What is the equivalent coefficient of permeability in the direction of flow for the given arrangement of different soil layers?
(where K1, K2 & K3 are the coefficient of permeability of soil layers of thickness H1, H2 & H3 and L = length of soil layers as shown in figure and )
1
(K1 + K2 + K3)
2
\(\frac{H}{{\frac{{{H_1}}}{{{K_1}}} + \frac{{{H_2}}}{{{K_2}}} + \frac{{{H_3}}}{{{K_3}}}}}\)
3
[(K1 + K2 + K3) x (H1 + H2 + H3)]
4
\(\frac{{{K_1}{H_1} + {K_2}{H_2} + {K_3}{H_3}}}{H_1+H_2+H_3}\)