[[alternative]]Application of Fractal Theory on the Bio-Mechanical Behavior of Rooted Soil

計畫編號：NSC96-2628-E032-037-MY3研究期間：200908~201007研究經費：595,000[[abstract]]在以生態植物護坡功能中之根系補強作用主要源自根的機械補強力量、以及 根對土壤的網結緊縛力量的結果。在一些現地植物根系試驗研究結果，都直接確 認植物根系對土壤有根繫加勁效果，可防止邊坡的沖蝕或淺層崩坍。 然而，根系型態分佈(例如根徑、根長、分佈方向與根密度等)極為錯綜複雜 且是有生命的，根系網絡的發展隨成長期齡而會漸次改變，對土堤或河岸的根繫 穩定效益，也隨時間逐步在改變，並不易以一簡化數學型態代表之。碎形理論適 係用以描述看似雜亂無章、但卻具有規則性或重複繁衍性的幾何物件。自1989 年日本學者Tatsumi等人成功地將碎形維度應用於植物複雜根系的描述後，碎形 理論遂為國際植生生態工程研究中重要的利器之一。 本申請單位歷經一年嘗試性研究後，認為以碎形維度之變化確可能反應植株 成長根系演變幾何特性描述，將會有利建立根系生長與土壤植生根繫力學效益之 關連，因此提出此一計畫。本研究擬分三期進行：(A)現地觀察與挖掘採樣記錄 高矮芒草(不同年齡)之根系成長髮展行為，輔助利用碎形維度量化評估芒草成長 根系網絡之演變[第1年]。(B)進行不同株高芒草根繫土壤強度之試驗研究，包括 根繫土壤土體之室內直剪試驗分析[第2年]；及現地手持式袖珍十字片剪現地強 度試驗[第3年]。期結合根系幾何參數與碎形參數，建構芒草成長過程中，根系 幾何特性在空間的演變與根繫土壤強度增減之關係性。以瞭解植生護坡之穩定效 益，俾利國內對本土性植生根力效益有進一步理解。 The presence of vegetation provides ecological benefits and increases the mechanical stability of soil banks by root reinforced effect. To quantify root effect of local grass (Misscanthus Floridulus) in Taiwan, several properties of the root system need to be established. However, the root architecture and root distribution, the spatial and temporal variability of the growing grass are very complex. The fractal theory is capable of describing a complex nature object, such as the distribution of root system. Recently, the fractal theory became widely use in the topics of ecological plant. In this research, the fractal dimension, box dimension, is adopted to describing the developing geometry of root system for different aged grass. Observation of the growing geometry is recorded for root system of Misscanthus Floridulus. The direct shear test in laboratory and filed hand-held vane shear are performed to investigate the root effect in the increasing of soil strength. The aim of this study is to capture the spatial and temporal variability of the growing grass (Misscanthus Floridulus) and its mechanical reinforcement effect by root in soil banks.[[sponsorship]]行政院國家科學委員