Reinforcement of surrounding rocks of tunnel in landslide area with grouting technology

The double railway lines are being constructed in centro-west China. Because of the geography condition, many tunnels have to go through landslide areas. If the new tunnel is put in the landslide area, collapse and cave-in will take place during tunneling. More serious outcomes are that the interval between the existing tunnel and new one is very small, so that it is very easy to cause the existing tunnel in soft rocks to deform and fail. This case occurs several times in the centro-west railroad of China. Case study of grouting for the surrounding rocks of tunnel in the landslide area is made, including design, implementation and back-check of grouting effect. The reason of deformation of existing tunnel is analyzed with numerical method, and the grouting method under the special condition is discussed.