砂質水泥改良土剪脹之依時性;Time dependency of dilatancy for cement treated sandy soil

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68014

Title:	砂質水泥改良土剪脹之依時性;Time dependency of dilatancy for cement treated sandy soil
Authors:	蔡秉諺;Tsai,Bing-yan
Contributors:	土木工程學系
Keywords:	三軸壓密不排水試驗;潛變試驗;剪脹係數;時間依存性;CU test;creep test;coefficient of dilatancy;time dependency
Date:	2015-07-28
Issue Date:	2015-09-23 10:12:22 (UTC+8)
Publisher:	國立中央大學
Abstract:	利用水泥來進行土壤改良，透過少量的水泥添加，可提升回填土壤之工作性及適用性。在過去已有相關之動力三軸、靜力三軸及抗分散劑之添加等的研究與成果。然而，在受剪時間效應部分之探討卻仍顯得不足。本研究針對此一部分，進行相關之試驗分析與探討。在靜力三軸壓密不排水試驗方面，結果顯示添加水泥後，砂土產生改良作用，使得剪力強度提升。以靜力三軸壓密不排水潛變試驗，來瞭解水泥改良土之超額孔隙水壓隨時間之變化，試驗結果顯示添加水泥能降低超額孔隙水壓隨時間的增量。將試驗數據繪製成圖形並加以分析，求得一組不同水泥配比的剪脹係數與時間之關係式，經由此關係式可計算砂質水泥改良土受長時間軸向加載之超額孔隙水壓增量。以靜力三軸壓密不排水分階加載試驗來模擬，比較試驗結果與關係式之計算值是否相近，結果兩者十分一致，顯示本研究所得之關係式，具有一定之準確性，可用來作為實務上推估超額孔隙水壓隨時間之增量。最後，進行動力三軸試驗，探討其超額孔隙水壓之變化，結果發現與靜力試驗結果不同，快速加載有產生負值超額孔隙水壓之趨勢。 ;To improve soil properties with cement, we may add a small amount of cement to enhance the workability and suitability of soil. A lot of researches had been conducted with cyclic triaxial tests, CU tests, and adding different types of coagulant in the past. However, research about time dependency of dilatancy is rare. In this study, the relative experiments were performed for analysis and discussion. In the static triaxial tests (CU test) of cement treated sand, the shear strength was improved. Then, to understand the development of excess pore water pressure with time, we performed a series of static triaxial creep tests. The test results showed that adding cement can decrease the development of excess pore water pressure. Use these experimental data to draw graphics, then a set of equations of dilatancy coefficient with time for different cement contents were obtained. Through these equations, the excess pore water pressure of cement treated sand applying a constant axial load for a long period can be obtained. Then, performed a series of step loading static triaxial tests, and compared the test results with the calculated values, and good consistency was obtained. The equations can be used as a practical estimation of excess pore water pressure with time. Finally, a cyclic triaxial test was performed to compare with the development of excess pore water pressure of static triaxial test (CU test). Negative values of excess pore water pressure were found in a rapid loading.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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