Permeability and Flow of Water in Soils - Elements of Soil Mechanics - page 72

Exercise 2.4
A cylinder of cross-sectional area 2500 mm 2 is filled with sand of permeability
5.0 mm/s. Water is caused to flow through sand under a constant head using the
arrangement shown in Fig. 2.33.
Determine the quantity of water discharged in 10 min.
Answer 9 × 10 6 mm 3
Fig. 2.33 Exercise 2.4.
Exercise 2.5
The specific gravity of particles of a sand is 2.54 and their porosity is 45% in the
loose state and 37% in the dense state. What are the critical hydraulic gradients for
these two states?
Answer 0.85, 0.97
Exercise 2.6
A large open excavation was made into a stratum of clay with a saturated unit weight
of 17.6 kN/m 3 . When the depth of the excavation reached 7.63 m the bottom rose,
gradually cracked, and was flooded from below with a mixture of sand and water;
subsequent borings showed that the clay was underlain by a bed of sand with its
surface at a depth of 11.3 m.
Compute the elevation to which water would have risen from the sand into a drill
hole before excavation was started.
Answer 6.45 m above top of sand
Exercise 2.7
A soil deposit consists of three horizontal layers of soil: an upper stratum A (1 m
thick), a middle stratum B (2 m thick) and a lower stratum C (3 m thick). Permeability
tests gave the following values:
Soil A 3 × 10 − 1 mm/s
Soil B 2 × 10 − 1 mm/s
Soil C 1 × 10 − 1 mm/s