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1.Experimental Research on Network Characteristics of

作  者: ZHU Lei1, WANG Kang2, ZHOU Qing2
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: Iodine-starch staining; Preferential flow; Flow patterns
摘  要: Preferential flow refers to such a flow transport pattern that water and solute flows round the soil matrixes, which contributes to accelerate the movement velocity in the soil , and soil recharge happens on the whole inlet boundary. Preferential flow is produced by a large number of macropores and fractures in the soil, such as root and wormhole, so it is of great importance to groundwater recharge due to its quick movement .For knowing the process of infiltration recharge , evaluating the recharge source underground water and analysis of subsurface water pollution, it’s great significant to research the influence of preferential flow to soil moisture transport. In this study, according to the principle that iodine turns to blue after reacting with starch, outdoor tracer experiments of heterogeneous flow in clay loam are designed, from which the heterogeneous flow patterns are studied.

2.Research on the Application of Unsaturated Soil Water Migration SWCC Models

作  者: YANG Yong1,XUE Qiang2
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: unsaturated; soil water characteristic curve; numerical simulation; sensitivity analysis
摘  要: The soil water characteristic curve is very important for controlling movement of the unsaturated soil water. Based on the former models, this paper is simulated with the numerical simulation on Gardner-Simmons and Brooks-Corey and Van-Genuchten. The numerical results show that the VG model has a perfect flexibility in the soil water. At the same time, saturated water content and saturated infiltrate coefficient and residual water content are analyzed and discussed by the sensitivity analysis. The analysis results show that saturated infiltrate coefficient in those parameters is the most intensive than other parameters. Research on the parameters of water movement law can offer theory foundation for the measurement of the basic parameters in the laboratory and on the site.

3.Study on The Unsaturated Soil Water Extracting for Stable Isotope

作  者: CHEN Jiansheng 1,2, WANG Yongsen 3
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: soil water extracting; stable isotope ; fractionation
摘  要: Hydrogen and oxygen stable isotope is an important method for the study of the unsaturated soil water in the field of isotope hydrology. The soil water content is various at the different stage due to the influence of the precipitation infiltration and evaportranspiration. This paper designs the vacuum equipment for the soil water extraction, which avoids isotope fractionation of soil water in the extracting process. And the effects of the isotope seasonal variation in precipitation and soil surface evaporation on the soil water isotope are described which provide a method for the study of soil water movement.

4.A Mathematical Model for a Disturbed Soil-column Experiment and Reconstruction of Breakthrough Data*

作  者: LI Gongsheng1,2 , ZHANG Zongxin2 , YAO De2
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: Disturbed soil-column experiment; advection-dispersion equation; parameter inversion; optimal perturbation algorithm; data reconstruction
摘  要: This paper deals with a mathematical model for a disturbed soil-column experiment, and inversion and reconstruction of the measured breakthrough data. Based on the analysis of the experimental process and the breakthrough data for eight kinds of ion solutes, a mathematical model describing transport behaviors of the solute ions in the column was established. Furthermore, the unknown parameters were determined by applying an optimal perturbation iteration algorithm, and the breakthrough data were reconstructed.

5.Dynamic Modeling of Soil Moisture and Water Balance Analysis along Gentle Slope Upland in Southern China

作  者: JING Yuanshu 1, Alexander THIMM 2
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: Soil moisture, dynamic modeling, slope upland, water balance
摘  要: In order to study the soil moisture of peanut fields in the region of red soil and to develop water-saving agriculture along gentle slope upland in southern China , the numerical modeling of soil moisture dynamics was established, based on Richard movement equitation. The simulated soil moisture was in good agreement with measured data. Modeling analysis showed that the soil hydraulic parameters are more sensitive than other kind of parameters. The simulation also demonstrated that the cumulative evapotranspiration in the 150 ㎝ soil profile at upper slope is higher than lower slope. In conclusion, it’s advantageous for tillage soil at the lower slope to keep soil moisture and resist the drought in the peanut field during dry season in southern China. The numerical modeling of soil moisture has practical significance to improve the management of water capture and retention and development of water-saving agriculture.

6.A Study on the Mechanisms of Sand-layered Loess Interfering Rainfall Infiltration

作  者: WANG Ting , CHEN Jiansheng
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词:  sand-layered loess; rainfall infiltration; film water; preventing water
摘  要: The paper studies rainfall infiltration in the northwestern arid area. Laboratory experiments were conducted to confirm the sand-layered soil preventing water and the reason was shown theoretically. The results showed that the film water absorbed on the soil particle surface transferring is the main moisture migration way for the unsaturated ground-water in arid area where precipitation is very rare and the water always transfer from thick film to thin one. Film water flow capacity is positively related to the film water cross-section area. For the film water cross-sectional area of the sand layer is much smaller than the soil, so the film water retaining capacity of sand layer is far bigger than the soil. This is the basic reason why sand layer can prevent rainfall infiltration. This paper has discussed micro-mechanism about water-tightness of sand layered soil, and provided theoretical basis for “pressuring sand” phenomenon in northern area.

