The inhibition effects of anti-floating anchors that are arranged on the shield tunnel on tunnel uplift are studied. A three-dimensional finite element model of foundation pit excavation above an existing shield tunnel with anti-floating anchors was established. With the consideration of the length, diameter, angle, spacing, and the number of each tube of the anti-floating anchor rods, the influence of different anti-floating anchor layout on its inhibition effect of shield tunnel uplift was analyzed. Meanwhile, considering the excavation condition of foundation pit and the relative position relation between foundation pit and shield tunnel, the effect of anti-floating anchor in different conditions was analyzed. The results show that: The anti-floating anchors arranged on the segments of the shield tunnel have a certain inhibitory effect on tunnel uplift. The inhibition effect of the anti-floating anchor will be better with the longer length, larger diameter, smaller spacing, and more number of each tube of the anti-floating anchor rods. It is sensible if the anti-floating anchor arrangement angle is around 30°. The greater the buried depth of the shield tunnel, the better the inhibition effect of the anti-floating anchor. The greater the length or width of the foundation pit excavation and the greater the excavation depth, the more obvious the effect of the anti-floating anchor.

Step tapered steel composite piles have excellent mechanical performance and they are widely used in engineering, but the related theoretical research is lagging behind. The calculation method of the vertical bearing capacity of the pile type was studied, and the load transfer rules were analyzed. The limit state of the pile foundation was analyzed. Considering the action of the steel tube and the bearing capacity at the stepped cross section, the vertical ultimate bearing capacity calculation formula of the super-long and large-diameter steel tube composite pile with stepped cross-section was derived by using the coordination relationship between the pile and soil displacement. The vertical bearing capacity of No. 37 pile foundation of Yushan Bridge was calculated by using this method and the calculation method in the current standard, which were compared with the measured value in the self-balancing test of the test pile. The results show that the self-balancing test curve of the test pile is smooth and without mutation. Besides, the bearing capacity of single pile is 120056 kN. Moreover, the deviation between the calculated value of the current standard formula and the measured value is too large, while the calculated value by using the method in this paper is close to the measured value, which verifies the reliability of the method in this paper.