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Hydroacoustic monitoring of a salt cavity: an analysis of precursory events of the collapse

Abstract : One of the main features of 'post mining' research relates to available methods for monitoring mine-degradation processes that could directly threaten surface infrastructures. In this respect GISOS, a French scientific interest group is investigating techniques for monitoring the eventual collapse of underground cavities. One of methods under investigation was monitoring the stability of a salt cavity through recording microseismic-precursor signals that may indicate the onset of rock failure. The data were recorded in a salt mine in Lorraine (France) when monitoring the controlled collapse of 2,000,000 m3 of rocks surrounding a cavity at 130 m depth. The monitoring in the 30 Hz to 3 kHz frequency range highlights the occurrence of events with high energy during periods of macroscopic movement, once the layers had ruptured; they appear to be the consequence of the post-rupture rock movements related to the intense deformation of the cavity roof. Moreover the analysis shows the presence of some interesting precursory signals before the cavity collapsed. They occur a few hours before the failure phases, when the rocks were being weakened and damaged. They come from the damaging and breaking process, when micro-cracks appear and then coalesce. From these results we expect that deeper signal analysis and statistical analysis on the complete event time distribution (several millions of files) will allow us to finalize a complete typology of each signal families and their relations with the evolution steps of the cavity over the five years monitoring.
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Contributor : François Lebert Connect in order to contact the contributor
Submitted on : Wednesday, January 25, 2012 - 1:58:32 PM
Last modification on : Monday, October 11, 2021 - 1:02:06 PM
Long-term archiving on: : Monday, November 19, 2012 - 2:45:09 PM

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François Lebert, Séverine Bernardie, Guénolé Mainsant. Hydroacoustic monitoring of a salt cavity: an analysis of precursory events of the collapse. Natural Hazards and Earth System Sciences, Copernicus Publ. / European Geosciences Union, 2011, 11 (9), pp.2663-2675. ⟨10.5194/nhess-11-2663-2011⟩. ⟨hal-00662871⟩

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