在加勁擋土結構物的內部穩定設計上，加勁材的張力強度與張力分佈為主要的關鍵。現今有許多方式可以用來評估加勁材受力後的張力分佈情況，主要可區分為以力平衡（如側向土壓法、極限平衡法)與以變形（如K 勁度法、有限元素法）為考量的評估方法。但至目前為止，各評估方法的綜合分析與比較之相關研究相當不足。有鑑於此，本文選用兩個同為3.6 公尺但牆面勁度不同之加勁擋土結構物，分別為柔性回包式牆面及剛性混凝土塊牆面，利用實測資料與各項評估方法的預估值進行比較，探討其準確性及可能造成誤差的原因。研究結果發現，K 勁度法在結構物加載後，明顯低估加勁材張力值；有限元素法能準確預測加勁材實際的張力發展；此外，剛性牆面能抵制結構物的側向變形，導致剛性牆面加勁擋土結構物其加勁材張力發展比柔性牆面來的小。然而，以力平衡為考量的預測方法並未考慮牆面的影響，因此普遍呈現高估的趨勢。

Proper estimation of reinforcement loads is a key to evaluate the internal stabilities of Geosynthetic-Reinforced Soil (GRS) structures. Prediction methods for reinforcement loads within GRS structures in current practice can be categorized into two approaches: force equilibrium approach (i.e., earth pressure method and limit equilibrium method) and deformation based approach (i.e., K-stiffness method and finite element method). Until today, the effects of these methods have not been extensively examined and compared yet. In this paper, the reinforcement loads measured from two full-scale and carefully instrumented GRS walls are used to examine the prediction of reinforcement loads by the aforementioned methods. These walls are 3.6m high with different facing stiffness; one wall was constructed with a stiffer segmental modular block face and the other with a flexible wrapped-around face. Comparison results from both wall cases indicate the force equilibrium approach overly predict the reinforcement loads. The K-stiffness method shows an obvious underestimate under surcharging conditions. The finite element predictions are sufficiently accurate under working stress conditions but do not successfully predict the measured reinforcement loads under large loading conditions. Furthermore, a stiff facing in a reinforced soil wall can restrain wall deformation and thus result in significant reductions in reinforcement loads compared to the flexible facing system. However, the influence of facing stiffness is typically not accounted for in the force equilibrium approach, so that the force equilibrium approach significantly overestimates reinforcement loads for the stiff face wall. Reasons of discrepancy between predicted reinforcement loads and measured data are discussed. The results obtained from this study provide insightful information for the design of GRS structures.

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