Transparent Acrylic Constant-Head Permeameter Cell
Machined cylindrical chamber (75.0 mm ID, 250 mm height) with top and bottom porous stones.
Civil Engineering / Constant Head Permeability
FREE TO EXPLORELABORATORY 21 · CIVIL ENGINEERING
Constant-Head Hydraulic Conductivity (Permeability) of Granular Soils by Darcy's Law
Determine the hydraulic conductivity (coefficient of permeability, k) of coarse-grained cohesionless granular soils under steady-state laminar seepage using the constant-head permeameter according to ASTM D2434 / AASHTO T215. Explore interactive structural mechanics, materials simulation, and civil engineering telemetry.
STRUCTURAL MATERIALS · MECHANICS · GEOTECHNICAL · HYDRAULICS · HIGHWAYS · SURVEYING
Your virtual civil engineering laboratory.
DISCHARGE FLOW RATE Q—
CIVIL INFRASTRUCTURE TELEMETRY
Ready to sample with Head Diff Δh = 30.0 cm.
Adjust Head Diff Δh, then execute civil engineering measurement.
Civil engineering telemetry is evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity structural mechanics and geotechnical continuum modeling.
Civil engineering assumptions and boundary condition limits
The civil engineering physical models apply within the specified calibrated operational window (10.0 to 60.0 cm). Medium uniform sand specimen: cell inside diameter D = 7.50 cm (area A = π · 7.5^2 / 4 = 44.1786 cm^2), manometer tapping spacing L = 15.0 cm. Calibrated hydraulic conductivity k = 0.4923 cm/s. Flow sensitivity slope Q / Δh = k A / L = 0.4923 · 44.1786 / 15.0 = 1.4500 cm^2/s.
Laboratory apparatus & testing equipment.
Multi-Tube Piezometer Manometer Board
Vertical glass manometer tubes spaced along the cell measuring piezometric head to 1 mm resolution.
Adjustable Constant-Head Water Supply Tank
Wall-mounted overflow tank maintaining constant inlet head without pressure fluctuation.
De-Aired Water Circulation Supply System
Vacuum de-airing tank supplying dissolved-gas-free water to prevent air bubble clogging.
Graduated Measuring Glass Cylinder & Digital Stopwatch
Measures effluent outflow volume V (up to 1000 mL) over timed intervals to 0.1 s.
Digital Water Thermometer
Monitors permeant fluid temperature to 0.1 °C for dynamic viscosity temperature corrections.
FOLLOW THE METHOD
A reason behind every step.
Determine the hydraulic conductivity (coefficient of permeability, k) of coarse-grained cohesionless granular soils under steady-state laminar seepage using the constant-head permeameter according to ASTM D2434 / AASHTO T215. Standardized parameter settings: 10.0, 20.0, 30.0, 40.0, 50.0, 60.0 cm.
01
Permeameter Cell Assembly & Sand Placement
Place lower porous stone into permeameter cell; pour oven-dried clean sand in uniform layers using a funnel; tamp gently to target density; seat upper porous stone; record specimen length L and area A.
02
De-Aired Water Saturation & Bubble Purging
Connect bottom inflow port to de-aired water supply; allow water to percolate upward slowly under low head to displace all entrapped pore air; purge manometer lines.
03
Constant-Head Reservoir Elevation
Adjust overhead water tank height to establish initial hydraulic head difference Δh = 10.0 cm between manometer ports; allow steady seepage to establish for 5 minutes.
04
Volumetric Flow Rate Measurement
Place dry graduated cylinder under the effluent outlet; start stopwatch simultaneously; collect outflow for 60 seconds; record collected volume V (cm³); calculate Q = V / t.
05
Head Differential Sweep
Increase reservoir elevation to establish head differentials of 20.0, 30.0, 40.0, 50.0, and 60.0 cm; record steady discharge flow rate Q at each plateau.
06
Temperature Correction & Permeability Calculation
Measure effluent water temperature T; plot Q versus Δh; evaluate slope to compute hydraulic conductivity k_T and standardize to 20 °C (k_20).
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into civil engineering insight.
Points are your recorded observations. The solid regression line validates Constant Head Permeability mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
Q = 1.4500 · Δh
| # | Hydraulic Head Difference Δh (cm) | Discharge Flow Rate Q (cm³/s) | Piezometric head difference Δh (cm) | Discharge flow rate Q (cm³/s) | Remove |
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CHECK YOUR UNDERSTANDING
Explain what the civil engineering metrics mean.
Darcy's Law for fluid flow through soil is expressed mathematically as:
The hydraulic gradient i is defined as:
According to Hazen's formula, hydraulic conductivity of clean sand scales approximately with:
The constant-head permeability test is suitable primarily for which type of soil?
THEORY AND STRUCTURAL CONTEXT
Civil engineering background & physical principles.
Hydraulic conductivity (permeability, k) is the primary geotechnical transport property governing groundwater seepage beneath earth dams, dewatering rates for deep foundation excavations, drainage through highway base courses, and consolidation settlement kinetics in saturated soil deposits. Formulated empirically by Henry Darcy in 1856 through public water fountain filtration experiments in Dijon, France, Darcy's law states that the apparent discharge velocity v of fluid through a porous medium is directly proportional to the hydraulic gradient i: v = k · i, where i = Δh / L (head loss per unit seepage length). The volumetric discharge rate Q through soil of cross-sectional area A is Q = k · i · A = k · (Δh / L) · A. Under ASTM D2434, the constant-head permeameter test is specifically designed for coarse-grained permeable soils (hydraulic conductivity k > 10^-4 cm/s, such as sands and gravels). A cylindrical soil specimen is held in a transparent permeameter cell connected to an adjustable constant-head reservoir with an overflow weir that maintains an invariant hydraulic head difference Δh. Manometer piezometer ports tapped along the specimen length monitor internal head loss across a known spacing L. In this laboratory, discharge flow rate Q is measured across head differentials from 10 to 60 cm to verify Darcy's linear seepage law and determine hydraulic conductivity k.
Q = 1.4500 · Δh
Medium uniform sand specimen: cell inside diameter D = 7.50 cm (area A = π · 7.5^2 / 4 = 44.1786 cm^2), manometer tapping spacing L = 15.0 cm. Calibrated hydraulic conductivity k = 0.4923 cm/s. Flow sensitivity slope Q / Δh = k A / L = 0.4923 · 44.1786 / 15.0 = 1.4500 cm^2/s.