Lateral response of monopile reinforced by cement-improved soil in clay to monotonic and cyclic loadings: Laboratory model test and theoretical investigation

A systematic study was performed in laboratory model tests to assess the response of cement -improved reinforced monopiles to lateral monotonic and cyclic loading in clay. The overall load-deflection behavior and profile of the bending moment was fully studied in monotonic tests, in addition to the p -y curves of the reinforced and unreinforced piles. Cyclic loading tests were carried out at different cyclic magnitude values and load ratios, and the cement-improved soil reinforcement range was also varied. This study provides several insights into the ongoing development of the deflection, unloading stiffness and bending moment of cement-improved soil reinforced piles as cycling progresses, which can provide empirical design recommendations for cement-improved soil reinforced monopiles subjected to lateral cyclic loading. Based on the typical p -y curve models of pile in soft clay and stiff clay, by considering the proportion of soil resistance shared by cement-improved soil and soft clay around a pile under lateral load, the modification factors of two parameters pu and y50 are derived, and then a modified p -y curve model of cement-improved soil reinforced piles in soft clay is established.