Analysis of multi-phase coupled seepage and stability in anisotropic slopes under rainfall condition

Wu, L. Z.; Zhang, Li Min; Zhou, Yingxin; Li, B.E.

doi:10.1007/s12665-017-6811-6

Cited by 29 publications

(28 citation statements)

References 39 publications

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“…Numerical techniques for analyzing coupled water infiltration and deformation in partially saturated porous media are being increasingly utilized because rainfall infiltration involves complicated geometries, soil heterogeneity, and complex spatial and temporal boundary conditions [16]. Analytical approaches to such practical situations are difficult [17].…”

Section: Geofluidsmentioning

confidence: 99%

The Role of Surface Infiltration in Hydromechanical Coupling Effects in an Unsaturated Porous Medium of Semi-Infinite Extent

Selvadurai

Yang

2017

Geofluids

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Rainfall infiltration into an unsaturated region of the earth's surface is a pervasive natural phenomenon. During the rainfall-induced seepage process, the soil skeleton can deform and the permeability can change with the water content in the unsaturated porous medium. A coupled water infiltration and deformation formulation is used to examine a problem related to the mechanics of a two-dimensional region of semi-infinite extent. The van Genuchten model is used to represent the soil-water characteristic curve. The model, incorporating coupled infiltration and deformation, was developed to resolve the coupled problem in a semi-infinite domain based on numerical methods. The numerical solution is verified by the analytical solution when the coupled effects in an unsaturated medium of semi-infinite extent are considered. The computational results show that a numerical procedure can be employed to examine the semi-infinite unsaturated seepage incorporating coupled water infiltration and deformation. The analysis indicates that the coupling effect is significantly influenced by the boundary conditions of the problem and varies with the duration of water infiltration.

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Section: Geofluidsmentioning

confidence: 99%

The Role of Surface Infiltration in Hydromechanical Coupling Effects in an Unsaturated Porous Medium of Semi-Infinite Extent

Selvadurai

Yang

2017

Geofluids

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“…Although numerous empirically based approaches have been widely applied to large areas using simple methods, deterministic physics-based approaches are preferable for a better understanding of the mechanisms of shallow landslides [13]. Numerous physically based studies have investigated infiltration behavior during rainfall using various approaches: (1) Adopting assumptions for simplification to solve the differential equation of Richards [14] by applying a single-phase fluid (water) flow [3,10,15,16]; (2) assuming that the air pressure in the void spaces of an unsaturated soil slope is equal to the atmospheric pressure [9,17,18]; (3) applying a two-phase fluid (water and air) flow [19][20][21][22][23]; and (4) considering hydraulic hysteresis, including the effects of capillarity and/or air entrapment, reflecting different hydraulic states under wetting and drying conditions [24,25]. Such physically based numerical studies have mainly been applied at slope or watershed scales.…”

Section: Introductionmentioning

confidence: 99%

“…Several experiments and interpretations have reported that the air flow generated during infiltration changes the rate of the infiltrating water, affecting the safety factor. Therefore, it is apparent that the effect of air on the subsurface flow of fluids is relevant and should be included in infiltration analysis [21,22,35,36].…”

Section: Introductionmentioning

confidence: 99%

Effects of Two-Phase Flow of Water and Air on Shallow Slope Failures Induced by Rainfall: Insights from Slope Stability Assessment at a Regional Scale

Kang

Cho

Kim

et al. 2020

Water

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Over 160 shallow landslides resulted from heavy rainfall that occurred in 26–27 July 2011 at Umyeon Mountain, Seoul, South Korea. To accurately reflect the fluid flow mechanism in the void spaces of soils, we considered the two-phase flow of water and air for rainfall infiltration analysis using available historical rainfall data, topographic maps, and geotechnical/hydrological properties. Variations in pore water and air pressure from the infiltration analysis are used for slope stability assessment. By comparing the results from numerical models applying single- and two-phase flow models, we observed that air flow changes the rate of increase in pore water pressure, influencing the safety factor on slopes with a low infiltration capacity, where ponding is more likely to occur during heavy rainfall. Finally, several slope failure assessments were conducted to evaluate the usefulness of using the two-phase flow model in forecasting slope stability in conditions of increased rainfall sums. We observed that the two-phase flow model reduces the tendency of over-prediction compared to the single-phase model. The results from the two-phase flow model revealed good agreement with actual landslide events.

