Unsaturated Hydraulic Conductivity of a Silty Sand with the Instantaneous Profile Method

Askarinejad, Amin; Beck, Alexander; Casini, Francesca; Springman, Sarah M.

doi:10.1007/978-3-642-31343-1_27

Cited by 9 publications

(4 citation statements)

References 6 publications

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“…The excellent agreement between the two curves indicates that it is feasible to use the one-D method for determining the unsaturated permeability coefficient of loamy sand. The instantaneous profile method is another widely-used approach for determining the unsaturated permeability coefficient of homogeneous or nonhomogeneous soils under the condition that soil moisture content is not affected by groundwater (Watson, 1966;Askarinejad et al, 2012), but it is time-consuming and error-prone because the dynamics of soil water suction and soil moisture content are normally hard to determine (Baker et al, 1974). By contrast, in the one-dimensional horizontal infiltration experiments, the needed parameters (including the cumulative horizontal infiltration, the wetting front distance and the infiltration time) can be readily determined and the experimental process is relatively easy and less time-consuming.…”

Section: Discussionmentioning

confidence: 99%

One-dimensional horizontal infiltration experiment for determining permeability coefficient of loamy sand

Zhu

Chen

2016

J. Arid Land

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A knowledge of soil permeability is essential to evaluate hydrologic characteristics of soil, such as water storage and water movement, and soil permeability coefficient is an important parameter that reflects soil permeability. In order to confirm the acceptability of the one-dimensional horizontal infiltration method (one-D method) for simultaneously determining both the saturated and unsaturated permeability coefficients of loamy sand, we first measured the cumulative infiltration and the wetting front distance under various infiltration heads through a series of one-dimensional horizontal infiltration experiments, and then analyzed the relationships of the cumulative horizontal infiltration with the wetting front distance and the square root of infiltration time. We finally compared the permeability results from Gardner model based on the one-D method with the results from other two commonly-used methods (i.e., constant head method and van Genuchten model) to evaluate the acceptability and applicability of the one-D method. The results showed that there was a robust linear relationship between the cumulative horizontal infiltration and the wetting front distance, suggesting that it is more appropriate to take the soil moisture content after infiltration in the entire wetted zone as the average soil moisture content than as the saturated soil moisture content. The results also showed that there was a robust linear relationship between the cumulative horizontal infiltration and the square root of infiltration time, suggesting that the Philip infiltration formula can better reflect the characteristics of cumulative horizontal infiltration under different infiltration heads. The following two facts indicate that it is feasible to use the one-D method for simultaneously determining the saturated and unsaturated permeability coefficients of loamy sand. First, the saturated permeability coefficient (prescribed in the Gardner model) of loamy sand obtained from the one-D method well agreed with the value obtained from the constant head method. Second, the relationship of unsaturated permeability coefficient with soil water suction for loamy sand calculated using Gardner model based on the one-D method was nearly identical with the same relationship calculated using van Genuchten model.

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Section: Discussionmentioning

confidence: 99%

One-dimensional horizontal infiltration experiment for determining permeability coefficient of loamy sand

Zhu

Chen

2016

J. Arid Land

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“…The saturated permeability was set to k sat =1.0•10 −5 m/s, which is one order of magnitude higher with respect to the value measured in the laboratory (10 −6 m/s) by Askarinejad et al (2012a). It also lies within the range of values determined from in situ permeability measurements, which suggest values ranging from 10 −4 m/s to 10 −5 m/s (Askarinejad 2013;…”

Section: Numerical Model Descriptionmentioning

confidence: 95%

Hydro-mechanical analysis of a surficial landslide triggered by artificial rainfall: the Ruedlingen field experiment

et al. 2021

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This paper interprets the hydromechanical behaviour of a steep forested instrumented slope during an artificial rainfall event, which triggered a shallow slope failure fifteen hours after rainfall initiation. The soil"s mechanical response has been simulated by coupled hydro-mechanical finite element analyses, using a critical state constitutive model that has been extended to unsaturated conditions. Failure occurs within a colluvium shallow soil cover, characterised as a silty sand of low plasticity. The hydraulic and mechanical parameters are calibrated, based on an extended set of experimental results, ranging from water retention curve measurements to triaxial stress path tests under both saturated and unsaturated conditions. Rainfall is simulated as a water flux at the soil surface and suitable boundary conditions account for the hydromechanical interaction between the soil cover and the underlying bedrock. The results are compared with field data of the mechanistic and the hydraulic responses up to failure and are found to provide a very satisfactory prediction. The study identifies water exfiltration from bedrock fissures as the main triggering agent, resulting in increased pore pressures along the soil-bedrock interface, reduced available shear strength and cause extensive plastic straining, leading to the formation and propagation of a failure surface.

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“…The values of these parameters are assumed based on experimental investigations performed by Askarinejad et al [21], Askarinejad [22] and Casini et al [23], on silty sand. Furthermore, the value of the initial preconsolidation pressure, based on the past loading history, is set to 15 kPa, to assure the initial stability of the considered model slope.…”

Section: Numerical Examplesmentioning

confidence: 99%

Strength Reduction Method in the Stability Assessment of Vegetated Slopes

Świtała

2023

Architecture, Civil Engineering, Environment

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The thoughtful design and mitigation of ecological slope stabilization measures rely heavily on the reliable assessment of the stability of vegetated slopes. This is a complex problem due to the many aspects of vegetation presence that must be taken into account. The numerical model should be able to consider mechanical root reinforcement and root water uptake, which can lead to soil desaturation. This paper presents the application of the strength reduction method to the Modified Cam-Clay model for unsaturated, root-reinforced soils, which allows for the quantitative estimation of slope stability. The technique is implemented in finite element software and tested using several numerical examples. Firstly, the sensitivity of the factor of safety to changes in root constitutive parameters is investigated. In the second example, the stability of the modelled slope is assessed under rainfall of a certain duration followed by progressively modifying soil strength parameters until failure occurs. Furthermore, slope stability is assessed for various durations of the rainfall period.

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Unsaturated Hydraulic Conductivity of a Silty Sand with the Instantaneous Profile Method

Cited by 9 publications

References 6 publications

One-dimensional horizontal infiltration experiment for determining permeability coefficient of loamy sand

One-dimensional horizontal infiltration experiment for determining permeability coefficient of loamy sand

Hydro-mechanical analysis of a surficial landslide triggered by artificial rainfall: the Ruedlingen field experiment

Strength Reduction Method in the Stability Assessment of Vegetated Slopes

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