7.Isotopic Evolution in Evaporation Process of Certain Volume Soil Water

作  者: SUN Xiaoxu , CHEN Jiansheng
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词:  soil water evaporation, hydrogen oxygen isotopes, evolution rule, free water, vacuum pumping system.
摘  要:  Certain amount of oven-dried sand was doped with water having known isotopic composition. Using this method we prepared four groups soil water with different water contents. Evaporation process of certain volume soil water was simulated by the extraction in the vacuum pumping system. In the experiment, steam been evaporated from each sample was condensed and collected in four time segments and its hydrogen and oxygen isotopic compositions were determined. Based on the isotopic measured value of collected water and the law of mass conservation, isotopic evolution rules of steam and residual water were obtained in evaporation processes. In equilibrium evaporation process, the enrichment of hydrogen is about eight times of oxygen’s in the free water. Ian D.Clark had shown the steam and residual water’s isotopic evolution rules in evaporation process of the limited volume free water. In the test, the steam isotope is corresponding depleted which is contrary to the water initial isotopic composition in soil water evaporation process. And the isotopic compositions of steam and residual water are all on the soil water evaporation line. In initial stage of evaporation process the steam losses heavy isotopes, but its isotopic composition changes toward the initial water with the increasing of the steam ratio. From comparison, it is obtained that the two isotopic evolution rules are similar in free water and soil water evaporation processes. For sand soil, van der waals force to water molecular has little influence to soil water evaporation under the equilibrium condition.

8.Simulation of Heterogeneous Soil Water Flow Using the Active Region Model

作  者: WANG Kang , WU Jingfeng2
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: Active Region Model, Preference flow, Percolation
摘  要: Preferential flow in the unsaturated soil is an important and common phenomenon, which is difficult to be characterized. The objective of this paper is to evaluate the Active Region Model (ARM), which incorporated the fractal flow patterns into the continuum approach, has been developed to characterize preferential water flow in the unsaturated zone. Experiments were conducted to measure water flow process in a bare soil landfill cover and a ET landfill cover. Modeling analysis indicated that the water content distributions could be simulated generally well with the ARM by considering preferential flow in the porous media. Compared with the ARM, the continuum model underestimated percolation for both bare soil and vegetation coved plots.

9.The Simulation to Water Transport in Unsaturated Soils

作  者: LIU Peng , HUANG Ying
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词:  water, unsaturated soil, transport model, movement law
摘  要: Both water supply and substantive rainfalls course the water influent to unsaturated soil and change the water content. Base on conventional transport of unsaturated soil water,established the transport equation, and gave out model solving process. This model could forecast the movement law at unsaturated soil environment. Use the software Femlab simulated the change law about transport of unsaturated soil water in 10days. The result shows that the horizon and vertical water content is incessant increase with the time; Water content came along the distance water source increase whereas decrease; the farther to the distance water source, the smaller to the water content; water movement degree at penetrability well soil is greater than the penetrability poor soil, so transport of unsaturated soil water mostly focus on the penetrability well soil. Both toward handling problem about soil and water loss、pollution to surface water and groundwater、flood drought with water resources have theory supervise sense and operation significance.

10.Coupled Numerical Simulation of Slope Stability with Unsaturated Soil under Rainfall Condition

作  者: LI Jixiang1,2, LIU Xiaofan2, JIANG Zhaohua2
出  处: Flow in Porous Media — From Phenomena to Engineering and Beyond Conference Paper from 2009 International Forum on Porous Flow and Applications, Wuhan City, CHINA
书  号: 978-0-9806057-0-9
通过检索: ISTP,SEI
发表日期: 2009年04月
关 键 词: unsaturated soil slope, rainfall infiltration, coupled analysis, strength reduction method, numerical simulation
摘  要:  Rainfall is one of main factors that affect the slope stability. Rainfall infiltration will change the degree of saturation determination of soil, and further influence the pore water pressure and the permeability coefficient of the medium. Based on the saturated-unsaturated seepage theory and the effect of rainfall infiltration, coupled with two phase medium of unsaturated soil and water, numerical simulation of soil slope under rainfall condition is carried out using the strength reduction finite element method. Changes of the slope displacement, pore pressure and safety factor under different rainfall periods and rainfall intensities are discussed. This study can provide important data for the slope stability analysis and landslide prediction.
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