Abstract: The mud gushing and large deformation occurred to Laohongpo tunnel of DaliRuili railway when crossing contact zone between soluble rock and nonsoluble rock. According, the deformation, cracking and geological causes are analyzed, the mud gushing scope in main tunnel is explored by using bypass heading, the working chamber in tunnel is enlarged, treatment method of advanced horizontal grouting + highpressure horizontal jet grouting pile and advanced horizontal large pipe roof is adopted, and the support and lining structure are adjusted and strengthened. According to the site working conditions, the threebench method is adopted to separate and replace the steel frame in sections. The temporary invert or temporary cross brace is added at the arch foot of the steel frame to control the convergence deformation. The grid steel frame formwork lining is constructed in time, and the permanent secondary lining is constructed after the deformation becomes stable. The technology mentioned has been successfully applied to the construction practice in Laohongpo tunnel of DaliRuili railway, and good results have been achieved.

Key words:  , railway tunnel, large deformation of contact zone with mud gushing, bypass heading, horizontal jet grouting pile, advanced horizontal long pipe roof