Acoustic Emission Evaluation of an Arch Dam during Construction Cooling and Grouting
Acoustic emission (AE)
monitoring was conducted in order to ensure safe construction of an arch dam
under severe climate conditions. The AE was detected during the secondary
cooling in the winter time while the construction was suspended due to low
temperature and heavy snow. In the spring time just before the construction
restarted, AE was monitored during grouting into a joint of dam blocks. A
multi-channel digital signal processing system (MISTRAS) was used to perform a
quantitative AE waveform analysis based on the moment tensor analysis as well
as the conventional AE parameter measurement. Low frequency PAC R1.5I AE
sensors (15 kHz resonant) were employed to detect AE signals since the signals
with ordinary frequencies attenuate greatly during the propagation in concrete
of the dam. Twelve sensors were buried from the dam surface and four were
mounted on the corridor floor inside the dam. Neither critical AE activity nor
intense AE cluster was observed in the AE monitoring. Thus, it was confirmed
that the dam was safe during both the secondary cooling and the grouting. The
AE monitoring was proven to be very useful for the safety inspection of a dam
under construction in severe conditions.
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Above: Development view and photograph of an arch dam under construction |
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Left: Sensor placement on the concrete surface (A): An AE sensor and the drilled
concrete surface |
Copyright 2003, Nippon Physical Acoustics, LTD., All rights reserved
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