What is flow network in soil mechanics

With a Flow network - also called potential network or potential network - one graphically depicts a seepage flow in the ground with streamlines and potential lines in two dimensions. Flow lines and potential lines, which can both be curved, always intersect at right angles to each other. The network, also known as the streamline network or potential line network, consists of small, right-angled, curvilinearly-edged square-like meshes that can gradually change their size. A decreasing mesh size indicates an increase in the seepage speed.

In the flow network, the potential lines connect the points with the same potential, i.e. in this case the same standpipe level. The streamlines represent the direction of the flow, the stream filaments. The amount of water flowing through is the same in each stream filament. The potential lines are equally spaced from one another as long as the permeability is the same. If the permeability is lower, the distance between the potential lines becomes smaller and vice versa. The potential lines not only intersect the flow lines at right angles, they are also perpendicular to impermeable edges.

A flow network is used to calculate the seepage flow through a dam, a dike, along an embankment or under a weir, through an excavation or the groundwater flow to a well. The result is the amount of water that seeps through, the pore water pressures, the standpipe level heights at various points, and from this the bottom water pressure can be calculated. The hydraulic gradient is the potential difference between two potential lines based on their distance. It must not become too large in the seeped soil, as otherwise the slope could break or other structural damage could occur. The gradient can be reduced by lengthening the seepage path and thus increasing the distance between the potential lines.

It takes some skill to draw a flow network. However, the potentials can also be calculated quite well with the finite element method. The calculation is based on potential theory, Darcy's law and Laplace’s differential equation. The potential lines and the gradients can also be calculated and displayed well. The determination of streamlines is a much bigger computational problem.

The construction of flow networks goes back to Philipp Forchheimer.

literature

• Henner Turk: Statics in earthworks. 3. Edition. 1999, ISBN 978-3-433-01791-3
• Hans-Jürgen Lang, Jochen Huder, Peter Amann: The flow network. In: Soil mechanics and foundation engineering
• The flow network.

Categories:Hydrogeology | Fluid Mechanics | Soil mechanics

Status of information: 11/22/2020 2:03:55 AM CET

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