Experimental analysis and mechanical model of interaction between warm frozen silt and pre-bored grouted planted nodular pile

To reveal interaction mechanism on the interface between the pre-bored grouted planted nodular pile (PGPN) and warm frozen ground, and to compare its bearing performance with that of cast-in-place pile, shear tests on the interface of the two types of pile were carried out at negative temperature under different influencing factors through self-designed test devices. Combined with the single factor method and response surface method, the influence laws of various factors and interaction on the adfreezing force of the interface were analyzed. The micro-deformation mechanism of the interface could be revealed by the binary medium model, and volume breakage rate and Weibull distribution function were introduced to establish the constitutive equation of the interface. The results showed that the cemented soil slurry could strengthen the frozen soil around the pile, The shear zone of the interface appeared on the frozen ground around the pile rich in ice film, and the shear stress -displacement curve showed a strain softening type and included four stages. Among all the influencing factors, temperature has the most significant effect on adfreezing force. The freezing strength has an exponential rela-tionship with temperature, and the water content and normal stress have a linear relationship with freezing strength. Compared with the traditional cast-in-place pile, PGPN pile has higher bearing capacity and more stable deformation. The proposed interface constitutive model scientifically reveals the microscopic deformation mechanism of the shear zone. The model data fit well with the test results, which could provide valuable reference for the design and calculation of the bearing capacity of the pile foundation in warm frozen ground.