耐風特性を考慮した斜面上緑化樹木の安定性に関する研究

在大面积的开发中，需要用复原树来代替早期恢复自然环境。但风害对本工程坡面立地的影响并不明确。本研究以树根、树干、树枝、树冠为研究对象，分析了树体抗风结构的总体机理，构建了基于连根折枝模型的树体重建设计方法。分析所需的基础数据是根系的强度、林分的杨氏模数、林分和树枝的振动特性。首先，从树桩阻力矩的过程考虑林分下部张拉力拔除试验结果。并建立了在此力作用下拔除的阻力矩模型。此外，在没有获得树桩根系的情况下，建立了简化模型。其次，对8种阔叶树种和针叶树种进行了根系拉伸试验。断裂载荷随断裂部位直径的2次方变化。根的强度为茎的木质部。第三，对过去的拔根试验结果进行了排列。结果表明，拔除的最大阻力矩与林分胸径的3次方成正比。第四，测定了林分杨氏模数，柳杉的杨氏模数约为80tf/m~2，钝顶柳杉的杨氏模数约为100tf/m~2。主振周期为0.66赫兹，与本例的风压周期相同。

The revegitation tree is required in place of to early restore the natural environment in the development of large area. But the influence of wind damage does not make clear for the stand on slope in this project. The object of this study analysis the total mechanism of sturcture with wind resistance for tree which consists of roots, stem, branches, and crown, and construct the method used in design of revegetation tree based on the model of uprooting and stem breakage. Fundamental data required this analysis is strength of roots, Young's modulus of stands, characteristics of vibration of stands and branches.The results for 3 years studying summarize as following. First, Results of uprooting test by applying tensile force to lower point of stands were considered from the process of the resistance moment for tree stump. And the model of resistance moment was constructed for uprooting in the case of this force acting to stand. Furthermore, simplified model was made in case of no obtaining the root system of tree stump. Second, the tensile test of roots was made for 8 species of hardwood and conifer. The rupture load varied as the second power of the diameter in the part of rupture. And root strength was as the xylem of stem. Third, The results of past uprooting test were arranded. And it was made clear that the maximum resistance moment of uprooting was proporting to the third power of the breast diameter of stand. Forth, Young's modulus of stand was measured, the value of cryptomeria japonica was about 80tf/m^2, and the value of chamecyparis obtusa was about 100tf/m^2. The variation of tree by high wind was measured. The main period of vibration was 0.66Hz as same as periods of wind pressure in this case.