現場含根土壤直接剪力試驗與抗剪強度增量評估

本研究對現場實施整地、挖土至土體製作，再進行土體的直接剪力試驗，並繪製不同土體的剪變位與剪力強度關係圖。直接剪力試驗完成後，於剪斷面處讀取根數且在試體周圍取出相當數量之植物根作根徑－長度量測與直接拉力試驗，以取得現場植物根的必要參數，並據以進行根力模式分析。由於現場植物生長在排水情況不佳和土質不一致情況下，土壤的根系顯得錯綜複雜，造成根力模式不容易評估含根土壤之剪力強度增量。故本研究於模式分析時，考慮剪力帶厚度和土根間之平均握裹強度為變量，分別尋求含根土壤抗剪強度增量值。經由分析結果與現場試驗結果比較發現，隨著土體側向位移量的增加，剪力帶厚度將增加，但土根間之平均握裹強度則隨土體側向位移量的增加而有變小的趨勢。

關鍵字

含根土壤；現場直接剪力試驗；剪力強度

並列摘要

This study performed the field direct shear tests on soil samples after on-site soil preparation, digging, and production. The direct shear tests were proceeded and the relationship between the shear strength and the lateral displacement was established simultaneously. After the test, the number of roots on the shear plane was counted and then the plant roots around the samples were extracted to measure the roots diameter and length and conduct direct tensile tests. According to the data obtained from experiments, the statistical analysis was performed to obtain the parameters for the root strength model study. Because the field plants exist in the poor-drained sandy and non-uniform grained soils, the roots of the plants on the field soils appear to be more complicated. It is not easy to evaluate, the shear strength increment of the soil using the model analysis with simple assumptions. Hence, this study used shear zone thickness and average root-soil bond strength as variables to explore the influences of these variables on the shear strength increment of rooted soils. By comparing with the result of the model analysis and the on-site test, it was found that, as the lateral displacement of the soil increased, the shear zone thickness increased and the average root-soil bond strength decreased.

並列關鍵字

Rooted soil ； The field direct shear test ； Shear strength

國際替代計量

現場含根土壤直接剪力試驗與抗剪強度增量評估

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