Building And Analysis Of Mechanics Model For Windthrow Of Spruce

A major reason of making the gaps is the windthrow that is a factor of ecology turbulence, and it is a common disaster for wood productions, therefore , to study mechanism of windthrow is very important. There are no any investigations about this field in our country now. Windthrow is constant to the forest, involving stem damage and uproot. It is mainly effected by the trees'own attribute , soil bear and the force of wind. Its own attribute have a relation with the tree age , stem strength, stand structure, the shape of the tree crown , the defects in the wood, and so on. The soil resistance is effected by the soil tension, the soil shear, the containing water capacity, the depth, the width and the weight of the tree root. The resistance to wind was determined by both of them. The wind facter contains wind speed , pressure, frequency and the distribution of wind.Mechanical mechanism of the windthrow of scale spruce in the northeast area have been opened out in the study, which combine mechanics with the biology properties in tree. This paper mainly study the windthrow mechanics character of scale spruce in the northeast area. Adopting non-linearity hypothesis, it regard the tree stem as an elastomer and establish three dimension elasticity medium model of the crown and the trunk of a tree to study it. Hold the trunk of a tree as a changed section style to treat with and simulate the bending and distortion produced by the natural wind, finally to open the mechanic mechanism of the windthrow phenomena out.The major contents are as follow in the study. 1. Local observations of the shape on the spruce tree at Northeast Region have been fulilled , researched their shape parameters and token technique and established mechanical model corresponded the shape. 2. The biomechanical properties about structural stiffness and elastic modules have been obtained. 3. The anchorage strength of a root system in soil have been tested, observed and analyzed tree that come into being maximum resistance moment against the part over ground.4. A nonlinear mechanical model have been founded.When the tree was subjected to the deformation, study the value and the distribution of the stress and the yield...