擋土牆之最佳化設計研究已進行多年，然而一般實務擋土牆最佳化設計僅考慮擋土牆之幾何性質、穩定性、配筋情形為束制條件。但實際上位移因子為擋土牆耐震設計之重要參數，故需將此因子納入最佳化分析之束制條件中，故本研究將位移分析方法納入懸臂式擋土牆之耐震最佳化設計。由於前人研究提出許多基於Newmark 滑動塊體理論之簡化模型來求取地震引致之永久位移，本研究使用30個歷史地震記錄輸入至Newmark 滑動塊體理論及其簡化模型求取永久位移，並統計各模型計算之優劣，來決定一個較佳的永久位移計算模型供最佳化分析使用。 本研究使用實數編碼遺傳演算法搜尋最佳解，本研究額外引入之束制條件為台灣設計規範與擋土牆容許位移為擋土牆高之1/200。最佳化分析結束後，懸臂擋土牆之配筋圖、土方開挖量、回填土方、混凝土方、鋼筋數量皆可自動輸出結果。接續則進行案例測試以確認演算法之效率與可行性，分析結果可顯示不同歷史地震記錄對鋼筋量及工程金額之影響情形。本研究之最佳解發生於案例條件為懸臂式擋土牆設置剪力榫，且搜尋範圍區間為0.01。從案例分析可得知，本研究所提出基於遺傳演算法結合受震位移分析方法之懸臂式擋土牆最佳化設計分析，除了可達到節省工程經費外，亦可使該設計具備安全穩定性與耐震性。 ;Design optimization of retaining wall has been the subject of research for many years. However, the commonly applied design constraints are only geometry, stability and reinforcement. Since displacement is one of the important parameters in seismic design of retaining wall, this parameter should be considered as an additional design constraints. In this study, the displacement-based approach is utilized in seismic design optimization of cantilever retaining wall. A special feature to calculate seismic permanent displacement is installed. Some simplified models used to obtain earthquake-induced displacements based on Newmark’s sliding block theory published by previous researchers have been assessed to determine the proper method and simplify the optimization problem. For this purpose, an appropriate statistical test has been performed to compare permanent displacement obtained from the Newmark’s sliding block analysis and the simplified methods proposed by previous researchers using 30 historical earthquake records. The real-coded genetic algorithm (RGA) is proposed for searching the optimal solution. The constrained conditions involve design codes of Taiwan and allowable displacement of retaining wall 1/200 of height. The design drawing of bar arrangement; the quantities of soil excavation, backfill and concrete, and the number of steels would automatically output after finishing the optimal analysis. Subsequently, some case studies are conducted to verify the efficiency and validity of the algorithm. The results are presented on the effect of different historical earthquake records on the amount of reinforcement and value of cost design. The best optimum solution is obtained for case study using searching increment 0.01 and with shear key. Through some case studies, the proposed RGA and displacement-based design approach demonstrated that they are capable of generating low-cost cantilever retaining wall designs that satisfy safety, stability, and seismic performance of structures designed for earthquake-prone region.
