| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 94 === Since Terzaghi (1923) proposed the theory of consolidation for saturated soils, the study of the problem concerning field soil settlements has been conducted successfully and showed its importance in many engineering problems. Conversely, the research on unsaturated soils only receives limited attention. This thesis focuses on the issue of consolidation of unsaturated soils by applying the theoretical results of Tuncay and Corapcioglus (1996) from the method of microscopic volume-averaging. The soil skeleton examined here is assumed to have a free drainage surface on its top and an impervious surface on its base. Since lateral displacements are typically much smaller as compared to vertical displacements during the process of consolidation, the problem of one dimensional representation is considered in the present study. The hydraulic and elastic parameters of eleven soils listed by Rawls (1992) were used as illustrative examples. Numerical results to model dimensionless induced pore pressure, induced saturation of the air phase, porosity change, and the total settlement in response to an applied stress were presented. It is concluded that all these physical parameters have a close relation to the bulk modulus and permeability of soils. Among the eleven soils, sand is most prone to squeeze the pore fluids. The amount of fluid expelled diminishes as the permeability decreases. On the other hand, clay settles largest. When the bulk modulus becomes greater, the settlement decreases more. The porosity was found to have the same trend as the amount of the settlement. The results observed from dimensionless induced pore pressure reveal that when the pore space contains more water, it has a better ability to bear the stress which acts on the top. Accordingly, the dissipation of the dimensionless pore pressure is not obvious. In reference to the behavior of the air phase, we see that it is affected both by the bulk modulus and permeability of soils. Lastly, it is found the consolidation in the upper part of soils is closely related to the bulk modulus whereas that in the lower part is dominant by the permeability.
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