Abstract: Toothed piles with sand liner are composite loaded piles which are formed by combining sand liner and pre-stressed pipe pile. Based on the spherical cavity expansion theory, this paper analyzes the impact of cavity expansion on the soil around and beneath the pile. The results indicate the mechanism of axial load capacity of toothed piles with sand liner. The results show that the side friction force consists of two parts, i.e. the friction force between soil and pile, and shear force of remolded soil between pile and teeth. We made a correction to the coefficient of soil disturbance in the equation to consider the effect of soil disturbance during the piling process. The paper also analyzed the proportion of toothed pile shear force in the total pile bearing capacity. The calculation results and its theoretical equation are proved to be correct and reliable based on verification with national regulation, provincial standard, theoretical derivation formula computing result and the static load test on site. This research methodology provides the theoretical basis for future application and improvement of toothed pile in future production. The research conclusion also has practical significance.

Key words: toothed pile, shear stress between the tooth, correction coefficient of remolded soil, cavity expansion impact, spherical cavity expansion theory