A Numerical Study on the Influence of Initial Changes in Saturation of the Nonwetting Fluid on Consolidation of Unsaturated Porous Media

• Main Authors: Ming-CheHsu, 徐民哲
• Other Authors: Wwi-Cheng Lo
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/71794414464526475982

碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 100 === In the present study, a numerical study was performed to investigate the influence of initial changes in saturation of the nonwetting fluid on the consolidation behaviors of an elastic unsaturated porous medium. The analytical solution for a one-dimensional problem was derived based on the poroelasticity model of Lo et al. [2005] and the linear stress-strain relationship for a two-fluid system. The unsaturated porous skeleton examined here is assumed to have a free drainage surface on its top and base, and to be acted by constant external loadings, the interstices of which is permeated by two immiscible, viscous, compressible fluids, i.e. air and water. Eleven different soil textures, listed by Rawls et al. [1992], were selected for the determination of the dimensionless pore pressure and soil settlement with respect to the initial changes in saturation of the nonwetting fluid and initial saturation of the wetting fluid. Our numerical results show that the dimensionless pore pressure dissipates faster as the initial changes in saturation of the nonwetting fluid is greater. The same trend is also observed for the soil settlement. The dissipation of the dimensionless pore pressure is more obvious (e.g. Silty clay loam, Silty clay, and Clay) as the initial saturation of the wetting fluid is smaller, in which soil settlement is also more significant (e.g. Silty clay, and Clay). The dimensionless pore pressure dissipates slower as the initial saturation of the wetting fluid is greater, in which soil settlement also tends faster to achieve stable. The phenomenon is observed to be mainly dominated by the difference of viscosity coefficient of pore fluids. It is also revealed that the dimensionless pore pressure dissipative rate is positively correlated with the permeability coefficient at the initial stage, and at the later stage it has to simultaneously consider the permeability coefficient and bulk modulus of solid matrix. Soil settlement is seen to be negatively correlated with the bulk modulus of solid matrix.