What Is the Darcy Seepage Flow Rate & Critical Exit Gradient Calculator?
Darcy seepage law models groundwater flow through porous soil media and determines the risk of internal erosion piping.
How Does the Darcy Seepage Flow Rate & Critical Exit Gradient Calculator Work?
Multiplies hydraulic conductivity by gradient and area for discharge; compares gradient to submerged soil unit weight.
Darcy Seepage Flow Rate & Critical Exit Gradient Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Q = k cdot rac{Delta h}{L} cdot A, quad i_{ ext{crit}} = rac{G_s - 1}{1 + e}, quad ext{FS} = rac{i_{ ext{crit}}}{i}
Darcy linear seepage law and Terzaghi critical hydraulic gradient for soil boiling.
How to Use the Darcy Seepage Flow Rate & Critical Exit Gradient Calculator
- Enter soil permeability k, differential head loss, flow path length, and cross-sectional area.
Step-by-Step Example Calculation
Earth Dam Foundation Seepage
Input Values:
permeabilityKCmS:0.005
headLossDeltaHMeters:3.5
flowPathLengthMeters:12
crossSectionAreaM2:8
Worked Steps: Discharge Q = 70.0 L/min with hydraulic gradient i = 0.292 and safety factor FS = 3.42 against piping.
Understanding Your Result
Shows discharge rate in L/min and calculates factor of safety against quicksand (FS > 3–4 required for dams).
Factors That Affect the Result
- Sheet pile cutoff walls and upstream clay blankets lengthen the flow path, decreasing the exit gradient.
When Should You Use This Calculator?
- Coffer dam excavation dewatering, earth embankment dam safety checks, and retaining wall weep hole sizing.
Assumptions & Limitations
- Assumes laminar flow complying with Darcy law; homogeneous isotropic soil.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard geotechnical groundwater seepage and piping model.