Abstract: To study the influence factors of sub peak adfreezing strength at the interface between frozen soil and structure, the typical fine sand located in the Hexi area of Nanjing subway construction site was selected as test sample. The large-scale multi-functional frozen soil-structure interface shearing instrument was optimized and improved to conduct direct shear tests of adfreezing strength considering multi-influencing factors. Based on the specific definition and the agreement of quantitative criteria for sub peak adfreezing strength, it was found that the shear stress was typical of steepness after the limit peak, and the peak post shear stress changed periodically . The relationships among sub peak adfreezing strength, interface temperature, roughness and normal stress were fitted and found to be inverse proportional linearity, quadratic polynomial, proportional linear relationship respectively. Through the database management software, it was found that the normal stress and roughness were the key influencing factors, but the interface temperature was non-critical influencing factors. The three-element sub peak adfreezing strength prediction model coupled with interface temperature, normal stress and roughness was constructed by multivariate nonlinear regression. It can provide important adfreezing strength parameters for artificial freezing reinforcement design, shield construction and underground structure design in artificial freezing reinforcement area or permafrost area.

Key words: sub peak adfreezing strength, influential factors, influence rule, prediction model, frozen soil, interface