behavior of geogrid reinforced and unreinforced non-connected pile raft foundation

Presence of reinforcement elements such as geogrid in the cushion layer of the non-connected pile raft foundation changes the load transition mechanism and the portion of piles and raft from the total load. in this paper, experimental studies have been conducted on a non-connected pile raft foundation located in a sandy soil. the effect of parameters such as piles spacing, the thickness of cushion, position, length and number of geogrid layers on the behavior of load settlement, the portion of piles and raft from the total load, and distribution of axial and frictional stress along the pile and position of neutral axis were studied. the results showed that in unreinforced cases, with an optimum cushion thickness and piles spacing, the lowest settlement is observed. the use of geogrid in the cushion layer increases the bearing capacity and the portion of the piles from the total load and led to a move up in the neutral axis to the top of the piles. the optimum position and length of the first and second geogrid layers have also been studied.