earth pressure at rest

EARTH PRESSURE AT REST
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https://youtu.be/PgE8rmNZX5A

1. TOPIC
EARTH PRESSURE AT REST
SUBJECT :-FOUNDATION ENGI NEERING
PREPARED
BY
ER. SANJEEV SINGH
[email protected]
PART II

2. EARTH PRESSURE AT REST
The expressions for earth pressure at rest would be used to for
the determination of the magnitude and line of action of the
total forces due to earth pressure on the retaining structure.
Fig show a retaining wall in which no movement take place.
The vertical effective stress at point A at a depth Z is given by
The horizontal effective stress can be obtained using the
coefficient of earth pressure at rest {Ko}, which is equal to the
ratio of the horizontal stress to the vertical stress.
Thus

3. EARTH PRESSURE AT REST
The stress x is usually represented as Po, indicating the lateral pressure at rest.
Thus
It may be noted that the coefficient of lateral pressure at rest {Ko} relates the effective stresses.
Thus total lateral pressure {ph} is equal to the sum of the intergranular pressure{po} and the
pore water pressure {u}.
Thus
In fig the lateral pressure at depth Z is therefore.
As above equation indicates, the pressure distribution is triangle with zero pressure at the
top{z=0} an the maximum pressure at bottom of the wall.

4. EARTH PRESSURE AT REST
As fig (a) show the pressure distribution when the soil
is dry.
The pressure at the bottom of the wall at depth H is
given by
The total pressure force per unit length of the wall is
given by

5. EARTH PRESSURE AT REST
Infig(b),thedepthofwatertableisatdepthdbelowthe
surface.Thepressureatdepthz>disgivenby
Thepressureatthebottom(Z=H)ofthewallisgivenby

6. EARTH PRESSURE AT REST
If the water table is at the ground surface fig (c), the
pressure at the bottom is taken d=0 in equation
above
The resultant pressure p acting on the wall is
determined from the pressure distribution diagram