# SOIL MECHANICS AND FOUNDATION ENGINEERING-I (CE-210) • Lecture-7

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Lecture-7
SOIL MECHANICS
AND FOUNDATION ENGINEERING-I (CE-210)
PERMEABILITY
Definition: Permeability is defined as the property of porous
material which permits the passage or seepage of water (or other
fluids) through its interconnecting voids.
Factors Affecting Permeability
•
Grain Size
•
Property of the pore fluid
•
Void ratio of the soil
•
Structural arrangement of the soil particles
•
Entrapped air and foreign matter
•
PERMEABILITY DETERMINATION IN THE LAB
• 𝑘=
𝑉𝐿
𝐴 𝑡 Δ𝐻
•
k = Coefficient of permeability
•
V = Quantity of water collected
•
t = time in which water is collected
•
L = length of sample
•
A = area of cross section
•
PERMEABILITY DETERMINATION IN THE LAB
• 𝑘=
𝑎𝐿
𝐻𝑜
2.3 𝑙𝑜𝑔10
𝐴𝑡
𝐻1
•
k = Coefficient of permeability
•
a = area of cross section of tube
•
L = length of sample
•
A = area of cross section
•
•
•
t = time elapsed to come water head from H 0 to H1
PROBLEMS
1. Calculate the coefficient of permeability of a soil sample, 6cm in
height and 50 cm2 in cross sectional area, if a quantity of water
equal to 430ml passed down in 10 minutes, under an effective