Method to compute pressure distribution in leaky layers

[dbrakenhoff]

Thanks for bringing this up, @HendrikMe. It is important to point out that the leaky layers don't need to be divided into several layers to simulate the correct effect, as vertical flow in the leaky layers is already simulated analytically. See, for example, the theory explained here: https://github.com/mbakker7/ttim/blob/master/papers/2013_bakker_ttim_theory.pdf (you need to download the pdf, as github doesn't show it in most browswers).

For dike stability, it is important to compute the pressure change in the leaky layer. Although ttim simulates this, there is no function to compute the pressure distribution inside a leaky layer at the moment. This would be an important additional function to be added for the computation of dike stability. Maybe you can add an Issue for an Enhancement?

Originally posted by @mbakker7 in #99 (reply in thread)

[HMEUW]

Thanks for creating a specific issue for this subject.

First I post some snippets from Dutch literature. To make sure we discuss the same.

An example calculation is given in Figuur b4.2 (Technisch Rapport Waterspanningen bij Dijken).

A section with the indringingslengte is given in Figuur b1.5 (Technisch Rapport Waterspanningen bij Dijken).

@dbrakenhoff I understand from your post that transient 'indringing' is simulated by ttim, but you cannot compute/visualize this at the moment.

There for the Issue for Enhancement is to include the vertical transient groundwater flow in a leaky aquifer in ttim. The result should be like the two included figures in this post.

[MattBrst]

To add to @HMEUW's comments: Figure b4.3 (Technisch Rapport Waterspanningen bij Dijken) contains the missing link between the figures:

I understand from @dbrakenhoff's comments that it is theoretically possible to calculate a continuous pressure distribution within a leaky layer, but not yet implemented in TTim. The simplification to break down the continuous pressure distribution into a part which 'feels' the change (the 'indringingslengte') and a part which does not feel the change, is done for the geotechnical postprocessing with discrete soil layers with discrete hydraulic heads at the top and bottom of the soil layers.