Numerical analysis of 1D coupled infiltration and deformation in layered unsaturated porous medium

Wu, Lizhou; Liu, G. G.; Wang, L. C.; Zhang, Li Min; Li, B. E.

doi:10.1007/s12665-016-5579-4

Cited by 25 publications

(24 citation statements)

References 28 publications

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“…From Table 5, the final correlation is calculated by computing the average value, which is: τ (kPa) = 30.482 − 0.385β (deg.) + 0.617σ (kPa) (9) and the average R 2 comes out to be 99.5%.…”

Section: Saturated Seismic Analysismentioning

confidence: 92%

“…Another researcher examined laboratory, field tests and the study of specific, large and accessible data based on 49 different landslides caused by the worst rainfall events in northern Australia and gave an indication of possible earthquake-induced landslide sites in the future [7]. Numerous quantitative studies have been conducted to investigate infiltration issues [8,9]. Some other researchers have also studied the limits on the stability analysis of the soil slope under rainfall [10].…”

Section: Introductionmentioning

confidence: 99%

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Slope Stability Analysis to Correlate Shear Strength with Slope Angle and Shear Stress by Considering Saturated and Unsaturated Seismic Conditions

Khan

Wang

2021

Applied Sciences

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Assessment and analysis of soil slope stability is an important part of geotechnical engineering at all times. This paper examines the assessment of soil slope stability in fine-grained soils. The effect of change in shear strength (τ), shear stress (σ) and slope angle (β) on the factor of safety has been studied. It correlates shear strength with slope angle and shear stress by considering the horizontal seismic coefficients in both saturated and unsaturated conditions. The slope failure surface was considered a circular slip surface. Statistical package for social sciences (SPSS) and Slide, numerical modeling software and limit equilibrium slope stability analysis software, respectively, are used to find out the correlations between the three basic parameters. The slope angle varied from 70 to 88 degrees, which are the most critical values for slope angles, and a total of 200 analyses were performed. τ, β and σ are correlated, and the correlations are provided in the results section. The results indicate that the correlations developed between the parameters have a very close relationship. The applicability of the developed equations is above 99%. These correlations are applicable in any type of soil slope stability analysis, where the value of shear strength and factor of safety is required with the variation of slope angle and shear stress.

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Section: Saturated Seismic Analysismentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Slope Stability Analysis to Correlate Shear Strength with Slope Angle and Shear Stress by Considering Saturated and Unsaturated Seismic Conditions

Khan

Wang

2021

Applied Sciences

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“…The bottom boundary condition is groundwater table, defined as   0, 0 h z t  . The top boundary condition is given by (Wu et al 2016):…”

Section: Application Examplesmentioning

confidence: 99%

An Improved Picard Iteration Scheme for Simulating Unsaturated Flow in Layered Porous Media

Zhu

2021

Preprint

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Picard iteration method is commonly used to obtain numerical solution of unsaturated flow in porous media. However, because the system of linear equations derived from Richards equation is seriously ill-conditioned, Picard iteration has slow convergence rate and low computational efficiency, particularly in layered porous media. In this study, control volume method based on non-uniform nodes is used to discrete Richards equation. To improve the convergence rate of Picard iteration, we combine the non-uniform multigrid correction method with the multistep preprocessing technology. Thus, an improved Picard iteration scheme with multistep preconditioner based on non-uniform multigrid correction method (NMG-MPPI(m)) is proposed to model 1D unsaturated flow in layered porous media. Three test cases were used to verify the proposed schemes. The result shows that the condition number of the coefficient matrix has been greatly reduced using the multistep preconditioner. Numerical results indicate that NMG-MPPI(m) can solve Richards equation at a faster convergence rate, with higher calculation accuracy and good robustness. Compared with conventional Picard iteration, NMG-MPPI(m) shows a very high speed-up ratio. As a result, the improved Picard iteration scheme has good application for simulating unsaturated flow in layered porous media.

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“…Many geotechnical engineering problems involve unsaturated seepage, such as the soil slope stability and dam infiltration involved in rainfall or groundwater changes, and the transportation of pollutants in landfill (Morway et al, 2013;Ku et al, 2017;Li et al, 2020). Therefore, effectively simulating and analyzing unsaturated seepage is of great practical significance (Wang et al, 2011;Zang et al, 2016;Wu et al, 2016;2020a). The Richards equation (RE) provides a basic description of unsaturated infiltration (Richards, 1931), although analytical solutions to the RE are difficult to derive.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, other advanced numerical methods for solving variable saturated flow problems exhibit high levels of accuracy, computational efficiency, or ease of implementation under certain conditions. These include the two-level adaptive domain decomposition (Kuraz et al, 2015), finite analytic method (Zhang et al, 2016), and Chebyshev's spectral method (Wu et al, 2020b). A system of linear equations derived from the RE need to be solved iteratively, such as by using the Picard iteration (PI) scheme.…”

Section: Introductionmentioning

confidence: 99%

Modelling Unsaturated Flow in Porous Media Using an Improved Picard Iteration Scheme

Zhu

2021

Preprint

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The numerical solution of various systems of linear equations describing fluid infiltration uses the Picard iteration (PI). However, because many such systems are ill-conditioned, the solution process often has a poor convergence rate, making it very time-consuming. In this study, a control volume method based on non-uniform nodes is used to discretize the Richards equation, and adaptive relaxation is combined with a multistep preconditioner to improve the convergence rate of PI. The resulting adaptive relaxed PI with multistep preconditioner (MP(m)-ARPI) is used to simulate unsaturated flow in porous media. Three examples are used to verify the proposed schemes. The results show that MP(m)-ARPI can effectively reduce the condition number of the coefficient matrix for the system of linear equations. Compared with conventional PI, MP(m)-ARPI achieves faster convergence, higher computational efficiency, and enhanced robustness. These results demonstrate that improved scheme is an excellent prospect for simulating unsaturated flow in porous media.

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Numerical analysis of 1D coupled infiltration and deformation in layered unsaturated porous medium

Cited by 25 publications

References 28 publications

Slope Stability Analysis to Correlate Shear Strength with Slope Angle and Shear Stress by Considering Saturated and Unsaturated Seismic Conditions

Slope Stability Analysis to Correlate Shear Strength with Slope Angle and Shear Stress by Considering Saturated and Unsaturated Seismic Conditions

An Improved Picard Iteration Scheme for Simulating Unsaturated Flow in Layered Porous Media

Modelling Unsaturated Flow in Porous Media Using an Improved Picard Iteration Scheme

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