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1

Particle shape effect on macroscopic behaviour of underground structures: numerical and experimental study

Szarf K., Combe G., Villard P.

Studia Geotechnica et Mechanica

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2014

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Vol. 36, nr 3

67--74

EN

The mechanical performance of underground flexible structures such as buried pipes or culverts made of plastics depend not only on the properties of the structure, but also on the material surrounding it. Flexible drains can deflect by 30% with the joints staying tight, or even invert. Large deformations of the structure are difficult to model in the framework of Finite Element Method, but straightforward in Discrete Element Methods. Moreover, Discrete Element approach is able to provide information about the grain–grain and grain–structure interactions at the microscale. This paper presents numerical and experimental investigations of flexible buried pipe behaviour with focus placed on load transfer above the buried structure. Numerical modeling was able to reproduce the experimental results. Load repartition was observed, being affected by a number of factors such as particle shape, pipe friction and pipe stiffness.

2

DEM numerical analysis of load transfers in granular soil layer

Chevalier B., Combe G., Villard P.

Studia Geotechnica et Mechanica

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2008

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Vol. 30, nr 1-2

147-163

EN

Load transfers and other arching effects are mechanisms frequently met in civil engineering, especially in areas subject to karstic subsidence or in geotechnical earth structures such as piled embankments. The study proposed focuses on the numerical discrete analysis of granular material response submitted to specific boundary conditions leading to load transfer (embankment built overa trench or over a network of piles). The influence of several parameters has been studied: granular layer thickness, friction behaviour and particle shapes. Various load transfer mechanisms are observed, depending on the boundaries and also on the granular layer properties. The comparison between three-dimensional Discrete Element Modelling and analytical calculation methods leads to a various agreement, depending on the case treated.

3

Wymiarowanie wzmocnień geosyntetycznych platform drogowych i kolejowych

Briancon L., Villard P.

Inżynieria Morska i Geotechnika

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2008

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nr 2

78-86

PL

Nowa metoda wymiarowania geosyntetyków nad powstałymi wgłębieniami platform drogowych i kolejowych uwzględniająca rozciąganie w strefach zakotwienia. Weryfikacja zaproponowanej metody badaniami w skali naturalnej. Nomogramy do wymiarowania wzmocnienia nasypu geosyntetykiem.

EN

New method for dimensioning of geosynthetics over cavities in road and railway platforms including extension of the material in anchoring zones. Verification of the method proposed by in situ tests. Dimensioning charts for geosynthetics reinforced embankments.

4

Modelling of a rock fall using the discrete element method and study of the seismic signal

Pater A., Dembicki E., Villard P.

Archives of Civil Engineering

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2008

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Vol. 54, nr 2

405-422

EN

The mechanism of big rock falls or avalanches is still poorly known, both for the rupture and propagation processes. The only quantitative data that are currently measured and available during a rock fall are the seismic signals recorded by seismological arrays. The signal properties (amplitude, duration, frequency) are obviously linked to the characteristics of the fall (mass, fall height, propagation distance) but no systematic study has been performed so far. This article aims at studying this relation by modeling the rock fall process. The used technique is the discrete element method (DEM) which allows to consider the different phenomena or parameters likely to influence the seismic signals: fracturing, rock fall type, morphology of the impact area.

PL

Mechanizm dużego spadającego bloku skalnego lub lawiny pozostaje nadal słabo rozpoznany zarówno w zakresie pęknięć jak i procesów propagacji. Jedynie ilościowe dane, które aktualnie są mierzone i uchwytne podczas spadania skały, zarejestrowane są jako sejsmiczne sygnały przez szereg sejsmografów. Właściwości sygnału (amplituda, trwanie, częstotliwość) są wyraźnie powiązane z cechami spadania (masa, wysokość spadania, odległość propagacji), lecz dotychczas nie były wykonane żadne systematyczne badania. Artykuł ma na celu badanie powyższej relacji za pomocą modelowania procesu spadającej skały. Do modelowania wykorzystano metodę elementów dyskretnych, która pozwala uwzględnić różne zjawiska bądź parametry mogące wpłynąć na sejsmiczny sygnał: pęknięcia, rodzaj spadającej skały, morfologię obszaru uderzenia.

5

Development of geodetect: a new warning system for the survey of reinforced earth constructions

Briancon L., Nancey A., Villard P.

Studia Geotechnica et Mechanica

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2005

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Vol. 27, nr 1-2

21-32

EN

Survey of civil engineering works and reinforced earth structures are more and more necessary either to detect the first sign of degradation before failure or to provide the designers and owners with some information on the behaviour of their buildings. In this context, the program "Geodetect" was launched to develop a warning system based on the optical technology applied in a geosynthetic. The results of the development lead to a reinforcing geosynthetic equipped with optical fibres, offering an accurate measuring system, available for very large areas, easy to install and completed with an analysis device and a warning system which may be adapted to the client's needs. This paper will present the different steps of the validation: tests in laboratory for fine tuning of the system, a full-scale experiment to show the resistance against the damage during installation and the behaviour above a cavity and a finite element modelling.