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Experimental Study on the Effect of Entrapped Air on Quasi-saturated Soil Permeability

Author: WuZhengGuang
Tutor: ZhangHua
School: Three Gorges University
Course: Geotechnical Engineering
Keywords: Water Infiltration of the one-dimensional Closed bubbles Nearly saturated soil Permeability coefficient Experimental study
CLC: TU46
Type: Master's thesis
Year: 2010
Downloads: 34
Quote: 0
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Abstract

Infiltration is the process of moisture into the soil, infiltration problem is an important branch of soil mechanics. Process into the soil, the moisture in the most of the air electrode may be enclosed in the pores of the soil to form a closed bubbles hinder the flow of the aqueous phase, so that the permeability of the soil decreased, thus, the infiltration capacity of the soil to produce non overlook. Therefore, research in the ponded infiltration process Middle-earth pore closed cell content and its impact factors the entrapped air permeability of the soil, is conducive to a more comprehensive analysis of the soil infiltration capacity, for the study of water literature, farmland hydraulics and water quality environmental science and other disciplines have important guiding significance. In this paper, the indoor one-dimensional ponded infiltration test, mainly to carry out the following work: 1, making the indoor one-dimensional hydrocephalus test model, ponded infiltration test by the one-dimensional wetting front advancing process curve observed Since the closed bubbles surface soil present in the obvious stepped moisture distribution phenomenon, and further analyzes the causes of the closed cell of the soil body. 2, analysis of the the ponded infiltration within the soil column enclosed bubble volume and soil column dry density, and the relationship between the nature of the initial moisture content and soil type, and to explore the mechanism of three influencing factors on the impact of the enclosed volume of the air bubble. Ponded infiltration test based on the indoor one-dimensional data analysis of the dry density of the soil column, the nature of the initial moisture content and soil type on soil infiltration rate, Infiltration stable permeability coefficient and initial fitting volumetric water content of the empirical formula, and infiltration stable permeability coefficient with the empirical formula of the gas saturation, and further analysis of the mechanism of the closed bubble effects on the permeability coefficient and reduced infiltration. 4, using pressure membrane instrument measurement with one-dimensional stagnant water infiltration soil parameters on the same sample of soil water characteristic curve and measured soil water characteristic curve fitting Fredlund Xing model for one-dimensional plot Numerical simulation analysis of water infiltration. SEEP / W 2D seepage analysis software ponded infiltration of the one-dimensional numerical simulation analysis, results show that: the use of the test to obtain the soil water characteristic curve and the saturated permeability coefficient, SEEP / W calculation results with the measured one-dimensional the ponded infiltration wetting front to promote the process. Analysis of the reasons for the deviation of the simulation results, the SEEP / W seepage analysis theory does not consider closed bubbles that gas relative impact of soil pore water pressure, closed using Darcy's law does not consider the impact of bubbles on the permeability coefficient. Therefore, the numerical simulation of one-dimensional ponded infiltration need to consider closed bubbles of water phase flow.

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