Abstract: V-shaped super-large diameter shield tunnel has been commonly adopted in cross-river projects. It is necessary to study the influence of longitudinal slope on segment floating during tunnel construction. Based on the west extension project of Jihua road in Foshan city, a numerical analysis model of shield tunneling in silty sand strata considering time-varying characteristics of grout is established. The influence of tunnel longitudinal slope on segments floating is studied. The deflection moment is applied by changing the load distribution of propulsion system, and the relationship between deflection moment and segments floating under different slopes and burial depth is analyzed. The results show that: (1) The floating of segments increases with the number of driving rings, and then tends to be stable. (2) For shallow buried tunneling, the floating of segments is the largest in the downslope section, larger in the horizontal section，and the smallest in the upslope section； for deep buried tunneling, the slope has little effect on segment floating. (3) For all longitudinal slopes, the positive deflection moment can inhibit the floating of segment, and the inhibition effect is better for deep buried tunneling.

Key words: shield tunnel, silty sand stratum, longitudinal slope, floating of segments, number of driving rings, deflection moment