地震引致的土壤液化會對建築物造成損害、進而威脅人民和身家財產。大多數的對策是提出減少積聚在土壤內超額孔隙水壓力，以加強地震來時土壤對抗液化的能力。垂直排水系統是公認有效的方法，透過使用高滲透性的材料、提供水壓能於較短且迅速的消散路徑。在這項研究中，目的是利用離心模型試驗來證明垂直排水系統對抗土壤液化的效果。而離心模型試驗內容包括使用地工合成排水帶，垂直排水砂樁於來改良液化土層。並利用加速度計及孔隙水壓計和LVDT等感測器，來量測土層間剪力波速的傳遞，自然頻率，孔隙水壓力變化的趨勢和地表位移（水平和垂直），並利用合適的軟體描述，令物理數據變化更加明顯。根據測試結果，垂直排水系統能夠顯著減少在地震作用下超孔隙水壓力的上升，並提供快速通過的水流通道，有效減少地表沉陷和建築物的傾斜與變形。 關鍵詞：離心模型試驗研究，土壤液化，垂直排水系統。 ;It was observed that liquefaction induced by earthquake causes series damages to buildings and threatens the people and their properties. A majority of countermeasures were proposed to reduce the build-up of excess pore water pressure and to enhance the stiffness of the soil during earthquake against soil liquefaction. The vertical drain systems are well known methods which is to provide rapidly shorter dissipation path of water by the use of higher permeability material playing role as vertical drain and it can be installed through the liquefiable soil layers against earthquake-induced soil liquefaction. In this study, the purpose is to clarify the effect of vertical drain methods on the soil liquefaction by high quality centrifuge modeling. Several centrifuge modelling experiments were performed including geosynthetic belt drains and pile sand drains as vertical drains in improved model. By the use of centrifuge data supported, two arrays of accelerometers, the pore water pressure transducers and several displacement transducers were assembled to examine the shear wave propagation, predominant frequency, pore water pressure tendency and ground displacement (on horizontal and vertical plane) and utilize suitable software to describe the physical data meaning become more obvious. According to the test results, it was observed that the vertical drain systems could reduce the excess pore water pressure ratio significantly under seismic loading and fasten dissipation process by providing rapidly water flow path, thereupon seemingly leading curtail surface settlement of soil and angular distortion of building thank to lower excess pore water pressure. Keywords: Centrifuge modelling, soil liquefaction, vertical drain systems.
