軟弱粘土主要壓密中之壓縮性參數之研究

A Study on the Compressibility Parameters of Soft Clay during Primary Consolidation

曹力夫(Li-Fa Tsao)

指導教授 ： 馮道偉

中原大學/工學院/土木工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200469

摘要

摘 要
當土壤承受荷重，如興建結構物或填土時，會發生變形，而低滲透性的軟弱黏土壓密變形行為與時間相關。Taylor 和Merchant於1940年提出了一維壓密組合方程式，其中假設土壤孔隙比僅為有效應力及時間之函數，該方程式包含兩個壓縮性參數 及 ，分別描述在主壓密過程中的和有效應力相關的壓縮性及和時間相關的壓縮性。Mesri和共同研究者曾對此二參數進行研究，其中最主要的成果是獲得等向壓密條件下 及 之數據，並驗證了Taylor 和Merchant的壓密組合方程式，但尚未了解此二壓縮性參數之特性。
本研究主要是進行四聯式單向度壓密試驗來獲得軟弱粘土在主壓密過程中之 及 值，並探討此二參數在主壓密過程中的行為。由試驗所獲得之結果中應變率（ ）實測值及計算值之間具有良好的一致性，達到驗證壓密組合方程式的目的，此外觀察壓縮性參數在主壓密過程中並非維持常數，其變化的趨勢： 在主壓密初期具較大之變化量，之後則漸趨平緩； 則會隨應變增加至一最大值後開始遞減。

關鍵字

軟弱粘土 ； 壓縮性參數 ； 壓密 ； 主要壓密

並列摘要

Abstract
When a soil layer is subjected to an imposed load, such as during the construction of a structure or fill, deformation will occur. Consolidation behavior of soft clay with low permeability is highly dependent on time. Taylor and Merchant proposed a constitutive equation of one- dimensional consolidation in 1940, which contains two compressibility parameters, i.e. with respect to effective stress, , and with respect to time, , during primary consolidation. Mesri and co-workers have studied these two compressibility parameters, and the most important achievements were a collection of the data of and under isotropic consolidation condition and confirmation of the validity of the constitutive equation by Taylor and Merchant. However, the characteristic of these two compressibility parameters is still in question.
The purposes of this study are to obtain the compressibility parameters of and of soft clay during primary consolidation and to discuss the behavior of these two compressibility parameters. Four oedometers connected in series are used to observe consolidation process of soft clay specimens. According to the test results, there is well consistency between the measured and computed strain rate ( ). Furthermore, compressibility parameters do not remain constant during primary consolidation, i.e. increases rapidly in early part of the primary consolidation stage and decreases with time, and increases to a maximum value with the increase in strain and then decrease.

並列關鍵字

Compressibility Parameters ； consolidation ； Primary Consolidation ； Soft Clay

參考文獻

1. 李宜娟，民國九十年，"以分離式單向度壓密宜研究主壓密過程中之壓縮性參數"，私立中原大學土木工程系碩士論文。

3. Taylor, D. W. and Merchant, W. (1940), "A theory of clay consolidation accounting for secondary compression." Jour. of Mathematics and Physics, 19 (3), pp. 167-185.

5. Vaid, Y. P., Robertson, P. K. and Campanella, R. G. (1979), " Strain Rate Behavior of Saint-Jean-Vianney Clay." Canadian Geotechnical Jour.,16, pp. 34-42.

6. Mesri, G. and Choi, Y. K. (1979), " Strain Rate Behavior of Saint-Jean-Vianney clay：Discussion." Canadian Ceotechnique, Jour., 16 (4), pp. 831-834.

8. Mesri, G., Feng, T. W. (1986), Discussion "Stress-Strain-Strain Rate Relation for the Compressibility of Sensitive Natural Clays." by Leroueil et al., Geotechnique Vol. 36, No. 2, pp. 283-290.