| Due to the special topographical and geological conditions in Southwest China,the stability of high and steep slopes is outstanding,which has become one of the key technical problems restricting the development of resources and engineering construction.At present,the study of landslide hazard risk assessment,geological hazard risk assessment and risk management,and the prevention and control of traffic landslide and high slope diseases in mountainous areas are the key and difficult points.Based on the study of construction technology and seismic dynamic response of highway tunnel passing through ancient landslide group,the main technical characteristics and key technical problems of slope engineering are summarized and analyzed.From the aspects of geological conditions,design theory and method,implementation process control and so on,some new understandings are put forward,and the theory of slope engineering investigation,design and control is studied.In view of the research situation of mountain slope at home and abroad,the stability analysis methods of ancient landslide slope are listed.Based on the unsaturated seepage theory,the finite element strength reduction method and the seismic response analysis method,combined with the study of the failure type and prevention method of the steep slope of the ancient landslide,the comprehensive treatment engineering idea of the ancient landslide and the construction control analysis of the tunnel crossing the ancient landslide are carried out.Through the study of 3D pile arrangement simulation method of 2D plane strain problem,the simulation principle of 3D pile arrangement unit of 2D plane strain problem,the simulation of pile structure,the assumed conditions of 3D pile arrangement unit,the parameters of 3D pile arrangement unit,the 3D pile soil interaction,and the bearing capacity analysis method of 3D pile arrangement are obtained,and the stability analysis of treatment condition of tunnel crossing ancient landslide is carried out.The excavation and support of ancient landslide tunnel and the general maximum displacement of groundwater level of steep slope of ancient landslide occur in the scope centered on the highway scarp.The original design of multi-level anti slide piles effectively blocks the revival of the lower slope of ancient landslide.The revival signs of ancient landslide are located in the cracks of several scarps from the top to the bottom of anti slide piles.Multiple groups of sliding surfaces constitute the revival of multiple ancient landslides,and the slope is still located Creep slip state.Among them,the excavation and support of the tunnel have obvious disturbance to the surrounding rock of the ancient landslide,and there are signs of the revival of the ancient landslide.Generally,the maximum displacement of groundwater level of ancient landslide treatment,tunnel excavation and support,and ancient landslide steep slope occurs above the highway scarp.The original design of multi-level anti slide pile+multi-level anti slide pile(anchor cable)treatment effectively blocks the revival of the lower slope of the ancient landslide.The signs of the revival of the ancient slide slope are located in the cracks and cracks of the anti slide pile(anchor cable)scarp,and multiple sets of sliding surfaces constitute multiple ancient slides Slope,the lower part of the ancient landslide has been effectively controlled,the upper part has small deformation signs of resurrection,and the slope is still in the state of peristaltic sliding.Among them,the excavation and support of the tunnel have obvious disturbance to the surrounding rock of the ancient landslide.In general,the maximum displacement of groundwater level in excavation and support of ancient landslide tunnel and steep slope occurs in the range with highway scarp as the center.The distribution of tunnel lining displacement has a sudden change,the distribution of lining axial force is relatively uniform,the distribution of lining shear force and the distribution of lining bending moment has a sudden change,which is related to the compression and uplift of the right wall of tunnel lining by the upper ancient landslide.With the treatment of tunnel reinforcement measures The implementation can not meet the overall safety requirements of the tunnel,so it is necessary to study the ancient landslide treatment,bridge and tunnel construction scheme analysis.Generally,the maximum displacement of groundwater level of ancient landslide treatment,tunnel excavation and support,and steep slope occurs above the highway scarp.The distribution of tunnel lining displacement has a sudden change,the distribution of lining axial force is relatively uniform,and the distribution of lining shear force and lining bending moment has a sudden change.With the implementation of tunnel reinforcement measures,it can meet the overall safety requirements of the tunnel,which needs to be further improved The deformation of bridge and tunnel is monitored and analyzed.The analysis of the seismic dynamic response of the steep slope treatment of the tunnel crossing the ancient landslide shows that the seismic dynamic response will induce the creep slip of the ancient landslide,and the multi-level anti slide piles cut off the sliding surface,which has the effect of preventing the whole landslide of the ancient landslide.The shear strain rotation,axial force,shear force and bending moment of the left and right side of the tunnel lining change dramatically,which may lead to deformation and fracture of the lining.A large number of engineering practice shows that the stability analysis of ancient landslide and the design of protection and reinforcement engineering should be based on its deformation mechanism and failure mode.According to different deformation mechanism and potential failure mode,corresponding protection and reinforcement engineering countermeasures should be designed.Therefore,it has important theoretical significance and reference value to study the deformation failure mechanism and stability analysis of ancient landslide steep slope. |
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