Test: Darcy’s Law - Civil Engineering (CE) MCQ

The flow of water through soils may be either a laminar flow or turbulent flow

The pore size in gravel is larger, hence the gravels are highly permeable than sand which is least permeable.

In 1856, Darcy studied the law of flow of water through soil and demonstrated experimentally the laminar flow conditions.

According to Darcy’s law, the rate of flow or discharge per unit area is proportional to the hydraulic gradient .
q α i
q = K i A, where K =Darcy’s coefficient of permeability
A = total cross-sectional area.

 As the dimension of the coefficient of permeability k are same as those of velocity. It is expressed in terms of cm/sec or m/day or feet/day.

For fine sand, the coefficient of permeability is 0.05 to 0.001 cm /sec or
5×10-2 to 1×10-3.

Darcy’s la of linear dependency between the velocity of flow and hydraulic agent is valid for only laminar flow conditions in the soil.

 In 1933, Lewis and Barnes demonstrated experimentally that Darcy’s law is valid if it is ≤ 1.

As stiff clay does not contain any porous materials, it may be termed as least permeable or impermeable.