posted on 2009-03-24, 13:22authored byNeil Dixon, M.P. Spriggs
In soil slopes, developing shear surfaces generate acoustic emission (AE). The
Authors have previously proposed the use of active waveguides for monitoring the
stability of such slopes. Active waveguides comprise of a steel tube installed in a preformed
borehole through a slope with coarse grained soil backfill placed in the
annulus around the tube. Deformation of the host soil generates AE in the active
waveguide. Field trials of this system reported previously have shown that AE rates
are linked to slope deformation rates. This paper extends the study by detailing a
method for quantifying slope movement rates using an active waveguide. A series of
laboratory experiments are presented and used to define the relationship between AE
event count rate and displacement rate. The method was shown to differentiate rates
within an order of magnitude, which is consistent with standard landslide movement
classification (i.e. 1 to 0.001 mm per minute), using a relationship derived between
the gradient of the event count rate with time and deformation rate. In addition, it was
possible to detect a change in displacement rate within two minutes of it occurring
even at very slow rates (i.e. 0.0018mm/min). Knowledge of changes in displacement
rate is important in situations where slope movements are suddenly triggered or
displacements accelerate in response to a destabilising event. Field trials of a realtime
AE monitoring system are currently in progress to compare performance against
traditional instrumentation.
History
School
Architecture, Building and Civil Engineering
Citation
DIXON, N. and SPRIGGS, M.P., 2007. Quantification of slope displacement rates using acoustic emission monitoring. Canadian Geotechnical Journal, 44 (8), pp. 966-976.