Research On Evaluation And Engineering Control Of Large-scale Landslide Disasters Affecting The Safety Of Highway Bridges

With the rapid economic and social development of our country and the vigorous implementation of the western development strategy,restricted by many conditions such as topography,some highways and bridges under construction will inevitably pass through areas with poor geological conditions,and once they encounter large-scale landslides,mudslides,etc.Geological disasters will have a serious impact on the construction and operation of highways.This thesis is based on the national key research and development project "Research on the instability mechanism of typical geological disasters in the red bed area and new prevention methods and technologies",and carried out related research with the "Landslide treatment of a Bainigou bridge in Yunnan" as an engineering example.Through the preliminary site survey and geological survey,combined with the macroscopic deformation characteristics of the landslide area,the parameter inversion method is used to obtain the mechanical parameter cohesion and internal friction angle values,and the transfer coefficient method is used to analyze the landslide in natural conditions,rainstorm conditions and Under earthquake conditions,a true threedimensional model of the landslide area is established based on the preliminary survey results,and the disaster-causing process of the landslide under different conditions is simulated and analyzed.The safety analysis and evaluation of the force and deformation of the bridge piers affected by landslide deformation and damage are carried out.On this basis,the study of engineering control measures for landslide treatment will provide ideas and research methods for the treatment of similar projects in the future.This article mainly made the following progress through research:(1)Through on-site investigations and visits and geological surveys,combined with the macroscopic deformation characteristics of the landslide,it is judged that the landslide is in the early creeping deformation stage.The engineering geological sections 2-2? and3-3? with the main sliding directions of the landslide are selected as the calculation sections.The parameters of the sliding belt cohesion and internal friction angle obtained by the simulation method are 16.8k Pa and 17.4°,respectively.Among them,the c value of the parameter inversion analysis is 4% lower than the recommended value for the geological survey of sections 2-2? and 3-3?;The value of ? is 12.6% larger than the recommended value for geological survey of Section 2-2?,and 1.8% larger than the recommended value of geological survey for Section 3-3?,which is generally close to the value of geological survey data.(2)Select 4 engineering geological sections that are close to the main sliding direction of the landslide,and use the transfer coefficient method in the limit equilibrium method to calculate the safety factors and remaining sliding forces of the 4 sections under natural conditions,rainstorm conditions and seismic conditions,combined Standardize the stability analysis and evaluation of the slope.(3)Using the pre-processing rhinoceros software to establish a true three-dimensional numerical model of the landslide body to restore the true landform of the landslide area.Use FLAC3 D software to simulate the disaster-causing process of the slope under natural conditions,rainstorm conditions and seismic conditions according to the actual conditions of the landslide area,and obtain the safety factor map,displacement cloud map,plastic zone map and stress of the slope.Strain diagrams,etc.,analyze the stability of the slope under different working conditions and the factors that induce the sliding deformation of the landslide.Based on the above analysis,the pile element is imported into FLAC3 D software,and the shear value,bending moment value and deformation displacement of the bridge pier under different working conditions are simulated,and the safety of the bridge pier affected by the landslide deformation is analyzed and evaluated.(4)Based on the above theoretical calculations and numerical simulation analysis results,combined with the current situation of landslide deformation and the specific conditions of the project,a comprehensive treatment measure based on "single-row anchored anti-slide piles + cut square load reduction" is proposed,and FLAC3 D software is used to control the project.Numerical simulation of treatment measures.The analysis shows that the upper part of the landslide body has a certain restraining effect on its deformation development,but it cannot fully meet the protection requirements.By further setting up a single row of anchored anti-slide piles for numerical simulation analysis,the results show that it can not only improve the stability of the slope,but also greatly weaken the influence of the slope deformation on the pier.The deformation and displacement of the pier are within the safety limit,and the slope The treatment was in line with expectations and achieved good results,providing reference and basis for the follow-up treatment of similar projects.