A 2D integrated FEM model for surface water–groundwater flow of slopes under rainfall condition

Tian, Dapeng; Zheng, Hong; Liu, De Fu

doi:10.1007/s10346-016-0716-4

Cited by 20 publications

(13 citation statements)

References 20 publications

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“…The connection between the surface run-off equation and the waterair two-phase flow equation is built by certain common parameters, such as the infiltration rate and boundary pressure (Camporese et al, 2010;Tian et al, 2017). The rainfall infiltration rate for the slope is mainly governed by the rainfall intensity, soil moisture content, soil infiltration capacity, and angle of the slope (Morbidelli et al, 2016).…”

Section: Solution Strategiesmentioning

confidence: 99%

“…To better understand the influence of the water-air two-phase flow in the slope on the surface run-off process, the simulation results are compared with those from the traditional surface-subsurface model, which is derived from Richards' equation. The coupled surfacesubsurface model of Tong (Tong et al, 2008), which consists of a kinematic wave equation for the surface water flow and Richards' equation for the ground water flow (Tian et al, 2017), is chosen for comparison with the proposed model, and the relevant calculation parameters are listed in Table 1. The pore air pressure in the slope is neglected by Tong's model, whereas the pore air pressure calculated by the new model is presented in Figure 8.…”

Section: Comparison With the Traditional Surfacesubsurface Modelmentioning

confidence: 99%

“…Studying the association between the two processes is important to understand the hydrologic cycle, the run‐off generation, and the transport of pollutants down a slope (Morbidelli et al, ). Most of the available integrated run‐off models of slope seepage and surface run‐off are derived from Richard's equation and hydrostatic shallow flow equations (Saint‐Venant equations and kinematic wave equations; Camporese, Paniconi, Putti, & Orlandini, ; Freeze, ; Muntohar & Liao, ; Querner, ; Tian & Liu, ; Tian, Zheng, & Liu, ; Tong, Tian, & Liu, ; VanderKwaak & Loague, ). Richard's equation, which assumes that the pore air pressure equals the atmospheric pressure, has been applied to simulate the seepage flow process on a slope (Richards, ).…”

Section: Introductionmentioning

confidence: 99%

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A finite element model for simulating surface run‐off and unsaturated seepage flow in the shallow subsurface

Liu

Tong

Tian

2019

Hydrological Processes

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This work introduces water-air two-phase flow into integrated surface-subsurface flow by simulating rainfall infiltration and run-off production on a soil slope with the finite element method. The numerical model is formulated by partial differential equations for hydrostatic shallow flow and water-air two-phase flow in the shallow subsurface. Finite element computing formats and solution strategies are presented to obtain a numerical solution for the coupled model. An unsaturated seepage flow process is first simulated by water-air two-phase flow under the atmospheric pressure boundary condition to obtain the rainfall infiltration rate. Then, the rainfall infiltration rate is used as an input parameter to solve the surface run-off equations and determine the value of the surface run-off depth. In the next iteration, the pressure boundary condition of unsaturated seepage flow is adjusted by the surface run-off depth. The coupling process is achieved by updating the rainfall infiltration rate and surface run-off depth sequentially until the convergence criteria are reached in a time step. A well-conducted surface run-off experiment and traditional surface-subsurface model are used to validate the new model. Comparisons with the traditional surface-subsurface model show that the initiation time of surface run-off calculated by the proposed model is earlier and that the water depth is larger, thus providing values that are closer to the experimental results. K E Y W O R D S integrated surface-subsurface flow modeling, rainfall infiltration, surface run-off, water-air two-phase flow

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Section: Solution Strategiesmentioning

confidence: 99%

Section: Comparison With the Traditional Surfacesubsurface Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A finite element model for simulating surface run‐off and unsaturated seepage flow in the shallow subsurface

Liu

Tong

Tian

2019

Hydrological Processes

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“…Generally, rainfall infiltration into slopes increases pore water pressure or reduces soil suction (especially in unsaturated soil slopes); the continual drop of the shear strength of soil significantly contributes to the failure of slopes during rainfall. Studies on rainfall-induced landslides or slope stability during rainfall have been conducted in different ways such as numerical analyses on the slope stability during rain infiltration (Cho and Lee 2001;Qi and Vanapalli 2015;Cai and Ugai 2004;Sharma and Nakagawa 2010;Tian et al 2017), large/small-scale model experiments (Wang and Sassa 2001;Montrasio and Valentino 2004;Sharma and Nakagawa 2010), field tests (Ng et al 2003;Springman et al 2013;Rahardjo et al 2005;Chen et al 2018), and centrifuge model tests (Take et al 2004;Tamate et al 2012;Bhattacherjee and Viswannadham 2018). These methods provided valuable guidance on landslide-related research and have been adopted by numerous researchers to investigate the response of slopes to earthquakes or rainfall.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of failure of slopes with shaking-induced cracks in response to rainfall

