Abstract:

The underdrain of ancient canal beneath Shi-Tai Expressway is a large-scale graff cross structure of main channel in middle route project of South-to-North water diversion. This underdrain is three-arch culvert structure, where construction condition is very complex. The soil of underdrain constructed using partial excavation method are fine sand and medium-fine sand mostly, and passing vehicle load on expressway is heavy; so the construction is the most difficult one and the excavation width (25.6 m) is the widest for similar domestic engineering. The construction process according to actual construction sequence and craft is simulated by using FLAC3D software. The stratum deformation, the stress and the distribution of plastic region are discussed in detail. The calculation result indicates that the underdrain construction scheme of underpass is reasonable; and it has guidance function on the underdrain construction scheme of underpass; and it also provides basis for the range of stratum reinforcement. The practice of construction process verifies that the assistant reinforcement measures are effective for the safety of railway lines and tunnels based on the results of numerical simulation.

Key words: three-dimensional numerical simulation, South-to-North water diversion, arch culvert, undercrossing expressway