加勁擋土牆(Geosynthetic-Reinforced Soil structures)近三十年來在土木工程界發展迅速。現今加勁擋土結構物之設計主要以定量分析(deterministic approach)的方式評估結構物內外部穩定性之安全係數。然而，以安全係數為主的設計方式並未能通盤考慮到設計參數的變異性以及加勁材張力預測公式的模式不確定性。有鑑於此，本文希望能藉由機率方式(probabilistic approach)進行加勁擋土牆內部穩定之可靠度設計，並分別使用三種加勁材張力預測公式(Rankine與Coulomb側向土壓法與K-stiffness法)進行模式不確定性之探討。預期不同預測方法間得到之張力發展值，在考慮模式因子影響後能更加接近實測結果。本研究首先蒐集加勁擋土牆參數與加勁材張力發展的實測資料，根據實測值與預測結果量化模式不確定性。之後，以參數靈敏度分析結果，找出影響加勁擋土牆內部穩定性較大(如破壞機率變化較大)的參數為可靠度分析時需考慮的變數，並進一步進行可靠度分析，發展出一系列可靠度設計圖。最後，本論文舉一案例說明可靠度設計圖考慮模式因子影響之設計變化。本研究發現在未考慮模式不確定性之情況下，加勁材斷裂模式中，相同破壞機率下的側向土壓法計算之張力發展值遠大於使用K-stiffness法所計算之結果。而在考慮模式不確定後，相同破壞機率下的側向土壓法所計算之張力發展值與K-stiffness法計算結果變得接近。

Over the past three decades, Geosynthetic-Reinforced Soil (GRS) structures have been developed rapidly in civil engineering related construction. Nowadays, GRS structures are conventionally designed using the deterministic approach to calculate the factors of safety against internal and external stabilities of GRS structures. However, the deterministic approach is not able to consider variability and uncertainty from design variables and prediction models. In contrast with the deterministic approach, the reliability approach considering the possible variations in the design parameters and the model uncertainty of design methods for predicting reinforcement loads (i.e, earth pressure methods using Rankine’s and Coulomb’s Ka and K-stiffness method) can estimate the safety of the structure and the possible risk of failure more realistically. In this study, the model uncertainty is statistically quantified using a model factor, defined as the measured reinforcement load divided by the predicted reinforcement load. The model factor is simulated using two approaches: generalized model factor and correlation model factor. A series of RBD design charts with and without incorporating model uncertainty is developed. The RBD results are compared and the impact of model factor on the prediction of reinforcement tensile loads is investigated. It is expected the RBD results using three prediction methods become more consistent when the model uncertainty is considered. The results obtained from this study provide insightful information of RBD for internal stability of GRS structures.

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