This study deals with identifying the behavior of contiguous pile groups subjected
to vertical load and the corresponding soil failure. A wide range of geometrical
parameters were represented in order to study the effect of these parameters on the
behavior of pile group including spacing between piles and diameter of piles (D) in
the group. To study the effect of diameter, the piles used in the laboratory tests were
3 and 5 cm in diameter and 35cm in length. D to 2D spacing between piles were
also adopted. The sand used in the experimental program had two different
densities. The tests were executed in a wide tank containing the sand as well as
models of pile groups. Using the experimental model results, relations between load
and settlement were utilized to estimate the bearing capacity of the pile group. From
the test results, it was found that increasing the spacing between piles and diameter
of piles in a group causes increase of the bearing capacity of the pile group.
However, decreasing the pile spacing reduced the load capacity of the pile group.