Abstract:

The construction difficulty and risk of cross passage of urban metros in waterrich sandy stratum is very high. Hence, a comparison is made among dewatering, freezing, jet grouting and grouting reinforcement in terms of technology and economy, and a combination consolidation scheme of grouting reinforcement + dewatering is selected to improve the stability of surrounding rocks and reduce influence of construction on surrounding environment. During the construction of cross passage, advanced pregrouting in tunnel and tube well dewatering on ground surface + light well point dewatering in well outside tunnel are adopted. During the construction of water pit, surrounding small duct grouting and in pit light well point dewatering are adopted. Meanwhile, the deformation of the tunnel and ground surface during construction is monitored; and the monitoring results show that the deformation of the tunnel and ground surface is quite small which indicates the safety and feasibility of the abovementioned technologies.

Key words: metro shield tunnel, cross passage, grouting reinforcement, dewatering, mining method