Study of flood embankment behaviour induced by air entrapment

Leśniewska, Danuta; Zaradny, H.; Bogacz, P.; Kaczmarek, J.

doi:10.1201/9780203883020.ch75

Cited by 6 publications

(6 citation statements)

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“…The typical water air viscosity ratio is about 50 to 60, while for a perfect agreement of the two-phase model with the Richards equation a ratio of about 100 or more is required (Tegnander 2001, Szymkiewicz 2013. Other sources of discrepancies seem to be the lack of connectivity between the pore air and the atmosphere, which may lead to air pressure buildup ahead of the infiltration front during ponded infiltration (e.g., Vachaud et al 1973) or to formation of regions of trapped pore air (e.g., Leśniewska et al 2009). …”

Section: Two-phase Flow Model and Richards Equationmentioning

confidence: 99%

Influence of heterogeneous air entry pressure on large scale unsaturated flow in porous media

2014

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A b s t r a c tThe paper presents numerical simulations of water infiltration in unsaturated porous media containing coarse-textured inclusions embedded in fine-textured background material. The calculations are performed using the two-phase model for water and air flow and a simplified model known as the Richards equation. It is shown that the Richards equation cannot correctly describe flow in the presence of heterogeneities. However, its performance can be improved by introducing appropriately defined effective capillary and permeability functions, representing largescale behaviour of the heterogeneous medium.

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Section: Two-phase Flow Model and Richards Equationmentioning

confidence: 99%

Influence of heterogeneous air entry pressure on large scale unsaturated flow in porous media

2014

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“…In 2006, this test rig was modernised by adding a system of sensors to measure the pressure of air and water in soil pores. In 2011 other changes were introduced, facilitating the acquisition of a more complete record and digital analysis [2,8,9].…”

Section: Methodsmentioning

confidence: 99%

Degradation of flood embankments – Results of observation of the destruction mechanism and comparison with a numerical model

Bogacz

2017

Open Engineering

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Abstract:The paper presents the results of model tests conducted for a flood embankment under varying conditions of saturation. Test embankments were formed from the natural sea sand. The test apparatus consisted of the box with internal dimensions 200 × 100 × 4.5 cm , and thus ensured the implementation of the plane strain state. In most tests during watering air entrapment was observed, leading to formation of open soil discontinuities, called macropores (their dimensions many times exceeded the grain size of the soil skeleton). Analysis of images from a number of tests allowed to create a simplified model of the evolution of a macropore. The numerical model has been based on the finite element method using the PLAXIS 2D software. A comparison has been made between the observation of the phenomena occurring in the physical model and the results of the simulation of the phenomena in the numerical model. A correlation has been proven between the results acquired in reality and the results derived from the numerical model.

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“…In order to investigate this phenomenon, a series of experiments were carried out in the Institute of Hydro-Engineering of the Polish Academy of Sciences in Gdańsk. They included infiltration in closed columns [58][59][60] and infiltration and overflowing on a model sand slope [1,5,24], and on a model sand dike [4,23,24]. Overflowing experiments on various model structures in 2D flumes showed formation of air pockets and subsequent damage of the structure, which was attributed to the increase of air pressure.…”

Section: Introductionmentioning

confidence: 99%

“…Pressure change in unsaturated area: 1, before overtopping; 2, just after overtopping; 3, state corresponding to the max. value of pressure in the area; 4 and 5, decreasing of the air pressure caused by the increasing volume of the macropore[23][24][25] …”

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Simulations of air and water flow in a model dike during overflow experiments

et al. 2018

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Flow in flood dikes, earth dams, and embankments occurs in variably saturated conditions, with pores of the earth material filled partly with water and partly with air. In routine engineering analysis, the influence of pore air is neglected and the air pressure is assumed equal to atmospheric. In some circumstances, for example, during overtopping of the dike by water, the effect of pore air on water flow and stability of the structure can be important. These features cannot be captured with the commonly used Richards equation. In this paper, we analyze earlier experiments on the overtopping of a model dike made of fine sand. During the experiments, a significant amount of air was trapped near the outer slope of the dike, which later escaped through a fracture formed in wet sand. The observations were compared with numerical simulations using the Richards equation and the two-phase immiscible flow model. The deformation and damage of the dike were not modelled, but the initial evolution of the entrapped air pressure (before damage occurred) was in a good agreement with two-phase flow simulations.

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Study of flood embankment behaviour induced by air entrapment

Cited by 6 publications

References 1 publication

Influence of heterogeneous air entry pressure on large scale unsaturated flow in porous media

Influence of heterogeneous air entry pressure on large scale unsaturated flow in porous media

Degradation of flood embankments – Results of observation of the destruction mechanism and comparison with a numerical model

Simulations of air and water flow in a model dike during overflow experiments

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