu Zhuang1, Aiguo Xing1, Perry Bartelt2, Muhammad Bilal1, and Zhaowei Ding3 Yu Zhuang et al.
  • 1State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China
  • 2WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, 7260 Davos Dorf, Switzerland
  • 3State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, 610059, China

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 tree base. Large tree deformation 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 the cases with a low air blast velocity, while the large tree deformation 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 of 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 make people better understand the air blast power and be of great utility for air blast risk assessment in mountainous regions worldwide.

Yu Zhuang et al.

Status: open (until 20 Aug 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-468', Anonymous Referee #1, 21 Jul 2022 reply

Yu Zhuang et al.

Yu Zhuang et al.

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Short summary
Trees destruction is often used to back-calculate the air blast impact region and estimate the air blast power. Here we established a novel model to assess the air blast power using the tree destruction information. We find that the dynamic magnification effect makes the trees easier to be damaged by a landslide-induced air blast, but the large tree deformation would weaken the effect. Bending and overturning are two likely failure modes, which depend heavily on the properties of trees.