English：

Combined with the key technology of design and construction of the flexible steel shed tunnelat the port of Nanbeiya Tunnel in Baoji-Tianshui section of Lanzhou-Lianyungang Railway, this paperexpounds the comparison and selection of the schemes for the treatment of railway slope diseases undercomplex environment, this paper puts forward a new way and method suitable for complex environment,and introduces the applicable conditions, structure design and construction technology of flexible steelshed tunnel, with emphasis on the composition, material and function of unique structure, specialconstruction technology for lower structure and upper structure of steel shed tunnel. There is a risk ofrockfall at the exit of the railway tunnel, but the complex environment makes it impossible to build opencut tunnel, providing scientifically feasible protection schemes and key construction technology, it isworth popularizing and applying to the diseases treatment of similar railway and highway tunnel port.