Parametric Study on Analyzing the Effect of Soil–Cement Strength on the Uplifting Behavior of HSCM Piles Installed in Marine Soft Clay

The Helix-Stiffened Cement Mixing (HSCM) pile is a composite pile constructed by grouting the soil–cement during the installation of the helical pile. A series of 3-D Finite Element Method (FEM) models were developed to investigate the uplifting behavior of HSCM piles installed in marine soft clay. The uplifting behavior of HSCM piles was compared to the Stiffened Deep Cement Mixing (SDCM) piles and the difference was discussed. The FEM results showed that the uplifting ultimate bearing capacity of the HSCM piles and SDCM piles increased with the soil–cement-strength-to-clay-adhesion ratio (Cref/su) until the ratio reached 20 and 40, respectively. The failure mode influenced the uplifting behavior of HSCM piles. At Cref/su ∈ 40,80, the HSCM pile incurred damage at the pile–soil interface, which gradually shifted to the steel pipe and soil–cement interface as the Cref/su was further decreased. Based on the FEM results, the empirical formula for estimating the uplift ultimate bearing capacity of HSCM piles under different failure types was proposed, which provided reliable guidance for designing HSCM piles.