Flow Net
Flow net represents the flow of water through a soil graphically. Applications include calculation of uplift pressure, exit gradient, heaving and pore water pressure.
What is flow net?
Flow net represents the flow of water through a soil graphically. In field, under sheet piles, under dams and under masonry structures flow is not 1D, it may be 2D/3D
What are the assumptions to be made?
• Soil mass is fully saturated and Darcy’s law is valid.
• Soil is homogeneous and isotropic.
• Soil grains and water are incompressible
Laplace equation
Laplace equation describes how the energy head is dissipated as the flow takes place through soil. The general solution gives two set of curves perpendicular to each other, flow lines and equipotential lines.
• Flow takes place in between the flow lines.
• Equipotential lines are the point of equal head
Seepage through soils from Flownet is shown below.
What are the applications of Flow net?
• Calculation of uplift pressure
• Exit gradient/Piping
• Heaving
• Pore Water pressure
What are the methods of construction of Flow net?
• Analytical methods
• Electrical analogy method
• Capillary flow model
• Sand model
• Graphical method