The management of underground cavity indices is variable and dependent on several criteria including:
The typology of the underground cavity index
Depending on whether it is punctual (example of a localized collapse) or surface (example of a declaration of opening of marl on a so-called “Napoleonic” plot), visible or not, depending on whether it impacts buildings or not, and depending on the project owner (individual, municipality, etc.), ALISE offers you the most suitable solution and manages all the players.
The project owner
Depending on the project owner (individual, municipality, etc.), ALISE analyzes the issues and offers to manage all the parties concerned. We organize public and information meetings during which we propose technical solutions specific to each case. We help with the formation of associations of local residents affected by the same problem, as well as with the search for subsidies.
The means implemented (documentary studies, stripping, drilling, etc.)
DOCUMENTARY STUDIES
Drawing on its 10 years of experience, ALISE carries out documentary research in order to verify the data, position and mapping of indices that could impact buildings; To do this, ALISE carries out research in departmental archives and produces alignment plans based on the Napoleonic cadastre.
STRIPPING
Stripping is a so-called “destructive” method that can be used occasionally concerning a terrain index, a backfilled area, or large areas and to a depth of 0.7m.
The use of a mechanical excavator with a smooth bucket makes it possible to find traces of old filled marl pits and to locate collapses...
DESTRUCTIVE DRILLING
Destructive drilling with parameter recording makes it possible to validate the presence or absence of underground void and decompressed terrain. They are necessary when stripping is not possible or has not revealed conclusive elements. They are carried out around an index or in a portcullis, generally, in order to redefine a new security perimeter.
THE CREATION OF WELLS
When the indicator is proven or strongly suspected “underground mining”, it may be more economical to create a new access shaft to the marl. ALISE enlists the services of a specialist and offers to recreate a “chimney” in order to have access to the farm. This physical presence within the gallery(s) makes it possible to know the general state of the operation, to cube it and to redefine a security perimeter adjusted to the work.