根系生長型態與錨碇特性之探討

Study on growth patterns and anchorage characteristics for roots

許雅涵(Ya-Han Hsu)

指導教授 ： 王泰典

國立臺北科技大學/工程學院/資源工程研究所/碩士(2009年)

摘要

植生工法為生態工程邊坡保護措施最重要的方法，用於替代理論背景成熟且應用廣泛的各種鋼筋混凝土結構工法。儘管植生對邊坡穩定的助益在許多報導中已有大量的討論，例如樹葉可攔阻降雨、緩和地表沖蝕，樹木自重可增加邊坡的正向力，樹根可加勁土壤並具錨定作用，可提高邊坡的穩定性等，惟相較於鋼筋混凝土護坡工法具有嚴謹完善的理論背景與分析方法而言，植生工法對於邊坡穩定的效益仍未見系統性的量化分析方法。
本文透過根系的碎形分析、根系生長數值模擬與樹根數值力學模擬，探討根系分佈特性在不同受力條件下的互制行為，以利提供預測植生生長型態與力學關係之依循。研究過程回顧整理植生工法對於土體穩定的相關研究，針對植物根系對土體穩定的評估方法，彙整探討其主要的考量因素，包括植物根系生長形態與分佈探查、植物枝幹生長形態碎形分析、根系力學行為之數值模擬、根-土互制行為參數分析等。運用地電阻與透地雷達尚無法有效探求樹木地底下的根系分佈，而轉換利用碎形理論去尋找樹木枝幹的生長規則性，運用樹枝碎形關係的自相仿性，找出樹木根系生長分佈的規則，而後利用數值軟體模擬根系受力後的力學行為。分析結果顯示，各種形態的根受力越大位移量越大，經由探討根-土變形特性、根-土接觸特性與根系生長形態得知，土壤楊氏模數值越大、根受拉力後位移量越小；根受拉力後由側壁提供主要摩擦力且根的側根越多提供土壤穩定性越大。

關鍵字

生態工程 ； 植生工法 ； 數值模擬

並列摘要

Vegetation engineering is one of the most important methods for slope protection in ecological engineering, and used to replace all kind of methods of reinforced concrete structures which have mature theoretical background and widely been used. Although many reports have mentioned the benefit of vegetation to slope stability, such as leaves can prevent rainfall infiltration and decrease erosion surface; the weight of trees can increase the positive force for slope; roots can enhance soil and provide reinforcement anchoring to increase slope stability. However, compared to reinforced concrete slope protection method which has a rigorous and comprehensive analysis of the theoretical background, there is still a lack of systematic method of quantitative analysis in vegetation engineering.
Through the fractal analysis of roots, experimental-and statistical analysis on roots growth, and numerical simulation for anchored effect of roots, we explore the roots distribution characteristics in different conditions in order to provide the forecast pattern of vegetation growth and mechanical the basis of relations. This study process is to review and organize the relevant research of soil stability in vegetation engineering. We focus on the criticism of the impact of roots to soil stability, and explore the main considerations include: exploration of growth patterns and distribution of roots, fractal analysis of plant growth form, the numerical simulation of mechanical behavior of roots, and the interaction analysis of behavior parameters of roots and soil. Resistively imagine profile (RIP) and ground penetrating radar (GPR) can’t be effective to explore the underground roots distribution of trees. We switch to the use of fractal theory to find the rules of the growth of the trees, and then use the numerical simulation software to explore the mechanical behavior of roots system after the force. Analysis of results showed that the roots of various forms by the greater force, the greater the displacement. By exploring the deformation characteristics of roots and soil, contact characteristics of roots and soil, and growth patterns of roots system, we can conclude that the greater values of Young's modulus of soil, the smaller post-displacement of roots after the pulling force. The interfaces between the roots and the soil provided the main friction after the pulling force, and the more lateral roots, the greater stability of soil can be provided.

並列關鍵字

Ecological Engineering,Root ； Numerical Simulation

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