Ueda

Uzuoka

2021

Landslides

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Centrifuge model tests on slopes subject to shaking and rainfall have been performed to examine the response of slopes with shaking-induced cracks to subsequent rainfall and evaluate the corresponding landslide-triggering mechanisms. The failure pattern of the slope subject to shaking and then rainfall was found different from that of the slope subject to only rainfall. When shaking caused cracks on the slope shoulder and rupture line below, the mobilized soil slid along the slip surface that extended to the rupture line, the main crack became the crown of the undisturbed ground once the slope was subject to a subsequent rain event, and the progression of the landslide was related to the rainfall intensity. During the landslide caused by light rainfall, the main scarp kept exposing itself in the vertically downward direction while the ground behind the main crack in the crack-containing slope remained undisturbed. The detrimental effect of cracks on soil displacement was more evident when the slope was exposed to heavy post-shaking rainfall, resulting in a rapid and massive landslide. Additionally, the volume of displaced material of the landslide, the main scarp area on the upper edge, and the zone of accumulation were larger in the crack-containing slope subject to heavy rainfall, in comparison with those in the crack-free slope. The deformation pattern of slopes with shaking-induced cracks during rainfall was closely related to rainfall intensity and the factor of safety provided a preliminary estimation of slope stability during rainfall. Moreover, even when subjected to the same rainfall, the slopes with antecedent shaking-induced cracks displayed different levels of deformation. The slope that experienced larger shaking had greater deformation under the following rainfall, and the shaking-induced slope deformation also controlled the slip surface location. Finally, the velocity of rainfall-induced landslide could be greatly influenced by the prior shaking event alone. Despite being under light rainfall, the slope that has encountered intense previous shaking exhibited an instant landslide.

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“…Therefore, the underlying physical phenomenon of the coupled runoff and seepage should be investigated in-depth [16]. Tian et al believed that slope stability evaluation should consider the impact of runoff on rainfall infiltration [17]. Some coupled models of runoff and seepage have been proposed [18,19], where Slope Runoff (SR) was described by kinematic wave equation or diffusion wave equation, and UF was described by the Richards equation [20][21][22] with the finite difference method [23][24][25] or finite element method and the corresponding solving programs have been compiled [17,20,21,26].…”

Section: Introductionmentioning

confidence: 99%

Water Field Distribution Characteristics under Slope Runoff and Seepage Coupled Effect Based on the Finite Element Method

Jiang

Que

et al. 2021

Water

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The unsaturated seepage field coupled with heavy rainfall-induced surface flow mainly accounts for the slope instability. If the slope contains macropores, the coupled model and solution process significantly differ from the traditional one (without macropores). Most of the studies on the variation of the water field under the coupled effect of runoff and seepage on the slope did not consider the macropore structure. In this paper, two coupled Richards equations were used to describe the MF (Macropore Flow), and along with the kinematic wave equation, they were applied to establish a coupled model of SR (Slope Runoff) and MF. The numerical solving of the coupled model was realized by the COMSOL PDE finite element method, and an innovative laboratory test was conducted to verify the numerical results. The effects of different factors (i.e., rainfall intensity, rainfall duration, saturated conductivity, and slope roughness coefficient) on water content and ponding depth with and without macropores were compared and analyzed. The results show that infiltration is more likely to happen in MF than UF (Unsaturated Flow, without macropore). The depths of the saturation zone and the wetting front of MF are obviously greater than those of UF. When SR occurs, rainfall duration has the most significant influence on infiltration. When macropores are considered, the ponding depth is smaller at the beginning of rainfall, while the effects are not obvious in the later period. Rain intensity and roughness coefficient have significant influences on the ponding depth. Therefore, macropores should not be ignored in the analysis of the slope seepage field.

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A 2D integrated FEM model for surface water–groundwater flow of slopes under rainfall condition

Cited by 20 publications

References 20 publications

A finite element model for simulating surface run‐off and unsaturated seepage flow in the shallow subsurface

A finite element model for simulating surface run‐off and unsaturated seepage flow in the shallow subsurface

Evaluation of failure of slopes with shaking-induced cracks in response to rainfall

Water Field Distribution Characteristics under Slope Runoff and Seepage Coupled Effect Based on the Finite Element Method

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