Application of Advanced Procedures to Model Tests on the Subsoil Behavior Under Vertical Loading of Group Pile in Sand

摘要

It is known that bearing behavior of group pile is substantially different from the superposition of the singlepile loading in both clay and sandy grounds when the pile spacing is narrower. However the mechanism which causes the difference, called soil–pile–soil interaction, is less known in sand than in clay. This is because the sandy ground that bears the group pile has not been investigated well in previous studies. In order to obtain more direct information on the subsoil behavior, several advanced procedures including visualizing test and image analysis (PIV) and tactile sensors were adopted to discuss the behavior of the ground in this study. The clear difference of the ground deformation between wider and narrower spacing of piles in the group pile exists only before the bearing load yielded as revealed from visualizing test and PIV. It corresponded to the lower secant modulus of the tip resistance in narrower-spacing group pile at the same stage. After the ground yielding, the bearing behavior does not show significant difference among the piles. The bearing mechanism after yielding was investigated by PIV as well.