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Modélisation 3D par imagerie LIDAR et analyse structurale de la Salle du Dôme des Grottes de Han-sur-Lesse (Belgique, Ardenne)

par Kazmierczak, Elise ;Jaillet, Stéphane;Vandycke, Sara ;Verheyden, Sophie
Référence Géomorphologie, 26, 4, page (231-246)
Publication Publié, 2021-08-01

Article révisé par les pairs

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Résumé :

The “Salle du Dôme”, located in the middle of the karstic network of the Han-sur-Lesse Cave, is the biggest known cavity in terms of underground volume in Belgium. A large fold thrust can be seen across its roof. In February 2016 a high resolution 3D model of the “Salle du Dôme” was generated, using lasergrammetry acquisition (terrestrial LIDAR). This model resulted in a complete visual representation of the cavity. LIDAR images are very useful to perform structural quantitative analysis of the fractures and discontinuities of rocks in a karstic cavity, because the cave walls are usually difficult to access. The analysis of the fractures of the “Salle du Dôme” was then integrated into the regional tectonic history. Thanks to the reverse engineering software 3DReshaper©, it became possible to create a geometrical viewing of the fold thrust by a succession of planes created with at least three points on the stratification planes. The direction and dip of each plane are determined with trigonometric calculations, based on the coordinates of their normals, which are available thanks to the viewer software. On the basis of the 3D model, it is possible to present a structural pattern of the roof. Finally, the structural analysis based on LIDAR images helps to better understand the geometry and dynamics of a regional structure which plays an undeniable role in the evolution of the karstogenesis of the cavity.