Abstract:

The largespan section on the west shore of the north tube of Xiangjiang River Crossing Tunnel on Yingpan Road in Changsha City is a shallowburied, largespan underwater tunnel section under complex conditions. The construction design is determined by means of engineering analogy. 3D numerical assessment and test in the field are carried out before construction so as to assess the safety of the ground reinforcing technology, the construction methods and the lining parameters of the underwater lagerspan section. Conclusions drawn are as follows: the excavation safety can be guaranteed for the sake of the assistant measures, the lining parameters and the construction methods adopted; the pillar of the smallspaced section between the left drift and the right drift and the connection positions of the largespan section are critical parts that have impact on the tunneling safety and should be strengthened.

Key words: Xiangjiang River Crossing Tunnel, shallow overburden, large span, construction control, safety assessment