Now
we will see the basic equation provided by Terzaghi. Here the equation is given
for unit

*length.***foundation**
At
first we provide the parameter used in this expression:

Q=bearing
capacity of soil

B=foundation
width

C=cohesion
of soil

ϒ=unit
weight of soil

Df=depth
of foundation

As
an example:

Let
consider, c=200 lb/ft

^{2},
Φ=30

^{0}
B=5
ft

D

_{f}=3 ft
Q

_{static}=5(200X36 + 112X3X22 + 112X5X20)
=100960
lbs/ft of unit foundation length

If
earthquake hazard provides k=0.2 then

Q

_{earthqauke}=5(200X17 + 112X3X7 + 112X5X4)
=34360
lbs/ft of unit foundation length

From
this example we can conclude a considerable reduction in ultimate bearing
capacity of foundation soil is occurred on account of earthquake event.

**Earthquake Influence on Bearing Capacity of Foundation Soil (Part-1)**
I 'm surprised at the above eqn.

ReplyDeleteTerzagi Bearing Capacity eqn as given in Bowles book, Foundation Analysis & Design, states:

q ult = CNc.Sc + qNq +.5gamma.B.Ngamma.Sgamma

which is different than the quantity between brackets in the above eqn!

Pls note & advise.