大部分的火力發電廠是以燃煤產生熱能發電的。燃煤除了發電外，也產生煤灰，但基於環保要求，煤灰不得運送至廠外處理，故以水力回填的方式將煤灰運送至鄰近發電廠的海邊進行回填，便形成了煤灰地盤。大型火力發電廠利用鄰近回填的煤灰地盤進行擴建。但是台灣地震頻繁，對於細料含量高的無塑性煤灰來說，是相當容易發生液化的。因此為了擴建的需要，台中及林口的火力發電廠分別進行了擠壓砂樁以及排水礫石樁來改良煤灰地盤。但對於淺層煤灰之擠壓效果不佳，也無法觀察確認其排水效果，因此需要針對煤灰地盤進行模型試驗。 為瞭解改良後的煤灰地盤在地震作用下的液化潛能，本研究以離心試驗模擬改良後的煤灰地盤受震反應，並以加速度歷時、水壓歷時、沉陷量來瞭解受震後的煤灰液化特性液以及改良工法對煤灰地盤的排水效果。根據試驗結果所得結論為:(1)不論是排水砂樁或是排水礫石樁，樁距2.5公尺與3公尺之改良效果無明顯差距；(2)煤灰液化時，顆粒容易被帶進礫石樁內，導致礫石樁排水效果不佳；(3)包覆濾層能有效防止煤灰顆粒滲入礫石樁內，且能減輕淺層煤灰地盤液化的情形。 ;For many Fossil-fuel power stations, burning coal is the most used type to generate electricity because coal is cheaper than other material. Not only generating electricity, but burning coal also produced ash named coal ash. Because of environment demand, it is not allowed to transport ash to overseas. Thus it is used to transporting ash from thermal power plant to adjacent seashore by hydraulic filling and building ash ground. The large thermal power plant used ash ground to expanse plant area, but there are many earthquakes in Taiwan. Liquefaction can easily happened in ash with high fines. Therefore, they conducted sand compaction pile and gravel drain pile to improve ground in Taichung and Linkou. Consequently, the effective of compaction is not obvious for shallow ash ground and difficult to observe the influence of drain, and acknowledge of liquefaction characteristics of ash is insufficient. For these reasons, it is necessary to conduct modeling test. This study presents centrifuge modeling tests designed to simulate the vibration response of improved ash ground. According to test results: (1) It’s no obvious difference between piles space 2.5 m and 3 m, no matter sand drain pile or gravel drain pile. (2) It’s easy for coal ash to be taken into gravel pile when liquefaction, resulting in drain gravel pile is ineffective. (3) It’s effective to keep coal ash away from gravel pile with filter, and to mitigate liquefaction of shallow coal ash ground.
