Quantification of the influence of preferential flow on slope stability using a numerical modeling approach

Shao, Wei; Bogaard, Thom; Bakker, Mark; Greco, Roberto

doi:10.5194/hessd-11-13055-2014

Cited by 3 publications

(8 citation statements)

References 89 publications

(127 reference statements)

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“…Assuming a unique, nonhysteretic relationship between water content and capillary pressure, water can flow through the water-filled saturated smaller pores with higher capillary pressure, while the larger pores will remain empty and inactivated for conducting unsaturated flow [58].…”

Section: Theorymentioning

confidence: 99%

“…The effects of pore water velocity distribution on soil hydrology can be visualized by a perturbation analysis with a hypothetical infiltration experiment. Considering soil under unit hydraulic gradient condition as ∂ h − z /∂z = −1 (when h is constant), the specific discharge is equal to the hydraulic conductivity (q = K) [58]. Under this condition, an increment of water flow on the surface boundary will cause downward pressure propagation.…”

Section: Expressing Pore Water Velocity Distribution By a Celeritymentioning

confidence: 99%

“…Assuming that the fluid dynamics are independent among tubes, the celerity under variably saturated condition express the one-to-one correspondence between the maximum pore water velocities with the water content [58]. When exerting the perturbation analysis in saturated/unsaturated soil, the celerity as a first-order derivative of the hydraulic conductivity function can quantify the pore hydraulic conductivity distribution (equivalent to the pore water velocity distribution) under unit hydraulic gradient condition.…”

Section: Expressing Pore Water Velocity Distribution By a Celeritymentioning

confidence: 99%

“…Considering a one-dimensional and uniform flow under the unit hydraulic gradient condition, the transport of conservative tracer in a subsurface flow system can be described with the pore bundle model, and the breakthrough curve can be derived from velocity distribution [58]. If the water content is constant and equal to θ w , M of the N tube groups are filled with water, so that the water content θ w may be written as …”

Section: Derivation Of a Breakthrough Curve Through The Celeritymentioning

confidence: 99%

“…In this study, the numerical approach was used to derive the breakthrough curve of the unmodified and modified Mualem-van Genuchten models. We hereafter demonstrate an example of deriving the breakthrough curve C t c of a nonreactive tracer from the celerity function based on the Brooks-Corey model, to be more explicitly linking the tracer transport with the pore water velocity distribution [58].…”

Section: Geofluidsmentioning

confidence: 99%

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Quantify the Pore Water Velocity Distribution by a Celerity Function

Shao

Yang

et al. 2018

Geofluids

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Celerity and velocity of subsurface flow in soil porous medium are intimately linked with tracer transport, while only few current studies focused on their relations. This study conducted theoretical analyses based on a pore bundle model, under which celerity in unsaturated flow is equivalent to maximum velocity. Furthermore, under 3 models Brooks-Corey model and unmodified and modified Mualem-van Genuchten models, we used a celerity function to derive breakthrough curves aiming to quantify the advective tracer transport for 5 typical soil textures. The results showed that the celerity under near-saturated conditions can be 5 up to 100 times larger than the saturated hydraulic conductivity, and a small volumetric fraction (<15%) of pores contributed more than half of the specific discharge. First arrival time and extensive tailing of the breakthrough curves were controlled by maximum velocity and velocity distribution, accordingly. As the kinematic ratio in the Brooks-Corey model remained constantly for each specific soil, we used it to quantify the ratio of maximum tracer velocity over average tracer velocity. We also found that a bimodal soil hydraulic function (for a dual-permeability model) may result in similar soil hydraulic conductivity functions for different parameter sets, but their celerities are different. The results showed that the proposed celerity function can assist in investigating subsurface flow and tracer transport, and the kinematic ratio could be used to predict the first arrival time of a conservative tracer.

