水土保持常用植物山芙蓉、九芎及山黃麻土／根系統之拉拔抗力及剪力強度增量之比較

Comparisons of Pull-Out Resistance and Shear Strength Increment of Soil/Root System for Plants Commonly Used in Soil and Water Conservation: India-charcoal Trema, Cotton Rose, and Subcostate Crape Myrtle

林德貴(Der-Guay Lin) ； 王勝賢(Sheng-Hsien Wang) ； 陳威翔(Wei-Hsiang Chen) ； 鄒瑞卿(Jui-Ching Chou)

《中華水土保持學報》 47卷2期 (2016/06) Pp. 84-94

https://doi.org/10.29417/JCSWC.201606_47(2).0004

摘要

根系對於土／根系統剪力強度產生之增量，可以採用凝聚力之增量來表示，本文研究三種坡地水土保持常用植物之根系型態，對土／根系統拉拔抗力及剪力強度增量之影響。依據三種植株之土／根系統之數值模型，可進行其抗拉拔與直剪兩種試驗之數值模擬。分析結果顯示，土／根系統極限拉拔抗力P_(max)之模擬值與量測值相當吻合。同時，三種植物由於根系所獲得之土壤剪力強度增量ΔS_r，隨根系型態不同而有所差異，且其值皆隨著根系基徑D之增大而增加。ΔS_r值隨著D值呈正比增加，其增加率之大小排序為：九芎＞山芙蓉＞山黃麻。

關鍵字

土／根系統 ； 數值模擬 ； 拉拔抗力 ； 剪力強度增量

並列摘要

This study investigates the influences of root morphology on the pull-out resistance and shear strength increment of soil-root system for three species of plants commonly used in the soil and water conservation of slope land. The increment of shear strength of soil/root system due to roots can be expressed in terms of increment of cohesion of soil mass. According to the numerical models of soil-root systems of the three plants, one can carry out a series of numerical simulations of pull-out and direct shear tests. The analyses indicate the simulations of ultimate pull-out resistance P_(max) of soil-root system are in good agreement with measurements. Meanwhile, the shear strength increments ΔS_r due to roots of the three plants are different and vary with their specific root morphology. The ΔS_r values increase proportionally as the basal diameter increases, in the order: (Subcostate crape myrtle) ＞ (Cotton rose) ＞ (India-charcoal trema).

並列關鍵字

Soil/root system ； numerical simulation ； pull-out resistance ； shear strength increment