Review on the response of unconnected piled raft foundation in clayey soil under earthquakes

The main purpose of this study is to review, assess, and compare the available researches conducted on the behavior of Unconnected Piled Raft Foundations in clayey soil under earthquake conditions. Soil-structure interaction causes bending moments in piles during earthquakes. Cushioned-PR with an interposer layer and connection form reduces inertial loading on the foundation during strong earthquakes. Pile head restraint is weaker in Cushioned-PR than Connected-PR, shifting peak bending moment from top to upper middle of piles. Horizontal constraint of Cushioned-PR is smaller, leading to higher horizontal displacement (2–10 times) during earthquakes. The results showed Unconnected Piled Raft (UCPR)reduces settlement by 47% compared to conventional pile groups (Pg). Increasing pile length reduces settlements. Cushioned-PR lowers superstructure acceleration and bending moment, with 28%–54% less bending moment than Connected-PR. Cushion thickness reduces pile load and redistributes force, affected by geogrid layer. Geogrid increases raft axial stress, optimal at (u = 0.0 and 0.3) m from pile head, raising raft stress ratio and reducing pile load-sharing ratio.