Preliminary Study On Non-destructive Method And Safety Assessment Of Tree

In resent years, garden department and arboriculture are pay attention to Tree’s Non-destructive evaluation and safety assessment. Non-destructive evaluation means be determined without injury, it is utilize materials different physics mechanics and chemistry characteristic, based on not breakage the inner and appearance configuration, test the correlation characteristic, such as:the shape, the displacement, the stress, the photics characteristic, the Liquid characteristic and the mechanics etc, Especially the different defects. The most prominent characteristics of Non-destructive evaluation is not breakage the primary characteristic of material, and obtain the result continuous in short time. Standing trees safety means there are holes or decay themselves, or occur breakage of root, the possibility of occur breakage by other external factors. According to the study in recent years, it was found that there are a lot of literatures about this in abroad, and forms a comparatively perfect system. Some garden-departments can’t completely reference other countries standard while manage Landscape Trees, ancient and famous trees. It is the basic aim of this paper, study based on Non-destructive evaluation and forms a tree safety assessment model. Finally forms a comparatively perfect tree safety assessment system, the result could as a reference for related departments engage in trees maintenance.There are three parts of this paper; the first part is study of Non-destructive evaluation. The cedar sample, phoenix tree, ancient and famous trees of Scenic Area in the Huangshan Mountain were tested by the technique of stress wave and resistograph, include the theory of the two Non-destructive methods analysis, stress wave tomography analysis which come from the tree with hole or the healthy trees. Study based on stress wave and resistograph for determine cedar sample interior characteristic, ancient and famous trees test. The second part is bending test for metasequoia interior characteristic assessment. Study with statical strain indicator system, Based on the results make a correlation of strain-wind simulation, the relation of strain and tree diameter with the same wind, and how to assessment trees interior characteristic. The third part is base on the former two sections, combines with mechanics forms a model, makes sure specific approach method for tree safety assessment, and ultimately forms a comparatively perfect safety assessment system. The results of this research are as follows:1. Used the stress wave can simulate the shape of trunks, and the similarity are well,when the hole of the tree is very large, the stress save tomography can show the hole’s shape and location, and there is a good correlation. 2. The results showed that the photographs which come from stress wave and resistograph could exhibit the distribution of cedar sample interior characteristic, stress wave was combined with resistograph to determine standing tree interior characteristic could improve the testing accuracy and make up for the deficiency of both instruments. Moreover, when compared with wood density, both of the correlation coefficients are greater than0.8, It could prove that there is a good correlation between the information of photographs which come from stress wave and resistograph and the wood density.3. Field detection of ancient and famous trees based on stress wave. The results showed that,stress wave tomography can determine ancient and famous trees interior characteristic, stress wave can used as a assistant tool while ancient and famous trees management.4. The bending test could obtaine tree’s strain regularity under simulation wind. Based on the fitting equation, it can obtaine the strain of the same diameter in wind.5. There is a good correlation between the diameter-strain, all of the correlation coefficients are greater than0.98, the strain’s fitting equation of different diameter metasequoia under2000N simulation wind is:y=25726e-0.0161x.6. The relation of E and resistance of different diameter trees are not well, the correlation coefficient is0.75, so the resistance individual can’t use to assessment standing tree interior characteristic.7. The E of the tree’s trunk come from bending test are about7GPa, it was near the real E of the tree’s trunk, except the number1is likely to exist decay or hole in the trunk,because the resistance determine show a lower resistance compare with other trunk., other trees not exhibit a obvious defect, the interior characteristic are well, The results show that bending test can use to assessment standing tree interior characteristic.8. While assessment the safety of the standing tree, loss of strength is the key, use Wagener, coder, Mattheck and Fraedrich equation combine with stress wave tomography can assessment the loss of strength of the standing tree. Based on wind power and the strength of bending formula, can obtain the limit strength of bending in nature, with the result can assessment the safety of the standing tree.