Study on the floating mechanism of bottom segments in metro shield construction projects
To investigate the buoyancy phenomenon affecting bottom segments during shield tunneling construction projects,this article conducts a phased theoretical analysis across four stages of shield construction:segment assembly,jacking with hydraulic jacks,simultaneous grouting,and grout consolidation.The theoretical analysis indicates that the bottom segment's floating phenomenon can be categorized as localized floating.Mechanical analysis is carried out against the bottom segment during the simultaneous grouting phase,focusing on the interplay between dynamic floating force,inter-ring resistance,viscous resistance,and gravity.By using a separation of variables method,a formula for calculating the buoyancy of bottom segments is derived.The calculation formula is validated for scientific accuracy by applying it to the measured construction data from a section of Shenzhen metro line 13 to calculate the buoyancy of the bottom segments.The research reveals that the floating of bottom segments progresses through the following stages:sudden increase,slow increase,and gradual stabilization.Through controlled variable analysis,the impact of grouting pressure and the water-cement ratio of grouting materials on buoyancy is examined.Based on the results of the analysis,scientifically effective measures for controlling buoyancy are proposed.The research outcomes can serve as a technical foundation for the design and secure construction of buoyancy-resistant shield tunnel segments.
NETL
NSTL
万方数据
维普
