1. SHREE LABHUBHAI TRIVEDI INSTITUTE OF ENGINEERING AND TECHNOLOGY
GEOTECHNICS & APPLIED GEOLOGY
SUBMITTED TO :
Mr. SANDEEP CHANDANI
SUBMITTED BY :
VARASANI RASIK ( )
VEGAD PRITESH ( )
VIRADIYA PRASHANT ( )

2. CONSTANT HEAD PERMEABILITY TEST
Object :
To determine the coefficient of permeability of a soil specimen by constant head method.
Equipments :
Permeability mould, internal diameter =100 mm, effective height = mm, capacity=1000 ml, complete with all accessories.
Constant head tank.
Graduated cylinder, stop water, thermo meter.
Filter paper, vacuum pump.
Weighing balance, 0.1 gm accuracy.

4. Test procedure :
Measure internal dimensions of the mould. Apply a little grease on the inside to the mould.
Take about 2.5 kg of the soil, from a thoroughly mixed wet soil, in the mould. Compact the soil at the required dry density using suitable compacting device.
Remove the collar and base plate. Trim the excess soil level with the top of the mould.
Clean the outside of the mould. Find the mass of the soil in the mould. Take a small specimen of the soil in a container for the water constant determination.
Saturate the porous stones.
Place the porous stones on the drainage base and keep a filter paper on the porous stone .

5. Place a filter paper and a porous stone on the top of specimen.
7. Place the mould with soil on the drainage base.
Place a filter paper and a porous stone on the top of specimen.
Connect the constant head tank to the drainage cap inlet.
Open the stop cock, and allow the water to flow downward so that all the air is removed, then close the stop cock.
Now, again open the stop cock and at the same time start the stopwatch. Collect the water flowing out the base in a measuring flask for some convenient time interval.
Measure the difference of head (h) in levels between the constant head tank and the outlet in the base.

6. Coefficient of permeability (k), k = (Q × L)/(t × h × A) cm/sec
c/s area of specimen = A = π/4 × D² (cm²)
Volume of mould = V = π/4 × D² × L (cm³)
Mass of wet soil in the mould = M = M₂ - M₁
where, M₁ = mass of empty mould
M₂ = mass of mould + wet soil.
so,
bulk density of soil, ƍb= M/V gm/cm³.
dry density of soil, ƍd = ƍb /(1+w) gm/cm³.
Coefficient of permeability (k),
k = (Q × L)/(t × h × A) cm/sec

7. Quantity of water collected (Q) ml
Observation Table :
Sr. No.
Quantity of water collected (Q) ml
Duration (t)
second
Constant head (h) cm
i = h/l
k = (Q/t) × (1/ i A) 1. 2. 3.

8. FALLING HEAD PERMEABILITY TEST
Object:
To determine the coefficient of permeability of a soil specimen by falling head method.
Equipments:
All the equipments required for the constant head permeability test.

10. Test Procedure:
Prepare the remoulded soil specimen in the permeameter and saturate it.
Keep the permeameter mould in the bottom tank and fill the bottom tank with water up to its outlet.
Connect the water inlet nozzle of the mould to the stand pipe filled with water . Permit water to flow for some time till steady state of flow is reached.
Now open the valve of stand pipe and record time to fall the head from h1 to h2. Repeat this step atleast twice.

11. Coefficient of permeability(k):
k=6 × [(a × L) / (A × t)] × log10 (h1/h2)
Where,
a = c/s area of stand pipe (cm²)
A = c/s area of soil sample = (π/4) × D² (cm²)
L = length of soil sample (cm)
t = time interval to fall head from h1 to h2
h1= initial head (cm)
h2= final head (cm)

12. Q=60 cm³ k = (Q×L) /(t×h×A)
Example :
a soil sample is tested for permeability and following observation are noted.
Hydraulic head = 22 cm
Length of specimen = 10 cm
diameter of sample = 4 cm
quantity of water collected = 60 cc
Time taken = 15 min
Determine coefficient of permeability.
Solution :
Q=60 cm³ k = (Q×L) /(t×h×A)
t = 15 min = 900 sec = (60×10)/(900×22×12.56)
L = 10 cm = 2.412×10-3 cm/sec
h = 22 cm
d=4 cm
A=(π/4)×(4)² = cm²

13. THANK YOU