Numerical study on the influence of entrapped air bubbles on the time-dependent pore pressure distribution in soils due to external changes in water level

Ausweger, Georg Michael; Schweiger, Helmut

doi:10.1051/e3sconf/20160916010

Cited by 2 publications

(4 citation statements)

References 6 publications

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“…These analyses reveal, as expected, that the magnitude of these excess pore water pressures depends on the ratio between drawdown velocity and soil permeability and furthermore on the ratio between pore water compressibility and soil skeleton compressibility [3]. Also, the presence of air bubbles in the water may contribute to this effect [2]. In Fig.…”

Section: Problem Descriptionsupporting

confidence: 70%

Examples of successful numerical modelling of complex geotechnical problems

Schweiger

Fabris

Ausweger

et al. 2018

Innov. Infrastruct. Solut.

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Over the last decades, numerical methods have gained increasing importance in practical geotechnical engineering and numerical methods have become a standard tool in geotechnical design, widely accepted by the geotechnical profession. The advantages of numerical analyses for solving practical problems have been recognised, and developments in software and hardware allow their application in practice with reasonable effort. However, there is still a gap between practice and research and, often unnecessary, simplifications are made in practice and therefore the full power of numerical analyses is not always utilised. One reason for this discrepancy is a lack of transfer of knowledge from research into practice but also a lack of theoretical background of numerical methods, constitutive modelling and modern soil mechanics in practice. In this paper, the application of advanced numerical models for solving practical geotechnical problems is shown, whereas the examples have been chosen in such a way that different aspects are highlighted in each case. Results from fibre-optic measurements for a pull-out test of a ground anchor in soft soil could be reproduced by employing advanced constitutive models, in particular for the grout, in the bonded length of the anchor. For this test, a class-A prediction has been made and numerical results have then been compared with in situ measurements. The back-analysis of a slow-moving landslide is presented next, where the rate of deformation is influenced by water level changes in a reservoir for a pumping power plant, creep of lacustrine sediments and environmental effects such as rainfall infiltration. Finally, some results of modelling cone penetration testing in silts are presented highlighting the effects of anisotropic permeability.

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Section: Problem Descriptionsupporting

confidence: 70%

Examples of successful numerical modelling of complex geotechnical problems

Schweiger

Fabris

Ausweger

et al. 2018

Innov. Infrastruct. Solut.

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“…With growing size, such ganglia become more mobile [5] and may escape from the soil to the atmosphere. The pressure in the discontinuous air phase usually differs from the atmospheric pressure [6] and can be measured from the curvature of the water-air interface.…”

Section: Introductionmentioning

confidence: 99%

“…In this state, it contains a continuous air phase with connection to and in equilibrium with the atmosphere. Quasi-saturated [1] or satiated [7] soil contains air in the form of entrapped air bubbles or air ganglia with water pressures higher than the air entry value [6]. Fully saturated soil, which is rarely found under natural conditions, does not contain any air bubbles or ganglia.…”

Section: Introductionmentioning

confidence: 99%

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The Impact of Capillary Trapping of Air on Satiated Hydraulic Conductivity of Sands Interpreted by X-ray Microtomography

Princ

Fideles

Koestel

et al. 2020

Water

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The relationship between entrapped air content and the corresponding hydraulic conductivity was investigated experimentally for two coarse sands. Two packed samples of 5 cm height were prepared for each sand. Air entrapment was created by repeated infiltration and drainage cycles. The value of K was determined using repetitive falling-head infiltration experiments, which were evaluated using Darcy’s law. The entrapped air content was determined gravimetrically after each infiltration run. The amount and distribution of air bubbles were quantified by micro-computed X-ray tomography (CT) for selected runs. The obtained relationship between entrapped air content and satiated hydraulic conductivity agreed well with Faybishenko’s (1995) formula. CT imaging revealed that entrapped air contents and bubbles sizes were increasing with the height of the sample. It was found that the size of the air bubbles and clusters increased with each experimental cycle. The relationship between initial and residual gas saturation was successfully fitted with a linear model. The combination of X-ray computed tomography and infiltration experiments has a large potential to explore the effects of entrapped air on water flow.

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Numerical study on the influence of entrapped air bubbles on the time-dependent pore pressure distribution in soils due to external changes in water level

Cited by 2 publications

References 6 publications

Examples of successful numerical modelling of complex geotechnical problems

Examples of successful numerical modelling of complex geotechnical problems

The Impact of Capillary Trapping of Air on Satiated Hydraulic Conductivity of Sands Interpreted by X-ray Microtomography

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