Numerical modeling of the soil structure interaction during sinkholes

Matthieu Caudron (1, 2) , Fabrice Emeriault (2) , Richard Kastner (2) , Marwan Al Heib (1)

1 INERIS - Institut National de l'Environnement Industriel et des Risques
2 LGCIE - Laboratoire de Génie Civil et d'Ingénierie Environnementale

Sinkholes are the results of underground cavities failure. Due to the fact that those cavities can be natural (for example caused by the dissolution of rocks by underground water flow ) or man-made (such as mines and quarries), large areas are concerned. The consequences of sinkholes on building and on population are generally dramatic. Therefore, it is necessary to determine the effects of any possible sinkhole on existing and new building or public area. Even though it is obvious that the overall stiffness and weight of the structure influences the size and shape of the soil movement profiles, the main features of this soil-structure interaction phenomenon are not well established. Therefore, the common practice consists in evaluating the soil movements in “greenfield” conditions and then designing a structure capable of withstanding these movements. This approach can lead either to over-estimate or under-estimate the actions applied to the structure. Different cases of study will allow us to highlight the main phenomenon and so to propose different solutions to protect the population and the building from this risk. The aim of this article is to shed some light on this complex soil-structure interaction using a numerical approach. In a first step, a small-scale physic model was developed using cohesive Schneebeli material. Now we are using a discrete element approach with PFC2D software from Itasca. However some limitations imposed by PFC2D such as extensive time of computation due to the great number of particules, lead us to look out for a coupled FLAC2D-PFC2D model. This will allow us to represent the soil far of the cavity by a continuum and the soil near the cavity by an assembly of discrete elements. This reduce dramatically the time needed to compute the model and so allow us to perform more different study with variable parameters. The model will present two layer of soil. The first one, on the top of the cavity, will have a weak cohesion and a low thickness. The second one will be a powder soil on which a structure representing a real building could be placed. The soil response will be observed during the formation of a sinkhole in greenfield versus the tests with a building over it. Different parameters will be used : such as the thickness of the two layers, the dimensions of the cavity and the position of the structure over the cavity.

Mots clés: interaction sol-structure; fontis; effondrement; discrete element modelling

Domaines: Mécanique [physics.med-ph]

Matthieu Caudron, Fabrice Emeriault, Richard Kastner, Marwan Al Heib. Numerical modeling of the soil structure interaction during sinkholes. Numerical methods in geotechnical engineering, 2006, Graz, Austria. pp.267-273. ⟨ineris-00145208⟩