5 Four flow nets are drawn under the same piles and impervio

5. Four flow nets are drawn under the same piles and impervious blanket on the next page. Answer the followings. (a). calculate the permeability of the soil, k-1.0x 102 cm/sec. q(A)- cross section of dams with different location of the sheet amount of flow rate q for all cases. hi 10 meter, and the coefficient of q(B)- q(C)- q(D)- (b). calculate the water pressures at A, B. C, and D. Use the following table to complete the calculations. Elevation Pressure Head (m) Head (m) Water Pressure (kN/m2) Point Total Head (m) 25 25 25 25 (c). What is an advantage of dam B over dam A? (d). What are two advantages of dam D over dam C?

Solution

k= 10^-2cm/s so in metres, = 10^-4 m/s

q (A) = k *H* N_f/N_d = 1* 10^-4 *10* 5/15 = 3.33* 10^-4 m²/s

q (B) = 1* 10^-4* 10*5/15 = 3.33* 10^-4 m²/s

q (C) = 1* 10^-4* 10*5/9 = 5.55* 10^-4 m²/s

q (D) = 1* 10^-4* 10*5/20 = 2.5* 10^-4 m²/s

Points Total Head (m) Elevation head (m) Pressure head (m) Water Pressure(KN/m²)

A 35 25 10 98.1 = h* density*g

B 35 25 10 98.1

C 35 25 10 98.1

D 35 25 10 98.1

C) Advantage of Dam B over Dam A is that it has a better distribution of flow nets ,

D) Dam D has better flow net network

and a uniform potential drop pattern.