Numerical analysis of load-transfer mechanism of stiffened deep cement mixing pile foundation

To reveal the load-transfer mechanism of stiffened deep cement mixing (SDCM) piles, the three-dimensional numerical analysis of a pilot pile was first conducted using the finite element software Diana, which can simulate the Mohr-Coulomb friction interface. Comparisons show that the computed load-settlement curve and distribution law of the skin frictions agreed well with the measurements. Then, the numerical method was employed to model the group pile foundations with four SDCM piles. It shows that the bearing capacity increased with increasing pile spacing and core lengths. And most loading was shared by the stiffened cores. It indicates that negative skin frictions may arise at the bottom of a reinforced concrete pile cap or the end of a stiffened core. And there is a hysteresis effect for the peak frictions on the two interfaces to mobilize. Meanwhile, plastic shear zones in soil and DCM pile may sequentially arise with increasing load.