| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 107 === It is widely known that overexploiting groundwater resources will lead to severe land subsidence. Land subsidence does not only lead to flood risk, but also endanger rail transit operations. In recent years, urban development has grown rapidly due to the need of industry, transportation, housing, and etc. In the process of urbanization, natural land surfaces are replaced by impervious pavement and buildings. In addition, the process of industrial rapidly development thereby makes abnormal climate influence the precipitation. Therefore, the change of the infiltration makes land subsidence problems become more complicated. Most research on this topic has shown that decreases in groundwater levels are the primary cause of land subsidence. However, soil consolidation is affected by infiltration in the vadose zone, and this is also a crucial factor related to land subsidence. Based on the poroelasticity theory of consolidation in unsaturated soils developed by Lo et al. (2014), the analytical solutions formulated for a one‐dimensional consolidation of single‐layer unsaturated soils subject to a flux boundary condition are presented in this study, in which we assume different forms of infiltration on the top of the soil sample and free drainage on its base. In addition, we discussed the unsaturated soil consolidation process for different types of soils with different initial saturation levels. Our results shows that the response to excess pore pressure and total settlement under the infiltration boundary is dominated by the intrinsic permeability and initial saturation levels of unsaturated soils. In addition, the time required for pressure and settlement to achieve dynamic equilibrium is significantly related the form of infiltration. Infiltration has a great impact on subsidence. Accordingly, change in infiltration caused by human activities is of considerable importance to land subsidence problems.
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