自火力燃煤發電所產生的剩餘灰燼稱作煤灰，主要分為粗顆粒的底灰與細顆粒的飛灰，目前煤灰處理主要是利用水力排放到海邊築堤的灰塘區，堆置形成煤灰地盤。由於城市不斷的開發，基於用地問題，發電廠已有在煤灰地盤上構築重型儲煤區或擴廠的規劃，但對於此煤灰造地地盤之工程性質研究卻非常缺乏。因此本研究針對煤灰進行一系列的室內試驗，包含基本物理性質試驗、力學性質試驗以及動力三軸試驗，以求取煤灰的各種物理指數與工程性質。由實驗結果得知煤灰依統一土壤分類法，底灰可分類為SW-SM，飛灰為ML，煤灰比重大約在2.29~2.37之間，比一般砂土小，孔隙比較一般土壤大，滲透性良好。由壓密試驗結果得知，煤灰在極短時間內即完成主壓密，與一般土壤差異極大，其中飛灰具有較大的壓縮性。由直接剪力試驗結果得知，純底灰之摩擦角較純飛灰大。由動力三軸試驗結果得知，試體相對密度越大，其液化強度也越大；在相同相對密度下，液化強度大小順序為偏底灰>偏飛灰>純底灰>純飛灰。綜合以上試驗結果，可供未來煤灰地盤進行工程設計時的參考。 The coal ash is a surplus of thermal power which can be separated into fly ash and bottom ash. The coal ash deposit was formed by hydraulic filling is a new geological composition at seaside. In this study, undisturbed samples and remolded samples is used to conduct a series of laboratory physical, chemical, mechanical and cyclic triaxial tests were conducted to obtain the basic, mechanical and dynamic properties of the coal ash. It was found that coal ash is a high void ratio, low specific gravity, non-plastic and cohesionless soil. The fly ash is hollow spherical shaped soil and the bottom ash is irregular granular soil. The cyclic triaxial test shows the behavior of coal ash in a cyclic motion that liquefaction and 5% double axial strain almost happen simultaneous in coal ash samples. At first the coal ash samples had a small deformation and then the deformation will rapid increase after liquefaction happened. The influences of cyclic motion on different coal ash samples were also presented. These test results may provide a valuable base for building designs and considerations in a foundation soil with coal soil.
