Precursory signs of a large cavern collapse
Résumé
In France, besides the room-and-pillar method, solution mining has also been carried out largely, creating numerous abandoned cavities, presently collapsed or not. Nowadays, controlled collapse of the huge cavities created by intensive solution mining has been introduced as a full part of the exploitation scheme, avoiding then a projected permanent hazard. Then, opportunity to monitor early warning signs, precursory events and ground collapse mechanisms was seized through a relevant research operation in 2005. This consisted in the field monitoring experiment of the controlled collapse of an approximately 1.5 million cubic meters solution mined cavern lying between 190 and 280 meters deep. The experiment resulted in the recording of a considerable scientific dataset, including tens of thousands microseismic events along with numerous strain, displacement and pressure time series.