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Section: Theorymentioning

confidence: 99%

Section: Expressing Pore Water Velocity Distribution By a Celeritymentioning

confidence: 99%

Section: Expressing Pore Water Velocity Distribution By a Celeritymentioning

confidence: 99%

Section: Derivation Of a Breakthrough Curve Through The Celeritymentioning

confidence: 99%

Section: Geofluidsmentioning

confidence: 99%

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Quantify the Pore Water Velocity Distribution by a Celerity Function

Shao

Yang

et al. 2018

Geofluids

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Soil water dynamics under different forest vegetation cover: Implications for hillslope stability

Hayati

Abdi

Saravi

et al. 2018

Earth Surf Processes Landf

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Though it is well known that vegetation affects the water balance of soils through canopy interception and evapotranspiration, its hydrological contribution to soil hydrology and stability is yet to be fully quantified. To improve understanding of this hydrological process, soil water dynamics have been monitored at three adjacent hillslopes with different vegetation covers (deciduous tree cover, coniferous tree cover, and grass cover), for nine months from December 2014 to September 2015. The monitored soil moisture values were translated into soil matric suction (SMS) values to facilitate the analysis of hillslope stability. Our observations showed significant seasonal variations in SMS for each vegetation cover condition. However, a significant difference between different vegetation covers was only evident during the winter season where the mean SMS under coniferous tree cover (83.6 kPa) was significantly greater than that under grass cover (41 kPa). The hydrological reinforcing contribution due to matric suction was highest for the hillslope with coniferous tree cover, while the hillslope with deciduous tree cover was second and the hillslope with grass cover was third. The greatest contributions for all cover types were during the summer season. During the winter season, the wettest period of the monitoring study, the additional hydrological reinforcing contributions provided by the deciduous tree cover (1.5 to 6.5 kPa) or the grass cover (0.9 to 5.4 kPa) were insufficient to avoid potential slope failure conditions. However, the additional hydrological reinforcing contribution from the coniferous tree cover (5.8 to 10.4 kPa) was sufficient to provide potentially stable hillslope conditions during the winter season. Our study clearly suggests that during the winter season the hydrological effects from both deciduous tree and grass covers are insufficient to promote slope stability, while the hydrological reinforcing effects from the coniferous tree cover are sufficient even during the winter season.

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Effect of collapse-type lateral pressure induced by irrigation

Xia

Zhu

2023

Preprint

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Loess collapse-type lateral pressure may have a landslide-promoting effect in loess slope areas. However, research on the magnitude and characteristics of collapse-type lateral pressure and its impact on slope stability remains blank. A study on the variability of loess collapse-type lateral pressure in the Heifangtai area and its sliding mechanism has been analyzed. Collapse tests and numerical simulations by FLAC3D of loess were conducted according to local safety field theory. The results indicate that Heifangtai loess is self-weighted collapsible loess; soil of the irrigated area at depths of 0-15 m are slightly collapsible; soil at depths of 20-25 m are moderately collapsible loess, and the loess in the unirrigated area regardless of depth is highly collapsible. As the depth or moisture content increases, the lateral pressure gradually increases, correspondingly the deformation becomes greater. In saturated state, the maximum lateral pressure reaches 123 kPa when collapsible deformation occurs, the collapse-type lateral pressure coefficient increases of up to 1.4 times, and horizontal deformation is also correspondingly large. As the water content of the slope increases from 4% to 20%, the total slope displacement increases from 12 mm to 140 mm and covers a large part of the slope, the lateral pressure coefficient also gradually increases, and the range of increase gradually expands; the slope safety coefficient also decreases, the area of failure becomes gradually wider until the slope toe is penetrated; the shear fractures move gradually toward the slope toe, and shear failure occurs at the 1/3 of the slope toe in the collapse deformation process. Collapse action leads to tensile stresses in the upper part of the slope, making it prone to collapse-type crack formation, resulting in dominant channels of surface water infiltration and forming landslide scarps. What’s more, collapse action also enables the formation of compressive stresses in the lower part of the slope, resulting in outward extrusion of deep soil, increased sliding force, and landslide formation.

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Quantification of the influence of preferential flow on slope stability using a numerical modeling approach

Cited by 3 publications

References 89 publications

Quantify the Pore Water Velocity Distribution by a Celerity Function

Quantify the Pore Water Velocity Distribution by a Celerity Function

Soil water dynamics under different forest vegetation cover: Implications for hillslope stability

Effect of collapse-type lateral pressure induced by irrigation

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