| 摘要: | 在大地工程領域中，邊坡穩定性是長期存在的關鍵課題，而環境友善的加固技術也日益重要。本研究以低水泥含量的飛灰樁（FA-Piles）為研究對象，透過離心模型試驗探討其對邊坡穩定之影響。邊坡模型之材料使用 80% 矽砂與 20% 高嶺土混合而成，其分類為 SC ，凝聚力和摩擦角分別為10.53 kPa 及 32.73° 。邊坡模型之高度為 200 mm、基底厚度 50 mm，坡度為 70°，在 95% MDD、乾密度 17.9 kN/m³ 及含水量 14.2% 的條件下壓實成型。
本研究綜合評估水泥種類（LCC 與 OPC）、施工方式（預製與灌注）以及樁距（6.7d、5d、4d）等參數，觀察這些參數在靜力條件下對邊坡行為的影響。樁體材料採用 5% 水泥、15% 飛灰與 55% 土壤混合物的低水泥環保砂漿，並進行 28 天養護，用以比較其與傳統高水泥含量配比之可行性。樁體尺寸方面，直徑為 10 mm，長度則為100 mm。
此研究共進行十二組離心模型試驗，其中包含未加固邊坡作為對照組。結果顯示，低水泥含量的飛灰樁可大幅提升邊坡穩定性。未加固邊坡約在 45g 時發生破壞，而在 4d 樁距與OPC 灌注配置下，破壞時加速度可提升至約 80g。樁體使標準化後的變形土體量降低 40–60%，並縮短滑動與堆積之距離，同時提供相當的樁體抗力，樁體總貢獻可達 247 kN，單樁則可提供超過 20–30 kN 的抗力（依配置而異）。整體結果歸納為以下三點：（1）OPC 材料之強度與承載轉換能力較佳，整體表現優於 LCC；（2）灌注法施工能形成更強的土–樁鍵結，穩定效果明顯優於預製法；（3）樁距為影響最大的主導因子，其中 4d 樁距表現最佳，能達到最高的破壞 g 值、樁體抗力以及抑制變形之能力。
綜觀各項分析，低水泥含量的飛灰樁即便膠結材料含量較低，其仍具良好結構效能，是淺層邊坡加固中同時具有環境永續性與工程可行性的替代方案。本研究提供關於膠結特性、施工方式、樁距配置等參數與加固效能之關係，可作為未來永續大地工程設計之參考基礎。
;The stability of slopes is a crucial issue in geotechnical engineering, and the development of environmentally friendly reinforcement methods has become increasingly important. This study investigates slope stabilization using fly ash piles (FA-Piles) with a low cement content through centrifuge modeling. The slope model was constructed from a mixture of 80% silica sand and 20% kaolin clay, classified as SC with a cohesion of 10.53 kPa and a friction angle of 32.73°. The slope height was 200 mm with a 50 mm foundation and an inclination of 70°. It was compacted to 95% MDD with a density of 17.9 kN/m³ and a water content of 14.2%. The research evaluates the combined effects of cement type (LCC and OPC), construction method (precast and injection), and pile spacing (6.7d, 5d, and 4d) on slope behaviour under static conditions. A mortar composition consisting of 5% cement, 15% fly ash, 25% water and 55% soil mixture was used to assess the feasibility of sustainable, low-carbon reinforcement materials in comparison to conventional higher-cement mixtures, with a 28-day curing time. The pile geometry was 10 mm in diameter with 100 mm in length.
Twelve centrifuge tests were carried out, including an unreinforced baseline. The results demonstrate that the low-cement piles significantly enhanced slope stability, increasing the gravitational acceleration at failure from 45g (bare slope) to as high as 80g in the 4d OPC-injection configuration. The piles also reduced the normalized deformed soil volume by up to 40–60%, shortened the collapse and accumulation distances, and mobilized substantial resisting forces, with total pile contributions reaching 247 kN and single-pile contributions exceeding 20–30 kN, depending on the configuration. Key behavioural trends were also identified: (1) OPC mixtures consistently outperformed LCC, reflecting their higher UCS and improved load-transfer capacity; (2) injection installation was superior to precast, providing stronger soil–pile bonding and higher stabilisation efficiency; and (3) pile spacing was the dominant geometric factor, with the 4d configuration producing the highest g-failure accelerations, greatest pile resistance, and most effective deformation confinement. The findings confirm that fly-ash–based low-cement mortar piles remain structurally effective despite their reduced binder content, offering a viable and environmentally responsible alternative for shallow-slope reinforcement. The study provides quantitative insights into the relationships between binder behaviour, construction method, spacing, and stabilisation performance, forming a basis for sustainable design development in geotechnical engineering. |
