Question

Calculate the coefficient of permeability of a soil sample 6 cm in height and 50cm2in cross sectional area, if a quantity of water equal to 500 ml passed down in 15 minutes under an effective constant head of 40cm.

Answer 1

Answer:

Q=430

L=6

t=10

h=40

k=ql/thA

=430×6/10×60×40×50

=2.15×10 rased power_3 cm/s

Answer 2

Given:

• Length = 6 cm
• Area of cross-section = 50 $cm^2$
• Quantity of water = 500 ml
• Time taken to flow = 15 mins = 15 × 60 secs = 900 secs
• Constant Head = 40 cm

To find:

• The value of the coefficient of permeability.

Solution:

The formula to find the coefficient of permeability is given by,

⇒ q = k×i×A

q = Q/t and i = (H/L) on substituting for "q" and "i" in the above equation we get,

⇒ Q/t = k(H/L)A

rearranging the above equation in terms of "k" we get,

⇒k = (Q×L)/(A×t×H)  → {equation 1}

Where "k" is the coefficient of permeability, "H" is the head constant, "A" is the area of cross-section, "L" is the length, "t" is the time taken to flow, and "Q" is the quantity of water.

On substituting the given values in equation 1 we get,

⇒ k = (500×6)/(50×900×40) {multiplying the terms}

⇒ k = 3000/18000 {dividing the terms}

⇒ k = 0.0016 = 1.6 × $10^{-3}$ cm/sec or 1.6 × $10^{-5}$ m/sec.

∴ The value of the coefficient of permeability = 1.6 × $10^{-5}$ m/sec or 1.6 × $10^{-3}$ cm/sec .