Study on Bearing Characteristics and Load Transfer Behavior of a Slurry-Modified Stiffened Deep Cement Mixing Pile considering Core Pile Types

The stiffened deep cement mixing (SDCM) pile, a composite structure comprising a reinforced core pile and cemented soil, has gained extensive application in geotechnical engineering due to its superior bearing capacity and simplified construction procedures. Although the construction of SDCM piles is more environmentally friendly and greener than that of bored piles, the generation of substantial waste slurry during construction processes remains a significant ecological concern. Therefore, this study utilizes the slurry discharged during construction to configure cemented soil to recycle the waste slurry and reduce the slurry pollution. A field static load test with core pile being a pipe pile was conducted to investigate the bearing performance and load transfer mechanism of the slurry-modified SDCM pile. Based on the test, a two-dimensional coupled discrete-element and finite-difference (DEM-FDM) model was developed considering three different core pile types (pipe pile, square pile, and nodular pile). By setting monitoring points in the DEM-FDM model, the relative displacement variation patterns of core pile–cemented soil interface with depth were obtained for different core pile types, and a principle of relative displacement superposition to explain these findings was proposed. Additionally, interface shear simulations under different vertical stresses were carried out, and the constitutive model of core pile–cemented soil interface skin friction–relative displacement was obtained to provide assistance for the bearing capacity calculation and design of SDCM piles.