Page 320 - Numerical Analysis and Modelling in Geomechanics

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Figure 10.6 Comparison of axial load distribution to individual piles in 5×5 pile group.

Table 10.4 Parameters for the linear analyses reported in Figures 10.6–10.7

Lateral load distribution
As a pile group is subjected to a lateral load, this will result in a lateral
deformation as well as a rotation of the group and hence the piles at the edge will
be loaded axially in tension and compression. Thus, only if rotation of the cap is
prevented, do the piles deflect purely horizontally and hence the lateral load
deformation characteristics of the group can be analysed separately from the axial
ones. For such fixed-head pile groups, the lateral load distribution to the
individual piles predicted by selected numerical codes is examined by applying a
lateral load of 15 MN to the same group of piles analysed in the previous
section, and under the same soil conditions (refer to Tables 10.4 and 10.5).
Similarly, Figure 10.7 shows the lateral load distribution (where H is the load
is the average load acting on each pile
acting on the individual pile head and H av
head) as a function of the normalised pile spacing (s/d).
In the linear range, the PGROUPN solutions compare favourably with
DEFPIG, while significant discrepancies with the MPILE analysis are observed
in the corner load prediction. These differences may partially be explained with
the approximations involved in the interaction factor approach which ignores the
stiffening effects of piles within the soil mass, thereby leading to an
overestimation of group interaction, as discussed in Section 3. Consideration of