Abstract: The theoretical calculation, field monitoring, and numerical simulation analysis are employed to examine the load characteristics of the surrounding rock and segments of a super-large diameter shield tunnel on Chunfeng road. Typical sections of the Chunfeng road tunnel are selected to conduct a comparative analysis of the theoretical calculation values of full-soil cover and the measured pressure data of surrounding rock. The mechanical behavior characteristics of the segment structure, steel bars, and bolts are obtained through field monitoring, and a three-dimensional numerical model of the segment including actual reinforcement is established for comparison and verification with the measured values. The following conclusions are obtained: (1) The surrounding rock pressure measured by the earth pressure gauge in the sandstone formation is in good agreement with the calculated value of the full-soil cover theory without considering the water pressure. (2) The measured load on the off-load side of a section increases by 50% relative to the calculated value, and the calculation of surrounding rock load should consider the off-load effect of additional load for local amplification. (3) The monitoring data analysis shows that the mechanical safety redundancy of the segments and rebar is relatively high, which does not exceed 40% of the design strength value. (4) The structural stress values obtained by modeling are in good agreement with the measured values. (5) Without considering the difference of artificial installation, the axial force distribution of bolts between blocks is relatively uniform.

Key words: super-large diameter shield tunnel, surrounding rock load, mechanical behavior, field monitoring