D.13 MONITORING MOVEMENTS UNDER THE HALL

From the start, the hall in this building has been the area in the galleries most visited by both the public and scientists and researchers. This made it a priority to continuously monitor any movements in order to assess and control this sector’s overall stability. The first movement monitoring equipment we installed here, therefore, was strain gauge 1, with two devices for measuring horizontal displacements.

The gilt cylinder on the wall is the head of this equipment for measuring linear movements. This device, like the other two deployed in what are considered to be the building’s most sensitive areas, measures differences in tenths of a millimetre between an outside point and one or more anchoring points inside. To install them, we drilled a horizontal borehole, in this case to a length of nine metres, in which we installed anchoring fixtures at five and nine metres. Any movements between these points are automatically recorded, with a measuring accuracy of tenths of a millimetre.

The readings taken so far have revealed, for example, slight seasonal movements linked to the entry of water during periods of heavy rainfall.