Physical Properties of Soil

Phase Diagram of Soil
Soil is composed of solids, liquids, and gases. Liquids and gases are mostly water and air, respectively. These two (water and air) are called voids which occupy between soil particles. The figure shown below is an idealized soil drawn into phases of solids, water, and air.



Weight-Volume Relationship from the Phase Diagram of Soil
total volume = volume of soilds + volume of voids
$V = V_s + V_v$

volume of voids = volume of water + volume of air
$V_v = V_w + V_a$

total weight = weight of solids + weight of water
$W = W_s + W_w$

Three Reservoirs Connected by Pipes at a Common Junction

Three reservoirs A, B, and C are connected respectively with pipes 1, 2, and 3 joining at a common junction P. Reservoir A is at elevation 80 m, reservoir B at elevation 70 m and reservoir C is at elevation 60 m. The properties of each pipe are as follows:

Pipe 1:   L = 5000 m, D = 300 mm
Pipe 2:   L = 4000 m, D = 250 mm
Pipe 3:   L = 3500 m

The flow from reservoir A to junction P is 0.045 m3/s and f for all pipes is 0.018.



  1. Find the elevation of the energy grade line at P in m.
    A.   75.512
    B.   73.805
    C.   72.021
    D.   74.173
  2. Determine the flow on pipe 2 in m3/s.
    A.   0.025
    B.   0.031
    C.   0.029
    D.   0.036
  3. Compute the diameter appropriate for pipe 3 in mm.
    A.   175
    B.   170
    C.   178
    D.   172

Problem 20 - Bernoulli's Energy Theorem

Problem 20
The 600-mm pipe shown in Figure 4-11 conducts water from reservoir A to a pressure turbine, which discharges through another 600-mm pipe into tailrace B. The loss of head from A to 1 is 5 times the velocity head in the pipe and the loss of head from 2 to B is 0.2 times the velocity head in the pipe. If the discharge is 700 L/s, what power is being given up by the water to the turbine and what are the pressure heads at 1 and 2?



Problem 19 - Bernoulli's Energy Theorem

Problem 19
A pump draws water from reservoir A and lifts it to reservoir B as shown in Figure 4-10. The loss of head from A to 1 is 3 times the velocity head in the 150-mm pipe and the loss of head from 2 to B is 20 times the velocity head in the 100-mm pipe. Compute the horsepower output of the pump and the pressure heads at 1 and 2 when the discharge is: (a) 12 L/s; (b) 36 L/s.



Problem 17 - Bernoulli's Energy Theorem

Problem 17
In Figure 4-08 is shown a siphon discharging water from reservoir A into the air at B. Distance 'a' is 1.8 m, 'b' is 6 m, and the diameter is 150 mm throughout. If there is a frictional loss of 1.5 m between A and the summit, and 1.5 m between the summit and B, what is the absolute pressure at the summit in kiloPascal? Also determine the rate of discharge in cubic meter per second and in gallons per minute.



Problem 16 - Bernoulli's Energy Theorem

Problem 16
A pump (Figure 4-07) takes water from a 200-mm suction pipe and delivers it to a 150-mm discharge pipe in which the velocity is 3.6 m/s. The pressure is -35 kPa at A in the suction pipe. The 150-mm pipe discharges horizontally into air at C. To what height h above B can the water be raised if B is 1.8 m above A and 20 hp is delivered to the pump? Assume that the pump operates at 70 percent efficiency and that the frictional loss in the pipe between A and C is 3 m.



Problem 15 - Bernoulli's Energy Theorem

Problem 15
A pump (Figure 4-07) takes water from a 200-mm suction pipe and delivers it to a 150-mm discharge pipe in which the velocity is 2.5 m/s. At A in the suction pipe, the pressure is -40 kPa. At B in the discharge pipe, which is 2.5 m above A, the pressure is 410 kPa. What horsepower would have to be applied by the pump if there were no frictional losses?



Problem 14 - Bernoulli's Energy Theorem

Problem 14
Water discharges through an orifice in the side of a large tank shown in Figure 4-06. The orifice is circular in cross section and 50 mm in diameter. The jet is the same diameter as the orifice. The liquid is water, and the surface elevation is maintained at a height h of 3.8 m above the center of the jet. Compute the discharge: (a) neglecting loss of head; (b) considering the loss of head to be 10 percent of h.



Problem 13 - Bernoulli's Energy Theorem

Problem 13
The 150-mm pipe line shown in Figure 4-05 conducts water from the reservoir and discharge at a lower elevation through a nozzle which has a discharge diameter of 50 mm. The water surface in the reservoir 1 is at elevation 30 m, the pipe intake 2 and 3 at elevation 25 m and the nozzle 4 and 5 at elevation 0. The head losses are: from 1 to 2, 0; from 2 to 3, 0.6 m; from 3 to 4, 9 m; from 4 to 5, 3 m. Compute the discharge and make a table showing elevation head, pressure head, and total head at each of the five points.