Abstract: In recent years, accidents that affect the existing rail transit structure or train safety have occurred frequently in the surrounding operations of urban rail transit. However, municipal engineering such as waterways inevitably intersects rail transit structures. How to implement effective technical measures to minimize the impact of construction on existing rail transit structures has become a research focus. The case history of the newly opened river channel above a shield tunnel of a rail transit line in Suzhou’s soft soil area is presented. This paper introduces a safety plan in the construction, the deformation control standards of the existing rail transit structures. The construction conditions are numerically simulated by establishing a three-dimensional numerical model. The measures of zoned displacement excavation, zoned excavation of soils in the river channel, load compensation for the excavation above the tunnel, and underwater excavation were taken for the riverbank revetment. Simulations were conducted by using MADIS (finite element analysis software), and the analysis results showed that adopting the above measures can minimize the impact of soil unloading on the rail transit. The deformation value of rail transit is less than the control standard value, The above technical solutions can provide reference for the design and construction of river engineering above shield tunnels in similar rail transit.

Key words: Soft Soil, River Excavation, Zoned Construction, Shielded Tunnel, Numerical Simulation