經研究結果顯示：(1) 土壤未達到液化狀態時，其加速度振幅會隨土層深度越淺而有所放大，且小振動具有較高的放大倍率。土壤液化後由於剪力波無法向上傳遞，因為液化土層中的加速度振幅會呈衰減的趨勢；(2) 經由加速度歷時的對照，液化振動事件時未改良煤灰層之加速度振幅從第一個週期後開始衰減。砂樁改良組的煤灰層保留了前二個週期的完整波型，顯示出經改良煤灰土層之抗液化能力略高於未改良煤灰土層；(3) 綜合加速度與超額孔隙水壓比歷時，未改良煤灰層之液化深度達到8.5m，且超額孔隙水壓激發後所需的消散時間極長。而經過砂樁改良的煤灰層之液化深度同樣達到8.5m，但振動結束後水壓便開始迅速消散，顯示設置砂樁有利於煤灰層的排水。 ;In this research, series of dynamic centrifuge tests were performed to investigate the seismic behavior of liquefiable ash ground with different configuration. The ash samples were collected from the ash pond of thermal power plant in Linkou and made into consolidation samples. Tested models are divided into two groups according to the thickness of ash ground. All the models were installed the accelerometers, pore water pressure transducers and linear variable differential transformers (LVDT) to observe the seismic response of ash ground during and after soil liquefaction.
The test results showed: (1) the acceleration amplified from the base of soil stratum to the top while soil was non-liquefaction. On the other hand, the liquefied soil layer obstructs the shear wave propagation causing the decrease of acceleration. (2) The results of acceleration history showed that ash ground with sand pile improvement have slightly higher liquefaction resistance than unimproved ash ground. (3) The dissipation time of excess pore water pressure of liquefaction ash ground is very long. Instead, the excess pore water pressure of ash ground with sand pile improvement dissipated immediately after shaking.
