Page 59 - Unit2.docx
P. 59
Figure 6-2 Block failure
In general ,the bearing capacity of pile group may be calculated in consideration
to block failure in a similar way to that of single pile, by means of equation 4-2,but
hear A as the block surface area and A as the base area of the block or by
b
s
rewriting the general equation we get:
© It's Engg. Life
................................(6.2)
where:
As, surface area of block
Ab = base area of block (see fig.6-3)
Cb, Cs= average cohesion of clay around the group and beneath the group.
Nc = bearing capacity factor. For depths relevant for piles, the appropriate value
of Nc is 9
Wp and Ws = weight of pile respective weight of soil
In examining the behaviour of pile groups it is necessary to consider the
following elements:
• a free-standing group, in which the pile cap is not in contact with the
underlying soil.
• a "piled foundation," in which the pile cap is in contact with the underlying soil.
