Research On Characteristics Of Force And Deformation During Excavation And Support Of Dual Structure Slope

Aiming at the problems of complicated structural stress and deformation characteristics and easy instability damage during the excavation and support of dual-element slopes,this paper takes the soil-rock dual-element slope of the excavated section of mountain highway as the research object,and carries out pile-anchor reinforcement of the dual-element edge The slope stability evaluation and steady-state seepage analysis are designed to reveal the instability mechanism and anchor cable prestress loss characteristics during the excavation and support of the dual slope,and provide a basis for the excavation and support of the dual slope.The paper relies on the treatment project of the right side slope of the K5+220-K5+770 section of the TJ1 A section of the Jiangwen Expressway(hereinafter referred to as the Hetangba slope)to carry out the deep displacement monitoring of the slope and the field soil test;the finite element method is used to establish the slope excavation Supporting two-dimensional model,a new method of checking simulation parameters based on deep displacement monitoring data and P-value inspection is proposed;under the premise of checking simulation parameters,steady-state seepage is carried out for multiple supported slopes and supporting structures.Analysis of force and deformation characteristics.Propose and carry out the analysis of the excavation support process of the dual structure slope.Finally,the prediction model of prestress loss is optimized.The research results are as follows:(1)It is determined that the Hetangba slope belongs to the gravel soil-bedrock dual structure slope.The on-site topography,geomorphology and geological structure survey of the Hetang Dam dual structure slope was carried out to obtain the origin and distribution characteristics of the gravel soil on the Hetang Dam slope.Analyze the stability influencing factors and deformation failure mechanism of dual structure slopes.(2)Analyze the monitoring data of deep displacement and anchor cable prestress loss,and obtain the change characteristics of deep displacement and prestress loss before secondary slope support.Through on-site particle screening test and large shear test,the value ranges of c and ? of the on-site gravel soil are obtained.(3)Establish a two-dimensional model of simplified seepage slope for multiple constructions,and propose a simulation parameter verification method based on P value inspection.The application of anti-slide piles and prestressed anchor cables will gradually change the force and deformation characteristics of the slope and improve the safety factor of the slope.The method of verifying the simulation parameters based on the deep displacement monitoring data and P value inspection is verified.(4)Using the pore water pressure superposition calculation method,study the characteristics of the steady-state seepage effect on the slope and supporting structure deformation during the two supporting processes.The effects of steady-state seepage on the displacement,stress,strain,and safety factor of the slope during the completion of excavation,primary support and secondary support are obtained.The force and deformation characteristics of prestressed anchor cables and anti-slide piles before and after steady seepage are obtained.(5)Aiming at the problem that the most dangerous construction conditions are difficult to judge during the slope excavation and support process,based on the simulation parameter check and the superposition calculation of pore water pressure,the analysis of the slope excavation and support process is proposed,and the pores imposed on the slope of Hetang dam are analyzed.The slope stress and strain and the force and deformation characteristics of the supporting structure in 11 working conditions before and after water pressure.The most dangerous working condition of Hetangba slope excavation and support is the secondary slope excavation stage of the primary support.(6)Aiming at the problem that the loss of anchor cable prestress over time cannot be reflected in the finite element model,regression analysis and staged statistics are used to obtain an improved model of anchor cable prestress loss calculated in stages.Analyzing the applicability of the improved model,the improved model can control the prestress loss prediction error within 8.9%.