Structural Damage of Subway Tunnel Buried Shallowly in Silt Layer under Soil Mound Loading

Based on the structural damage of the shield tunnel caused by a soil mound on the ground surface in a section of subway in Tianjin, China, the deformation and the cracking process of the segment under soil mound loading were simulated. The variations of segment, bolt, and rebar stresses with the height of the mound were analyzed. The results show that, for the stagger-jointed assembled shield tunnel that crosses the marine sedimentary silt with a burial depth of 10 m, as the mound loading increases, the damage is concentrated in the vault and hance. When the mound loading is 16.0 kPa, the segment is damaged; the crack depth and bolt axial force of the vault increase rapidly when the mound loading reaches 38.6 kPa. The analysis results are basically consistent with monitoring data. Based on the above analysis, the control standard of mound loading should be 38.6 kPa. The results of this study can provide data reference for control and structural protection of soil mound loading for similar subway tunnels.

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