How does automatic mesh refinement benefit the calculation of
pore-water pressures in a reservoir draw-down scenario? The
following example identifies errors which may occur using a fixed
One particularly interesting class of seepage modeling problems is the calculation of pore-water pressures in earth dams next to reservoirs. The function of the earth dam is primarily to dissipate the energy of the head created by the reservoir water level. However, a number of additional design and operational issues may be examined with a seepage model. These design issues include:
1. Calculations of head loss.
2. Calculation of maximum exit gradient.
3. Pore-water pressure build up due to rapid draw-down.
In this article we wish to concentrate on the third application:
pore-water pressure build-up due to rapid draw-down.
In this scenario a numerical model is set up to evaluate the initial
pore-water pressures of an earth dam experiencing rapid
draw-down of the reservoir. Excessive pore-water pressures in the
earth dam in this scenario can lead to upstream slope failures.
It is commendable that the practicing geotechnical consultant has
become aware of the need to apply numerical models to this type
of problem. The correct calculation of pore-ware pressures in this particular application can
lead to significant numerical challenges as shown in the following
In this case let’s take the example of a typical earth dam.
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