A numerical model of infiltration processes for hysteretic flow coupled with mass conservation

Tan, Yih–Chi; Ma, Kuo‐Chen; Chen, Chu–Hui; Ke, Kai-Yuan; Wang, Ming-Tsan

doi:10.1002/ird.403

Cited by 9 publications

(11 citation statements)

References 9 publications

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“…The soil below the critical point is under wetting, whereas a monotonic drying process occurs above the critical point. The critical depth is not constant, but moves downward with time (Tan et al, 2009). The lower soil is still depicted using a single wetting scanning curve, but different drying scanning curves (dashed lines) along depths denoting the upper soil drying are shown in Fig.…”

Section: Hysteresis Analysismentioning

confidence: 99%

“…The critical depth is not constant, and moves downward with simulation time (Tan et al, 2009). The critical point for wetting and drying processes at time t is determined by the intersection point between the two analytical solutions using α d ' and α w ', which represent monotonic wetting and drying scanning curves, respectively.…”

Section: Relationship Between Permeability Coefficient and Matric Smentioning

confidence: 99%

“…A reversal criterion for drying and wetting is met when the pore-water pressure increment change its sign at any node and time step, which is easy to identify in a numerical program (Tan et al, 2009). At t' (t 0 < t' < t 1 ) the solution using monotonic drying curves is plotted in Fig.…”

Section: Hysteresis Analysismentioning

confidence: 99%

“…Hysteresis in soil-water characteristics, however, has not been included in all these analytical solutions. An analytical solution considering hysteresis has seldom been found although Tan et al (2009) is the first to present a numerical solution incorporating a hysteresis model. The objectives of this paper are to utilize an exponential model to describe the hysteresis in SWCC and permeability functions and to derive a 1D analytical solution to the governing equation for unsaturated porous media considering hysteresis.…”

Section: Introductionmentioning

confidence: 98%

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Incorporating hysteresis in one-dimensional seepage modeling in unsaturated soils

Huang

2011

KSCE J Civ Eng

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To understand better the influence of soil-water characteristic hysteresis on rainfall infiltration and pore-water pressure distributions in unsaturated soils, an analytical solution to the one-dimensional governing partial differential equation considering hysteresis is derived using a Fourier integral transformation. The analytical solution considers time-dependent and arbitrary initial pore-water pressure distributions, as well as a time-varying rainfall flux process at the ground surface. An exponential function is used to represent the hysteretic Soil-Water Characteristic Curve (SWCC) and the relationship between hydraulic conductivity and pore-water pressure. The calculated results demonstrate that the critical point, the intersection between wetting and drying domains in one-dimensional unsaturated seepage, is influenced by many factors. The hysteresis in soil-water characteristics is an important factor in infiltration process influencing the pore-water pressure profiles in unsaturated soils. The effects of hysteretic parameters on pore-water pressure profiles are also analyzed. The value of α in the hysteresis model is found to be the most significant factor influencing the pore pressure distributions.

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Section: Hysteresis Analysismentioning

confidence: 99%

Section: Relationship Between Permeability Coefficient and Matric Smentioning

confidence: 99%

Section: Hysteresis Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Incorporating hysteresis in one-dimensional seepage modeling in unsaturated soils

Huang

2011

KSCE J Civ Eng

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“…The complete operations and the validation of the numerical simulator about the infiltration model refer to the full paper published by Tan et al , 2009. The traditional numerical arithmetic for the unsaturated flow equation can be substantially improved using a simple mass conservation approximation and the hysteresis model.…”

Section: Infiltration Modelmentioning

confidence: 99%

The influence of water retention curve hysteresis on the stability of unsaturated soil slopes

Tan

Chen

2011

Hydrological Processes

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Abstract:Hysteresis is a common feature exhibited in hydraulic properties of an unsaturated soil. The movement of wetting front and the hysteresis effect are important factors which impact the shear strength of the unsaturated soil and the mechanics of shallow landslides. These failures are mainly triggered by the deepening of the wetting front accompanied by a decrease in matric suction induced by infiltration. This research establishes a method for determining a stability analysis of unsaturated infinite soil slopes, integrating the influence of infiltration and the water retention curve hysteresis. Furthermore, the present stability analysis method including the infiltration model and the advanced Mohr-Coulomb failure criterion calculates the variations of the safety factor (FS) in accordance with different slope angle, depth and hydrological processes. The experimentally measured data on the effect of hysteresis are also carried out for comparison. Numerical analyses, employing both wetting and drying hydraulic behaviour of unsaturated soil, are performed to study the difference in soil-water content as observed in the experiments. The simulating approximations also fully responded to the experimental data of sand box. The results suggest that the hysteresis behaviour affect the distribution of soil-water content within the slope indeed. The hysteresis made the FS values a remarkable recovery during the period of non-rainfall in a rainfall event. The appropriate hydraulic properties of soil (i.e. wetting or drying) should be used in accordance with the processes that unsaturated soil actually experience. This method will enable us to acquire more accurate matric suction head and the unsaturated soil-shear strength as it changes with the hysteretic flow, in order to calculate into the stability analysis of shallow landslides. An advanced understanding of the process mechanism afforded by this method is critical to realizing a reliable and appropriate design for slope stabilization. It also offers some immediate reference information to the disaster reduction department of the government.

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Characterizing the hydraulic properties of unsaturated sand considering various porosities and drying‐wetting paths of the retention curve

Tan

Chen

et al. 2012

Hydrological Processes

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Previous studies have shown that water retention curve (WRC) and the hydraulic conductivity vary because of changes of the void ratio or porosity of soil. However, limited documents pointed out the change of hydraulic properties of soil when compacted to different porosities while considering both of the drying and wetting processes of the WRC. This information is sometimes necessary for research like finger flow analysis or the occurrence of wetting and drying cycles as what would be seen in the field. Therefore, this study aims to examine the change of WRC characteristics with varied porosity considering both of the drying and wetting path in WRC by conducting a sand box experiment. Results show that the same type of sand compacted to various porosities have different hydraulic parameters. Hydraulic conductivities generally decrease with reduced porosities; shape parameter α of the van Genuchten equation (1980) linearly decreases with declining porosity and shape parameter n in a reversal manner for the sands of interest whether in the drying process or wetting process. The unsaturated properties of sand are further characterized by inspecting the variations of moisture content, matric suction and vertical displacement of soil body subject to periodic changes of the water level by another sand box experiment. The outcomes suggest that the saturated water content and residual water content are changing during the wetting–drying process, which can be an implication of the changed properties of WRC. The characteristics of volumetric deformation might be varied as well because of the observation of the dissimilar patterns of the changing vertical displacements among each wetting–drying process. Infiltration patterns of the sands also are identified through numerical modelling by introducing a constant infiltration flux from the surface followed by a no‐influx condition. Results indicate that less water accumulates in the sand near the surface for the sand compacted to higher porosity, but water can move deeper. Hydraulic conductivity is found as the prime factor dominating the evolvement of wetting fronts. However, shape parameters of water retention curves also affect the infiltration pattern to some extent. In addition, different sands with similar porosities can have quite different infiltrating characteristics. Copyright © 2012 John Wiley & Sons, Ltd.

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A numerical model of infiltration processes for hysteretic flow coupled with mass conservation

Cited by 9 publications

References 9 publications

Incorporating hysteresis in one-dimensional seepage modeling in unsaturated soils

Incorporating hysteresis in one-dimensional seepage modeling in unsaturated soils

The influence of water retention curve hysteresis on the stability of unsaturated soil slopes

Characterizing the hydraulic properties of unsaturated sand considering various porosities and drying‐wetting paths of the retention curve

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