The article intrduces that in the construction of the 5th section of Chengdu third circle road(bit A),the exisited underground pipes cross over the trench,to secure the pipes,a method of narrow excavation were adopted,and to support the slope of the trench,anchor gunited supporting were adopted.

Through experiments in laboratory and theoretical analysis, variation of amount of carrying mud and sand by water flow and environmental influence of scouring and silting of mud and sand caused by excavating foundation trench of the immersed tunnel in the Yangtze River are studied.

During the construction of aeolian sand formation in the roadway,the improper excavation method in open channel section of inclined shaft will lead to loosening and falling of the sand,and consequently threatening the safety of construction workers and will increase engineering volumes of open channel excavation.