Environmental geological problems and technological countermeasure for Shanghai tunnel-bridge engineering across Changjiang River

Shanghai tunnel-bridge engineering across Changjiang River is a national important basic construction project in estuarine of Changjiang River.It adopts tunnel with bridge and double layers for expressway in upside and rail in underside.It is supreme tunnel-bridge engineering in the world at present.On a field basis of hydrologic and geological condition along the construction line,this paper expatiated on the environmental geological problems as soft soil deformation,water and soil piping,movement of sand under water,danger of shallow natural gas, beach erosion and deposition,sand liquefaction and land subsidence,analyzed on the potential harm for engineering,evaluated the geological safety for this project,and advanced corresponding prevention countermeasure and technological measure.The geological condition is much safer in land section of engineering,common safe in bridge section and less safe in tunnel section.It can effectively avoid and reduce danger of works induced or aggravated by geological hazard using mature construction craft and methodology.