Influence of Air Entrappment on Flood Embankment Failure Mechanism - Model Tests

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

doi:10.2478/v10022-008-0015-y

Cited by 4 publications

(6 citation statements)

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“…In articles [8,9] showed that entrapped or escaping air cause cracking near the surface which results in a damage of the structure. Cracks appear between the entrapped air areas and outer boundaries.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, most of the available software for modeling unsaturated zone flow is based on the Richards equation, which does not account for the air flow. However, there is an increasing evidence that in some situations air flow must be taken into account: heterogeneous soils [1][2][3], rapid downward infiltration [4], water table fluctuations [5], seismic events [6] or overtopping of dikes [7][8][9][10]. In such cases the two phase flow model should be taken into account.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the air phase on water flow in dikes

Tisler

Szymkiewicz

2017

E3S Web Conf.

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Abstract. Numerical models are often used to describe flow and deformation processes occurring in dikes during flood events. Modeling of such phenomena is a challenging task, due to the complexity of the system, consisting of three material phases: soil skeleton, pore water and pore air. Additional difficulties are transient loading caused by variable in time water levels, heterogeneity of the soil or air trapping. This paper presents a brief review of the influence of the air phase in soil on water flow and pore pressure generation, with focus on applications related to stability of dikes, earth dams and similar structures. Numerical simulations are carried out to investigate the differences between the Richards equation and the two-phase flow model, using an in-house code based on the finite volume method. A variety of boundary problems are considered, including seepage through flood dikes, dike overtopping and water level fluctuations. Special attention is paid to the problem of air trapping, which occurs when water flows over the top of a dike. Such a phenomenon occurred during experiments on model dikes reported in the literature, ultimately leading to development of cracks and damages in dike structure.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of the air phase on water flow in dikes

Tisler

Szymkiewicz

2017

E3S Web Conf.

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“…The initial observation results were described earlier [2,4,6]. In most tests, during saturation of the flood embankment model, a phenomenon was observed involving the entrapment of air in areas which remained dry for a cer-tain time period, in spite of being surrounded from the outside by saturated soil.…”

Section: Results Of the Observation Of The Physical Modelmentioning

confidence: 74%

“…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%

“…The programme of the modelling studies, involved three methods of saturating the model, all of them simulating intense rain -landward slope, water flowing over the top of the flood embankment, as well as a change in the water level from the riverward slope side [2]. The boundary condition for the F10 and F14 tests (type 1) -ground water level was set at h = 10cm from the bottom of the model.…”

Section: Methodsmentioning

confidence: 99%

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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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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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Influence of Air Entrappment on Flood Embankment Failure Mechanism - Model Tests

Cited by 4 publications

References 0 publications

Influence of the air phase on water flow in dikes

Influence of the air phase on water flow in dikes

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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