火力電廠發電後的產物即為煤灰，煤灰目前主要的處理方式是在海邊建造灰塘，將煤灰以水力回填的方式填海造地，回填後的煤灰地盤上可擴建發電機組、大型煤倉或風力發電機，此類大型建設多採用樁基礎，所以煤灰地盤樁基礎之承載行為則顯得重要。故本研究針對台中火力電廠之煤灰進行一系列之大地工程試驗，其中包含基本物理性質試驗與力學性質試驗，試驗結果顯示，煤灰依統一土壤分類法，底灰可分類為SW-SM，飛灰為ML，煤灰比重大約在2.29~2.37之間，煤灰在極短時間內即完成主壓密，與一般土壤差異極大，其中飛灰具有較大的壓縮性。並於台中火力電廠灰塘與林口火力電廠灰塘進行現地樁載重試驗，試樁t-z與q-z曲線結果發現，改良效果在應變軟化之土層較為明顯，而在應變硬化行為之煤灰土層改良效果不明顯。 本研究設計一套可進行單向或雙向之反覆模型樁載重試驗，其作用週數可達一萬循環以上，且其作用頻率最高可達0.1Hz，並進行雙向垂直反覆樁載重試驗，探討煤灰地盤受反覆垂直荷載後，樁頭等效勁度、樁身軸力與累積殘餘位移隨作用週數之之變化。試驗結果發現，小的反覆載重振幅"1" /"12" "P" _"u" 作用下，在高循環作用後，樁頭累積殘餘位移會逐漸穩定不再明顯增加，而反覆載重振幅在"1" /"6" "P" _"u" 與"1" /"3" "P" _"u" 時分別於500與20循環之後，有較大的累積殘餘位移。反覆加載形式會影響樁頭累積殘餘位移，先解壓再加壓之樁頭累積殘餘位移會大於先加壓再解壓。由試驗資料可得反覆等效勁度比與作用週數之關係式，利用此關係式可預測不同反覆載重振幅作用下，不同之作用週數下基樁之累積殘餘位移。殘餘樁身軸力均不會隨著反覆作用之振幅大小所影響，也不會隨著作用週數變化。樁底部之軸力則隨著作用週數增加而增加，可見作用週數之多寡為控制樁底累積殘餘軸力之主要因素，但卻不會影響樁身之累積殘餘軸力。 ;Coal is the most common material used in thermal power plant, and coal ash is the end product after the power generation. The main treatment of coal ash is to hydraulically transport to the ash pound which was built near the power plant, then it become a newly reclaimed land. The new power generator, coal bunker, and wind turbines can be built on this newly land because these facilities always use pile as its foundations. Therefore the pile loading behavior in ash pound is very important for engineer to study. In this study, undisturbed samples and remolded samples are used to conduct a series of laboratories including physical, chemical, and mechanical tests to study the geotechnical properties of coal ash. The test results show that specific gravity of coal ash is 2.29 to 2.37, and complete the primary consolidation in very short time. The filed axial pile load test results in coal ash pound built in Taichung and Linkou thermal power plant show that the effect of improvement is more significant in strain softerning zone. This study designs a model pile test which can provide one way and two way cyclic loading which the highest frequency is up to 0.1Hz and at least 10000 cycles. By using this test equipment, this reserch study the relationship of pile head stiffness, axial load on pile, pile head displacement, and the load cycles. The test results show that the pile displacement will not increase at the small cyclic amplitude after high cycles. The loading type will effect the pile displacement. The cyclic amplitude and number of cycles will not effet resudial load along the pile, and the nuber of cycles will effect the resudial end bearing load of the pile.
