Squeezed branch piles, originally developed for building and bridge foundations, have been downsized and deployed at larger pile spacing for reinforcing embankments over soft soils. However, the working mechanism of squeezed branch pile-supported embankments remains unclear. In this study, a three-dimensional numerical model of this embankment was established based on field tests. The analyses consider different pile types (squeezed branch piles and straight piles) and pile-head structures (beam-type cap and plate-type cap). These concrete components were modeled utilizing an advanced concrete model, which captures the strain-softening/hardening and yielding behavior. Simulation results show that squeezed branch piles provide better settlement control in the subsoil beneath the embankment than straight piles for the studied cases. The beam-type cap with squeezed branch piles behaves as a pile-beam foundation that reduces maximum settlement by around 38% compared to that of the plate-type cap, while the plate-type cap system functions as a composite foundation that enhances surcharge capacity by about 35–40%. The instability of the embankment is driven by tensile failure in concrete: The beam-type cap leads to a localized failure along the ground beam, and the plate-type cap system induces a progressive failure centered on the squeezed branch piles. Within the plate-type cap, the dimensions of the pile-head plate significantly influence settlement control and the stability of the embankment in soft soil.

Concrete-core cement mixing (CCM) piles are an effective ground improvement technique for soft soils, enhancing bearing capacity and material efficiency by introducing a stiff core. However, the mechanisms governing vertical bearing behavior, ground failure evolution, and the influence of key structural parameters remain insufficiently understood. A series of numerical models of CCM piles with varying core lengths and irregular cross-sectional configurations are established using a four-dimensional lattice spring model (4D-LSM). The load transfer mechanisms, the mobilization of shaft resistance, and settlement responses under vertical loadings are systematically investigated. The predicted load–settlement curves and failure patterns exhibit good agreement with laboratory model tests, demonstrating the accuracy and applicability of 4D-LSM. Parametric analyses indicate that core length is a dominant factor influencing bearing performance, with the most significant improvement achieved when the core length is 0.8–1.0 times the pile length. Bamboo-shaped piles significantly enhance shaft resistance by enlarging the pile–soil contact area, resulting in ∼40% increase in ultimate bearing capacity and reduced settlement compared with uniform-diameter piles. Properly designed stepped piles can maintain bearing capacity while reducing material consumption. Optimizing the core length and cross-sectional configuration can effectively enhance bearing performance while improving material efficiency, highlighting the sustainability potential of CCM piles in soft ground engineering.