Challenges,Countermeasures and Reflections on the Construction of Cross River Shield Tunnels
With the development of China's economy,the construction volume of cross river shield tunnels has increased.At the same time,the shield diameter,excavation distance,and tunnel burial depth of cross river tunnels are constantly increasing,and the construction difficulty is also increasing.This paper conducts an in-depth research on the key technical issues in the design and construction of ultra large diameter underwater shield tunnels.Develop corresponding countermeasures based on the main characteristics of the"long,large,high,and deep"cross river tunnel.A new evacuation mode and ventilation and smoke exhaust strategy have been proposed for the fire evacuation problem of ultra long tunnels.In terms of longitudinal deformation control of ultra large diameter shield tunneling,dual liquid synchronous grouting technology is used to control the floating of the tunnel.In the face of waterproofing difficulties in high water pressure environments,the layout of dual sealing gaskets has been optimized.Faced with the problem of deformation of tunnel structures caused by soil erosion or sedimentation,a new type of DDCI connection structure is proposed to improve the bearing capacity of large-diameter shield tunnel structures.At the same time,discussions were conducted on new technologies and materials for auxiliary projects such as prefabricated internal structures and green environmental protection tunnel pavement,and in-depth consideration was given to the development of large-diameter cross river shield tunneling in the future.
ultra large diameterextra long distanceunderwater tunnelshield method