Field test and numerical simulation of vertical bearing characteristics of stiffened deep cement mixing pile

The stiffened deep cement mixing (SDCM) pile is widely used in geotechnical engineering because of its high bearing capacity, high skin friction and low settlement. In this paper, the bearing characteristics of the SDCM pile are investigated through field tests and a series of numerical simulations. The results show that the load-displacement curve of the SDCM pile is slow-varying. After the test is completed and the entire cross-section of the pile is excavated, the core pile is tightly bonded to the cemented soil without any damage, indicating that the core pile and cemented soil can work together effectively; the reduction of the core pile length L_C prevents the load at the pile top from being effectively transferred to the cemented soil below the core pile bottom, which results in the insufficient play of the load-bearing performance of the SDCM pile; the increase of the core pile content ratio ω can effectively improve the bearing capacity of the SDCM pile, but when the core pile content ratio ω is more than 0.4, the rate of increase in bearing capacity slows down. The results of this research can provide a reference for in the calculation of bearing capacity and design of the SDCM pile. Finally, a new correction factor λ for the skin friction is proposed to consider the effect of the core pile content ratio separately, so as to correct the calculation method of the specification JGJ/T 327—2014.