Abstract: In order to explore the floating law of large diameter shield segments in high water pressure silty clay stratum and its correlation with construction parameters, the effects of different grout proportions and key construction parameters on the floating of segments were studied through the laboratory grout ratio test and grout performance test, combined with the field test of Jinan Yellow River Tunnel project. The results show that increasing the dosage of cement, fly ash and water-reducing agent can shorten the setting time of the grout, which is conducive to the decrease of segment floating, and the
decrease of bleeding rate, fluidity and consistency, which is unfavorable to the control of segment
floating. The floating law of large diameter shield tunnel segments is approximately parabolic, and it
quickly rises within 10 hours after the start of grouting, then slows down rapidly, and becomes stable
after 25 h ~ 30 h. Due to the joint influence of the various factors, adjusting only the proportion of grout
may not be able to control the floating of the segment. It is recommended to simultaneously reduce the
difference between the volume of mud discharged and mud entering and the cutter head contact pressure,
maintain the cutter head torque, reduce the difference of the thrust pressure of the upper and lower
section jack and the difference of the synchronous grouting pressure, additionally, appropriately extend
the temporary downtime, driving and assembling time of the segment, and reduced tunneling speed to
further control of segment float.

Key words: tunnel engineering, large diameter, shield tunnel, segment floating, synchronous grouting, field test