Experimental Study of Mechanical Behavior of Passive Loaded Piles Adjacent to Piled Foundation

Abstract

For combined piled foundation, passive loaded piles will be subjected to horizontal force when piled foundation is loaded, and horizontal force may cause the piles horizontal displacement, instability or even failure. With inclined bedrock nearby, the mechanical behavior of passive loaded piles will be more complex. In order to study the mechanical behavior of passive loaded piles under such condition, laboratory model test was carried out, during repeatedly loading/unloading cycles. Axial force, side friction, bending moment, and lateral soil pressure were analyzed. The study is based on model test, and more related studies are needed before being applied to practical conditions. The results show as follows: Axial force distribution of the piles changes with the increase of load and becomes stable under high load. This phenomenon is related to the expansion of potential slip surface in piled foundation. The passive loaded pile that is close to load boundary has only one neutral point which is located in the lower part of the pile, and its side friction has a relatively stable direction. On the contrary, the direction of side friction of the pile that is far from load boundary changes frequently. Bending moment curves of passive loaded piles vary with the change of the distance between the piles and load boundary, and they intersect at the lower part of the pile. Bending moment is basically negative above the intersection and gradually turns into positive below it. The maximum lateral soil pressure of passive loaded pile is triple that of the adjacent soil, indicating that passive loaded pile can effectively limit the horizontal deformation of piled foundation. But when the pile is too far from load boundary, it will lose the ability to limit the horizontal deformation of piled foundation.