Geotechnical Data and Pile Design - Offshore Structures: Design, Construction and Maintenance - page 274

Ram compression-
only spring
represents cushion
drive cap

M Mass

M

K c

Linear spring

M

K f

Compression-only
spring

M

K f

Damper

M

K f Linear spring with

maximum force
limited by friction

M

K f/p

M

K p Frictional

limit to
maximum
spring
force
dynamic

r = Ram
f

M

Follow
p = Pile

=

K p

M

K p

Approximate
dynamic soil
model

M

FIGURE 4.12 Dynamic analysis model of pile driving.

such as the location of the maximum stresses down the length of the pile, the
number of blows, previous experience with the pile-hammer combination and
the confidence level in the analyses. In most cases, special considerations
apply to avoid damage to the appurtenances when there are significant driving
stresses may be transmitted into the structure.
The static stress during driving may be taken to be the stress resulting from
the weight of the pile above the point of calculation plus the pile-hammer com-
ponents actually supported by the pile during the hammer blows, including any
bending stresses resulting therefrom. It is the responsibility of the contractor to
control the hydraulic hammers so that the driving energy does not exceed the
rated energy, because usually only a limited deviation is considered in the engi-
neering study. It is important to calculate carefully the static stresses present
due to the hydraulic hammers, because there are possible variations in driving
configurations, for example, in installing and driving the piles without lateral