Wind throwing and root wedging occur as trees are overthrown by strong winds. Wind pressure on a tree can produce a destabilizing, moment which will cause it to topple over. The uprooting mechanism has not been clarified yet, and a theoretical uprooting model is proposed and the resistance force of root wedging is estimated in this paper.
The uprooting is considered as a phenomenon that a tree with a hemisphere of soil is detached from the ground, generating resistance force due to friction between the root and the ground. Root wedging force depends on tensile strength and pulling resistance of roots.
The pulling down experiment of trees was carried out to prove the proposed uprooting model true. The moment curves versus the rotation angle of the test trees calculated according to the model is verified to be in conformity to the findings of the field experiments.