實驗結果顯示層狀加勁砂柱能有效提升軟弱黏土中砂柱的承載能力，當加勁材降伏前其張力勁度越大則能提供砂柱更大的承載能力，加勁材強度越大則使最終承載能力越好，設置加勁材也使上方載重傳遞更大應力至砂柱底部。安裝加勁材能提升砂柱整體勁度及抑制腫脹，但也讓上方力量向砂柱底部傳遞，使砂柱腫脹範圍向下延伸。層數配置部分，五層加勁砂柱除提供較少加勁效果外，加勁材層與層之間有較大的間距使加勁材的圍束效果不明顯，對頂部砂柱腫脹的抑制效果較少。十層加勁砂柱因有較密的間距能使加勁材提供的加勁範圍較大，使砂柱腫脹較小且平均於整體砂柱。延展性較差之地工合成材易於低應變下產生破壞，提供砂柱承載能力與抑制砂柱腫脹情況有限，使用多層加勁材仍無明顯增量。 Sand columns have been used in engineering practice to improve the bearing capacity of soft clay in recent years. Although the sand column can bear axial stress and shear stress from surface load, but due to the lack of lateral confining pressure in the near-surface that often caused bulging failure in the top portion of the column, reduce the carrying capacity of the sand column. Reinforce a sand column with laminated geosynthetics is feasible and effective solution to improve bearing capability of a sand column. In this study, model test on single geosynthetic-laminated sand columns installed in soft clay was conducted. Similarity analysis was executed first to determine suitable properties of the constituents used in the model tests to ensure comparable behavior between the prototype-scale and model-scale reinforced granular columns. Three types of geosynthetics was employed to reinforce the sand columns either with 5 or 10 layers of geosynthetic sheets horizontally placed in these model sand columns. Experimental results showed that horizontally inserted reinforcements improve the bearing capability of the model sand columns; marked improvement was achieved for sand columns reinforced with geotextile of relatively medium to high stiffness. Horizontal reinforcement also restrained radial strain of the columns significantly. Additionally, horizontal reinforcements affected stress transmission character along the length of the sand column and thus the bearing capability of the column.
