This study is concerned 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 investigate the effect of these
parameters on the behavior of the pile group including spacing between piles and
number of piles in group. To study the effect of length, the piles used in laboratory
tests were 3 cm in diameter and 30 cm in length. D to 2D spacing between piles
were also adopted. The sand used in the experimental program had two different
densities. The scope of research includes tests on vertical loaded contiguous pile
groups in sand. The tests were executed in a wide tank containing the sand as well
as models of pile groups. Using the experimental model results, relations 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 number of piles in a group < br />causes increase of the bearing capacity of the pile group.