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

Abstract

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.