Group pile is the foundation that supports a footing with several
piles. The behavior of a group pile is totally different from that
of a single pile if the pile spacing becomes narrow enough
because of the pile-soil-pile interaction. To investigate the
effects of the interaction in the group pile, model tests were
conducted by previous researchers [Whitaker (1957), Vesic
(1967), and Itoh and Yamagata (1998)]. However, the bearing
mechanism of the group pile is not so clear yet as that of a
single pile. As a result, it is not yet understood clearly whether
or not the bearing capacity of the group pile is greater or less
than that of a single pile
To understand the bearing mechanism of a group pile, the
interaction should be studied more scientifically. It is thus
necessary to observe precisely the behavior of piles and the
surrounding ground in detail during group pile loading.
Additionally, a large-scale model is also required to make clear
the effects of interaction in a group pile.
Therefore, loading tests on a group pile and a single pile were
conducted in a large soil tank with several sensors; strain gauges
in the piles, colored sand layers and tactile sensors. To
investigate the effect of pile spacing on the interaction, two
kinds of models with different spacing were tested. A single pile
with a large diameter was also tested for comparison based on
the comparison between the group piles and the single pile, the
bearing mechanism of group pile was discussed.