Numerical simulation of active heat injection near an earth-concrete dam interface for the identification of anomalous seepage
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Date
2013
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University of New Brunswick
Abstract
Active heat injection and temperature monitoring are methods that may be useful
for the detection of anomalous seepage in embankment dams. The main objectives of this
research were to investigate, using numerical simulation, the feasibility of using active
heat injection and distributed temperature monitoring to identify anomalous seepage at
the interface between earth embankments and concrete structures, and to quantify
seepage rates for a hypothetical zone of enhanced permeability at the clay core-concrete
interface. A three-dimensional finite element model was developed to simulate the
injection of heat into a vertical borehole drilled within concrete with an orientation
parallel to the clay core-concrete interface. Anomalous seepage at the interface was
created by increasing the permeability in a 3 m thick zone and imposing a range of
hydraulic gradients. For a borehole-interface separation distance of 1.5 m, the maximum
temperature deviations within the heat injection borehole, due to the anomalous seepage,
are less than 0.6°C. For borehole-interface separation distances of 1.0 m and 0.5 m, the
simulations reveal deviations in the range of l.0-5.1°C during the heat injection phase,
and less than l .2°C during the cooling phase. The temperature deviations are simulated to
be less than l.0°C at a temperature monitoring borehole located 1.0 m down gradient of
the heat injection location for the borehole-interface separation distances of 1.5 m and 1.0
m. These findings suggest that the heat injection and monitoring boreholes would need to
be located less than 1.0 m from the interface to ensure maximum temperature deviations
of l .0°C or greater. Provided the heat injection location is within 1.0 m of the interface, it
is concluded that interpretation of temperature data collected prior, during, and following
heat injection should enable the identification of anomalous seepage zones.