Analysis And Control Measures Of Landslide-tunnel Interaction

In recent years,China's railways and highways have extended to mountainous areas in west China,which is inevitable to pass through defective geological bodies,such as landslides in various ways.Unfavorable geological bodies are extremely harmful to railways and highways and also lead to a significant impact on them.Besides,the coupling mechanism between the tunnel and the undesirable geological bodies is complex,causing numerous engineering problems.Based on the prominent problems encountered in recent years when tunnels pass through landslide bodies,in this paper,field investigation,theoretical analysis,numerical simulation,on-site monitoring and engineering verification are carried out to study the failure mode,action mechanism and control technology of tunnels under landslide-tunnel coupling interaction.The main work and research results are as follows:(1)The failure mode of the tunnel under the landslide-tunnel coupling effectFocusing on the development process and failure characteristics of the landslide,combined with the location of the tunnel passing through the landslide body,six representative tunnel failure modes under the landslide-tunnel coupling effect are proposed,namely longitudinal tensile failure in traction section,longitudinal shear failure in sliding surface,lateral shear failure in sliding surface,lateral dislocation failure in landslide boundary,longitudinal crushing failure in thin sliding body and dragging failure in lower sliding body.The analysis of typical cases demonstrates the features of various failure modes.(2)Landslide-tunnel coupling mechanismRegarding the three failure modes: lateral dislocation failure in landslide boundary,lateral shear failure in sliding surface,and longitudinal shear failure in traction section,a railway tunnel in northwest China,Dayuan 1 of Guangle Expressway and a highway tunnel in southwest China were selected for study.On the basis of the deformation and failure characteristics of the landslide and the tunnel,the tunnel-landslide coupling model was established,and its coupling mechanism was presented from the time and spatial distribution.According to the research,the landslide deformation can directly cause the deformation and destruction of the tunnel when the tunnel passes through the landslide body.The excavation of the tunnel may cause or aggravate the deformation development of the landslide.Under different modes of landslide action,the tunnel lining structure exhibits different deformation and failure characteristics,including stretching,shearing and squeezing.The deformation and failure features of the tunnel are consistent with those of the landslide in terms of time and space distribution.(3)Control technology of landslide-tunnel coupling effectBased on the failure mode and mechanism of landslide tunnel interaction,the control principle and technology of tunnel deformation on the basis of stable landslide are proposed.In order to limit the local deformation and stress,avoid the tunnel bearing and transferring the landslide thrust,and at the same time achieve the purpose of restraining groundwater,on the basis of stabilizing the landslide,the steel tube control grouting technology is used to reinforce the influence range of the landslide tunnel coupling action.Through practical engineering application,the reinforcement effect is demonstrated and the practical engineering problems are solved.