Abstract
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.
Highlights
With the rapid development of urban infrastructure construction and the constant improvement of the rail transit network, different forms of new construction, e.g., soil piling, excavation, and crossing, have begun to appear in the vicinity of the subway, which has a certain impact on the tunnel structure in operation
With the stagger-jointed assembled shield tunnel crossing the marine sedimentary silt layer with a burial depth of 10 m as the research object, the structural disease caused by soil mounds was investigated through on-site monitoring
With a shield tunnel crossing a marine sedimentary silt layer with a burial depth of 10 m as the research object, based on on-site monitoring, detection, and numerical simulation, the processes of structural deformation and damage under the soil mounds on the ground surface were explored, and data of structural deformation, cracking, opening of joints, and bolt axial force under different mound heights were obtained, which revealed the structural damage mechanism under the influence of the mound and presented the standard of controlling soil piling on the ground surface
Summary
With the rapid development of urban infrastructure construction and the constant improvement of the rail transit network, different forms of new construction, e.g., soil piling, excavation, and crossing, have begun to appear in the vicinity of the subway, which has a certain impact on the tunnel structure in operation. Rough model tests, Wu and Du [5] explored the relationship between tunnel deformation, burial depth, and mound position. Extensive soil piling on the ground surface occurred above the tunnel during its operation period, which resulted in structural diseases, such as segment cracking, water leakage, faulting of slab ends, opening of joints, and separation of the track bed, posing great threats to the operational safety of the subway. With the stagger-jointed assembled shield tunnel crossing the marine sedimentary silt layer with a burial depth of 10 m as the research object, the structural disease caused by soil mounds was investigated through on-site monitoring. With the additional load on the ground surface as the index, a standard for controlling the mound was proposed, which is of certain reference value for the control of soil mounds above subway tunnels in similar geological conditions
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