GEOTECHNICAL

ENGINEERING

ECG 503

LECTURE NOTE 04

LEARNING OUTCOMES

Learning outcomes:

At the end of this lecture/week the students would

be able to:

Draw flow nets below concrete dams and

through earth dams.

Use the flow nets to determine quantity of

seepage flow.

The equation proposed by

Kozeny (1927) relates

permeability to particle sizes,

porosity (n), angularity of

particles, spesific surface, S and

viscosity of water.

• An excessive hydraulic gradient in the

ground, for instance near to the

downstream toe of an earth dam can cause

local instability leading to gradual erosion

and the formation of well defined channels

or pipes beneath the structures.

• This effect is known as piping and the

progressive sub surface erosion of soil can

rapidly lead to a diastrous failure.