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“…The change of the area from unsaturated to saturated is caused by the advancement of the wetting front from the surface [4,5,9,13,[21][22][23] and groundwater table from depth [6][7][8][10][11][12][13][14][15][16][17][18][19][20]. Those processes were found to be the primary factors controlling the instability of slopes due to rainfall and were greatly affected by rainfall intensity (RI) and soil properties, especially by unsaturated soil hydraulic conductivity [4,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. The unsaturated soil hydraulic conductivity (HC) controls the transient seepage, the depth of rainfall infiltration, the changes in pore pressure during the rainfall event, and finally, affects the FOS.…”

Section: Introductionmentioning

confidence: 99%

“…The unsaturated soil hydraulic conductivity (HC) controls the transient seepage, the depth of rainfall infiltration, the changes in pore pressure during the rainfall event, and finally, affects the FOS. The effects of soil hydraulic conductivity on slope stability in the rainy season are usually assessed from the point of view of three topics: (1) the effects of changes in the value of soil hydraulic conductivity and rainfall intensity [17][18][19][20][21][22][23][24][25][26][27][28][29][30]; (2) the soil anisotropic HC and hydraulic hysteresis [31][32][33][34][35]; (3) the failure delay phenomenon due to the defense of HC and RI [36]. This research focuses on the overview and analysis of the first of these topics.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Effects of Rainfall Intensity and Hydraulic Conductivity on Riverbank Stability

Duong

Yasuhara

2019

Water

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Riverbank failure often occurs in the rainy season, with effects from some main processes such as rainfall infiltration, the fluctuation of the river water level and groundwater table, and the deformation of transient seepage. This paper has the objective of clarifying the effects of soil hydraulic conductivity and rainfall intensity on riverbank stability using numerical analysis with the GeoSlope program. The initial saturation condition is first indicated as the main factor affecting riverbank stability. Analyzing high-saturation conditions, the obtained result can be used to build an understanding of the mechanics of riverbank stability and the effect of both the rainfall intensity and soil hydraulic conductivity. Firstly, the rainfall intensity is lower than the soil hydraulic conductivity; the factor of safety (FOS) reduces with changes in the groundwater table, which is a result of rainwater infiltration and unsteady state flow through the unsaturated soil. Secondly, the rainfall intensity is slightly higher than the soil hydraulic conductivity, the groundwater table rises slowly, and the FOS decreases with both changes in the wetting front and groundwater table. Thirdly, the rainfall intensity is much higher than the soil hydraulic conductivity, and the FOS decreases dominantly by the wetting front and pond loading area. Finally, in cases with no pond, the FOS reduces when the rainfall intensity is lower than hydraulic conductivity. With low hydraulic conductivity, the wetting front is on a shallow surface and descends very slowly. The decreasing of FOS is only due to transient seepage changes of the unsaturated soil properties by losing soil suction and shear strength. These obtained results not only build a clearer understanding of the filtration mechanics but also provide a helpful reference for riverbank protection.

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Analysis of multi-phase coupled seepage and stability in anisotropic slopes under rainfall condition

Cited by 29 publications

References 39 publications

The Role of Surface Infiltration in Hydromechanical Coupling Effects in an Unsaturated Porous Medium of Semi-Infinite Extent

The Role of Surface Infiltration in Hydromechanical Coupling Effects in an Unsaturated Porous Medium of Semi-Infinite Extent

Effects of Two-Phase Flow of Water and Air on Shallow Slope Failures Induced by Rainfall: Insights from Slope Stability Assessment at a Regional Scale

Assessing the Effects of Rainfall Intensity and Hydraulic Conductivity on Riverbank Stability

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