| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 101 === Unsaturated soil theories have been the focus of many studies in the past few decades. Numerous models regarding the shear strength of unsaturated soils have been proposed during the development process. Based on the former studies, the corresponding test approaches and their apparatus have also been well developed. In specific, the extended Mohr-Coulomb model proposed by Fredlund (1978) and the suction stress model proposed by Lu and William (2006) are the focus of this study. Both theories require the unsaturated shear strength parameters obtained by conducting the unsaturated strength test. However, it is often difficult to conduct, time consuming and requires special apparatus. Thus, it may be not considered as the practical experiment in the engineering field.
A new method that adopts two of the unsaturated theories mentioned above is therefore established in this study to estimate the apparent cohesion of unsaturated soils. It mainly utilizes the conventional tests with some assumptions and specified calculation processes. This new method is applied to the colluvial soil collected from Shaluntz to investigate the unsaturated shear strength properties and to evaluate the difference of the results obtained from various methods.
The apparent cohesions and the suction stresses calculated for the studied colluvial soil show reasonable trends and are consistent with the studies of former researches. Although the comparison to the unsaturated triaxial test result is still essential in order to verify the accuracy and the feasibility for the engineering application, the potential of this proposed method is still promising in the future.
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