根力模式與含根土壤剪力強度增量之研究

The Study of the Root Strength Models and the Shear Strength Increment on the Soil-Root System

游新旺(Hsin-Wan Yu) ； 陳主惠(Chu-Hui Chen) ； 吳瑞賢(Ray-Shyan Wu) ； 陳秀婷(Hsiu-Ting Chen)

《農業工程學報》 54卷4期 (2008/12) Pp. 83-97

https://doi.org/10.29974/JTAE.200812.0006

摘要

根力模式將土壤之剪力強度增量視爲根在力學上之加勁行爲，根之埋置長度與剪力帶厚度變化將影響含根土壤之剪力強度。本研究依據大麥及松樹根之彈性變形、斷裂現象及根與土壤間握裏滑移作用等力學行爲，建立含根土壤之根力模式，探討根系對土壤剪力強度增量之影響。研究中發現，考慮實際錨錠機制所增加之根理置長度，在土－根握裏強度低時，可提高含根土壤之剪力強度增量及其位移－抗剪應力增量關係之初期勁度，但在握裏強度高時，根之埋置長度增加，對含根土壤之剪力強度增量貢獻不大。另對於剪力帶厚度之研究，本研究模擬剪力帶厚度與土壤側向位移關係分別爲常數、線性及二次曲線，探討剪力帶厚度變化對土壤剪力強度增量之影響，分析結果顯示，合理的剪力帶發展機制模擬，確可改善剪力帶厚度爲定值之缺點。

關鍵字

根力模式 ； 剪力強度 ； 剪力帶 ； 錨錠

並列摘要

The shear strength increment of the soil is taken as the reinforcement on root mechanism in the root-strength models, and different root embedment lengths and shear zone thicknesses may influence the shear strength of rooted soil, An analytical model responds to the loading of root stretching, root breaking, and soil-root slipping is established in this study to discuss how the root systems influence the increment of the shear strength of the pine and barley rooted soil. It is found that the larger root embedment length according to actual anchoring mechanism did improve the soil shear strength increment and the initial stiffness in the displacement-shear stress increment curves at the low bond strength of root, but has a slight effect on the shear strength increment by increasing the root embedment length at the high bond strength of root. We also simulated the shear zone thickness versus lateral displacement with different approaches in constant, linear, and quadratic relation as the shear stress progresses to investigate the relation between the thickness of the shear zone and the corresponding shear strength increment of the soil. The results showed that with reasonable simulation for the shear zone development mechanism is able to improve the defects on assuming constant shear zone thickness.

並列關鍵字

Root strength model ； Shear strength ； Shear zone ； Anchored